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"ASPECTS OF SOCIAL ORGANIZATION AND DIURNAL ACTIVITY PATTERNS OF CALIFORNIAN BIGHORN SHEEP (OVIS CANADENSIS CALIFORNIANA DOUGLAS 1829)  by  THOMAS ROSS ECCLES  B.Sc,  The U n i v e r s i t y o f B r i t i s h Columbia  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in  THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF ANIMAL SCIENCE  We a c c e p t t h i s t h e s i s as conforming t o the required standard  THE UNIVERSITY OF BRITISH COLUMBIA November 1981  \u00A9 Thomas Ross E c c l e s , 1981  \u000CIn p r e s e n t i n g requirements  this thesis  British  it  freely available  for  that  f u l f i l m e n t of the  f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y  of  agree  in partial  Columbia,  I agree  f o r reference  permission  scholarly  that  the L i b r a r y  shall  and s t u d y .  I  f o r extensive  p u r p o s e s may  for  that  shall  /)/y  /?i  of this  It is thesis  n o t be a l l o w e d w i t h o u t my  permission.  Department o f  *56JEAAIE_-  The U n i v e r s i t y o f B r i t i s h 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5  thesis  be g r a n t e d by t h e h e a d o f my  copying or p u b l i c a t i o n  f i n a n c i a l gain  further  copying of t h i s  d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . understood  make  Columbia  written  \u000CAbstract  The s o c i a l bighorn  organization and diurnal  ewes  were  investigated  activity  from May  patterns  1977 to  of c a p t i v e  December  California Social  1978.  i n t e r a c t i o n s between ewes were b r i e f i n duration and i n f r e q u e n t , r e l a t i v e to bighorn  rams.  displays. strongly  Aggressive  interactions  (butts)  were more common than horn  Although a dominance hierarchy was evident i n the herd, i t was not linear.  Age, horn length, and body weight  strongly c o r r e l a t e d to dominance.  were not  shown to be  The most dominant animals proved to be the  most aggressive, i n i t i a t i n g more i n t e r a c t i o n s than subordinate animals. presence  of  a lamb  Dominant status  appeared  to  improve  could not be shown to  the  social  positively  status  affect  of  The  some  ewes.  an animal's  diet,  a c t i v i t y budget or p r o d u c t i v i t y .  The herd's d i u r n a l a c t i v i t y pattern changed considerably on a seasonal The a c t i v i t y  pattern  was  characterized  periods i n spring and summer.  by  successive  feeding  and  basis. bedding  A c t i v i t y peaks generally d e c l i n e d i n number and  increased in duration during the f a l l and winter p e r i o d s .  The herd's d i u r n a l a c t i v i t y budget also varied s e a s o n a l l y . the  day devoted  actual  daylight  to  feeding  grazing  increased  times  were  The proportion of  with  decreasing  daylength,  poorly  correlated  to  although  daylength.  The  proportion of the day devoted to bedding was highest i n s p r i n g and summer, and to a l e s s e r extent,  i n mid-winter.  c o r r e l a t e d (r = 0.92) to daylength.  Actual  Both the actual  the day devoted to standing, t r a v e l l i n g minor seasonal f l u c t u a t i o n s .  bedding times were  and \"other\"  significantly  time and proportion of activities  showed only  It was shown that poor health i n herd members  ii i  \u000Caffected a c t i v i t y  budgets s i g n i f i c a n t l y .  be shown t o  significantly  rates  and d i u r n a l  (BMR)  affect activity  Late stages  activity costs  budgets.  o f pregnancy Average  were e s t i m a t e d  for  basal the  could  metabolic  herd.  BMR's and a c t i v i t y c o s t s were h i g h e r i n s p r i n g and e a r l y summer than a t times of the y e a r .  i v  not  Both other  \u000CTable of Contents Page Abstract  iii  L i s t of Tables  viii  L i s t of Figures  x  Acknowledgements  xi  INTRODUCTION  1  STUDY AREA  6  METHODS  7  F i e l d Procedures  7  Comparative A n a l y s i s - Methods and R a t i o n a l e A.  B.  Social  Organization  1.  Dominance h i e r a r c h y o f t h e a d u l t ewes  2.  Determinants o f dominance  8 10  Consequences o f Dominance 1.  D i e t comparisons  11  2.  A c t i v i t y budget comparisons  12  3.  P r o d u c t i v i t y comparisons  14  v  \u000CPage C.  Forage A v a i l a b i l i t y and Herd Behaviour  15  1.  Seasonal d i u r n a l p a t t e r n s  15  2.  Seasonal a c t i v i t y budgets  16  D.  E f f e c t s of P h y s i o l o g i c a l  C o n d i t i o n on A c t i v i t y Budgets  E.  Energy E x p e n d i t u r e E s t i m a t e s f o r t h e A d u l t Ewes  16 17  RESULTS A.  Social 1.  Organization  Dominance h i e r a r c h y o f t h e a d u l t ewes S t a b i l i t y o f t h e a d u l t ewes s o c i a l  2. B.  C.  21 system  Determinants o f dominance  25 26  Consequences o f Dominance 1.  D i e t Comparisons  29  2.  A c t i v i t y budget comparisons  30  3.  P r o d u c t i v i t y comparisons  33  Forage A v a i l a b i l i t y and Herd Behaviour  35  1.  39  Seasonal d i u r n a l p a t t e r n s Nocturnal a c t i v i t y  2.  47  Seasonal a c t i v i t y budgets  D.  E f f e c t s of P h y s i o l o g i c a l  C o n d i t i o n on A c t i v i t y Budgets  E.  Energy E x p e n d i t u r e E s t i m a t e s f o r t h e A d u l t Ewes  vi  49 54 56  \u000CPage DISCUSSION A.  Social 1.  Organization  Dominance h i e r a r c h y o f t h e a d u l t ewes S t a b i l i t y o f the a d u l t ewes s o c i a l  2. B.  C.  59 system  Determinants o f dominance  64 66  Consequences o f Dominance 1.  D i e t comparisons  70  2.  A c t i v i t y budget comparisons  72  3.  P r o d u c t i v i t y comparisons  75  Forage A v a i l a b i l i t y and Herd Behaviour  77  1.  78  Seasonal d i u r n a l  patterns  Nocturnal a c t i v i t y 2.  88  Seasonal a c t i v i t y budgets Daily v a r i a b i l i t y  90  i n herd b e h a v i o u r  95  C o n d i t i o n on A c t i v i t y Budgets  96  D.  E f f e c t s of P h y s i o l o g i c a l  E.  Energy E x p e n d i t u r e E s t i m a t e s f o r t h e A d u l t Ewes  98  SUMMARY  103  BIBLIOGRAPHY  107  vi i  \u000CL i s t of Tables  Table I  Page Dominance v a l u e s o f c a p t i v e ewes, based on d y a d i c interactions  II  23  Dominance v a l u e s o f c a p t i v e ewes, based on d y a d i c interactions  III  ( f o r p e r i o d June 1 - December 3 1 , 1977)  ( f o r p e r i o d January 1 - June 3 0 , 1978)  C o r r e l a t i o n between Dominance V a l u e s  24  ( D . V . ) and  p r e d i c t e d d e t e r m i n a n t s o f dominance: age ( A . ) , body w e i g h t (WT.), horn l e n g t h ( H . L . ) and a g g r e s s i v e n e s s (AG.)  ( i . e . number o f i n t e r a c t i o n s  initiated)  (June t o December, 1977) IV  27  C o r r e l a t i o n between Dominance Values ( D . V . ) and p r e d i c t e d d e t e r m i n a n t s o f dominance (January t o J u n e , 1978)  V  28  D i e t comparisons between Dominants, I n t e r m e d i a t e s and Subordinates  VI  31  Average d a y l i g h t f e e d i n g and bedding t i m e s Dominants, I n t e r m e d i a t e s and S u b o r d i n a t e s  for (September  1977 t o March 1978) VII  32  Seasonal weight change comparisons o f Dominants, I n t e r m e d i a t e s and S u b o r d i n a t e s  VIII  Mean c o v e r o f t h e major u n d e r s t o r y p l a n t s p e c i e s t h e 1977 s a m p l i n g p e r i o d (From Wikeem, i n p r e p . )  vi i i  34 over 36  \u000CTable IX  Page Average d a y l i g h t a c t i v i t y budgets of t h e a d u l t ewes, by month  Xa  50  Average d a y l i g h t g r a z i n g and bedding t i m e s o f h e a l t h y and s i c k ewes (October t o December 1977)  b  Average d a y l i g h t g r a z i n g and bedding t i m e s o f pregnant and non-pregnant ewes (March, A p r i l  XI  1978)  55  Average basal m e t a b o l i c r a t e s f o r t h e a d u l t ewes, by month  XII  55  57  Average d a y l i g h t energy e x p e n d i t u r e s f o r t h e a d u l t ewes, by month  58  ix  \u000CL i s t of  Figures  Figure  Page  Graphs of monthly d i u r n a l (May 1977 t o A p r i l  1978)  patterns of the captive  herd 40  x  \u000CAcknowledgements  Financial  support f o r t h i s study was p r o v i d e d by an NRC S c h o l a r s h i p t o t h e  a u t h o r and a Canadian W i l d l i f e S e r v i c e and NRC O p e r a t i n g Grant t o Dr. D.M. S h a c k l e t o n o f t h e U n i v e r s i t y o f B.C.  D r . Don Eastman, Research C o o r d i n a t o r  of  t h e B.C. F i s h and W i l d l i f e B r a n c h , must a l s o be g r a t e f u l l y acknowledged f o r h i s s u p p o r t d u r i n g t h e f i e l d program.  I t i s w i t h p l e a s u r e t h a t I thank D r . D.M. S h a c k l e t o n f o r h i s s u p p o r t and d i r e c t i o n d u r i n g t h i s s t u d y , as w e l l as my a d v i s o r y committee, D r s . M. F. B u n n e l l and D. Hebert f o r t h e i r s u g g e s t i o n s and t e c h n i c a l  aid.  Pitt,  A special  note o f thanks i s conveyed t o B r i a n Wikeem f o r s h a r i n g h i s b o t a n i c a l  expertise  and t o a l l members o f t h i s c o o p e r a t i v e study f o r t h e i r c o n t r i b u t i o n s t o my work.  Other i n d i v i d u a l s t o whom I extend my a p p r e c i a t i o n i n c l u d e Mr. E. Lacey and f a m i l y o f t h e Okanagan Game Farm f o r t h e major r o l e t h e y p l a y e d i n  providing  both t h e study s i t e and t h e study a n i m a l s and f o r t h e i r f r i e n d s h i p d u r i n g my f i e l d work, and Ms. C. Braun and Ms. P. P y l e f o r t h e i r e x c e l l e n t t y p i n g and word p r o c e s s i n g s k i l l s ,  respectively.  My warmest thanks a r e extended t o my p a r e n t s f o r t h e i r support and encouragement t h r o u g h o u t u n i v e r s i t y , and t o my w i f e , L i z and s o n , Aaron f o r t h e i r p a t i e n c e and f o r t h e weekends \" s a c r i f i c e d \" f o r t h e t h e s i s .  xi  \u000CINTRODUCTION  In t h e p a s t , r e s e a r c h i n t o t h e s o c i a l study  of  studied  behaviour in  dyadic  patterns  shown  interaction...\"  has been l i n k e d t o t h e e c o l o g y  b e h a v i o u r o f a n i m a l s was l a r g e l y a between  (Crook  conspecific  1970).  individuals  Recently,  and dynamics o f animal  social  populations  \"...  usually behaviour  (Eisenberg  1966, Crook 1970, G e i s t 1971, W i l s o n 1975, Crook et al_. 1976, Krebs and Davies 1978),  prompting  discussion  traits  as  size  group  s t r a t e g i e s of various  and  on t h e  ecological  cohesion,  social  implications organization  of  Estes  1967,  While  some  their  (Chevrotain  often  1974,  such  and  social  reproductive  species.  U n g u l a t e s have r e c e i v e d c o n s i d e r a b l e a t t e n t i o n because  of  obvious  Geist  ungulates tragulus)  1971, such  are  and  spectacular  Jarman  as  the  solitary  from s o c i o - b i o l o g i s t s ,  1974, moose  in  social  Kitchen (Alces  nature,  nature 1974,  alces)  generally  largely  (Geist  1971,  Sinclair and  1974).  chevrotain  associating  with  c o n s p e c i f i c s o n l y d u r i n g maternal and r e p r o d u c t i v e a c t i v i t i e s , t h e m a j o r i t y s p e c i e s demonstrate a s t r o n g tendency f o r h e r d i n g .  Frequently, a hierarchial  system has e v o l v e d t o e n a b l e c o n s p e c i f i c s  to coexist  minimum  of  group  studies  have  hostile shown  species (-cattle Espmark  1964;  interactions that  relatively  linear  in  mountain  sheep  (Ovis  dominance  canadensis,  social  members.  units  Social  orders  (Bos t a u r u s ) , Syme e t ^1_. 1979; r e i n d e e r  t h a t dominant s t a t u s i s p o s i t i v e l y and age.  between  exist  (Rangifer  0_. d a l l i ) ,  Geist  However, such s t u d i e s have c o n c e n t r a t e d on male s o c i e t i e s  with a  behaviour for  many  tarandus), 1971))  c o r r e l a t e d t o body s i z e , a n t l e r / h o r n  1  of  and size,  and t h e i r  \u000Creproductive  activities.  This  preoccupation  with  male  behaviour  is  not  s u r p r i s i n g , c o n s i d e r i n g t h e o f t e n s p e c t a c u l a r n a t u r e o f male i n t e r a c t i o n s , it  has  largely  female-nursery animals  of  ignored  groups.  both  sexes  the Since  occurs  significance the  in  social  the  of  and  company  the  infrastructure  behavioural  of  adult  the  s o c i e t y , by m o d i f y i n g t h e responses o f young a n i m a l s t o e n v i r o n m e n t a l is  o f fundamental  r e s e a r c h e r s have  importance t o p o p u l a t i o n provided  u n g u l a t e n u r s e r y groups 1978;  black-tailed  limited  information  (domestic l i v e s t o c k ,  deer  (Odocoileus  a r e a t o complete t h e s o c i o - b i o l o g i c a l  concept  of  consideration. territories  stimuli,  social  Some  behaviour  of  Hafez 1969, A r n o l d and D u d z i n s k i Miller  1974;  But more r e s e a r c h i s  pronghorn  needed i n  p i c t u r e o f many o t h e r u n g u l a t e  defended  reproductive,  individuals  foraging  (Wilson 1975), l e s s  advantages  r e f e r e n c e has been made t o t h e  superior  However,  this  again  statement  concentrated  That h i g h s o c i a l genetic  fitness  is  based  in  survival  W i l s o n (1975) summarizes t h a t \" w i t h r a r e e x c e p t i o n s , t h e a g g r e s s i v e l y d i s p l a c e s the subordinate  status  and/or  animals.  have  dominant  also  of  animal  of  systems  species.  W h i l e i t has been suggested t h a t occupants o f r i g i d l y  benefits  hierarchial  this  further  definite  in  female  and p r o d u c t i v i t y .  the  of  requires  have  over t r a n s i e n t ecological  dominance  on  hemionus),  ( A n t i l o c a r p a americana), Kitchen 1974).  The  stability  of  development  females,  but  free  from f o o d , largely  on a s p e c t s  of  ranging  from mates and from n e s t on i n f o r m a t i o n  male  interactions  rank i n female h i e r a r c h i e s a c t u a l l y is  more  speculative  and few  hypothesis.  2  groups  studies  from s t u d i e s (e.g.  improves an have  sites\".  Geist  which 1971).  individual's  investigated  this  \u000CThe  first  objectives  of  this  study  were  to  organization, and B) the apparent consequences of adult C a l i f o r n i a  bighorn ewes.  investigate:  A)  the  social  of dominance in a captive group  Hypotheses formulated and  tested  in the  investigation in t h e i r alternative ( H A ) , form included:  A.  Social Organization  1.  A  relatively  stable  linear  hierarchy would  be  established  amongst the  ewes.  2.  Age,  horn  size  and  body  size would  be  directly  correlated  to  social  status.  B.  1.  Consequences of Dominance  Dominant animals would, during months of limited available forage, have access to higher quality foraging areas and would, as a result, remain on a higher plane of nutrition than subordinate animals.  2.  Access  to  high  quality  foraging  areas  would  increase  intake  and  assimilation rates, reduce the daily grazing times and increase the daily bedding times of dominants over those of subordinates.  3.  Dominant ewes, because of t h e i r higher plane of n u t r i t i o n , would better survive the physiological stresses of winter and, as a r e s u l t , would be in better physical condition and have a higher reproductive output than ewes of lower social  rank.  3  \u000CThe need f o r comparable d a t a on t h e g r a z i n g t i m e s o f prompted an i n v e s t i g a t i o n  i n t o seasonal  individual  changes i n t h e d a i l y a c t i v i t y  o f t h e s e a n i m a l s as a second major r e s e a r c h o b j e c t i v e . researchers  o f domestic a n i m a l s  For s e v e r a l  have conducted such s t u d i e s  e f f e c t s of environmental  and p h y s i o l o g i c a l  and p r o d u c t i v i t y o f  free  ranging l i v e s t o c k  1960b,  1974, A r n o l d  1962, S q u i r e  herd members  decades,  t o determine  v a r i a b l e s on t h e f e e d i n g  declines  the  behaviour  (Meyer e t al_. 1957, A r n o l d 1960a,  and D u d z i n s k i  1978).  Studies  on  domestic  sheep (Ovis a r i e s ) , f o r example, have shown t h a t herd g r a z i n g t i m e s i n c r e a s e w i t h seasonal  budgets  i n range q u a l i t y and q u a n t i t y  generally  ( A r n o l d 1960a).  C o n v e r s e l y , t h e degree o f herd c o h e s i o n i n f r e e - r a n g i n g g r a z i n g animals  often  decreases  1967,  with  declining  D u d z i n s k i et ajk  1969).  range  conditions  Animal s c i e n t i s t s  (Dudzinski  and  Arnold  have a l s o r e p o r t e d t h a t g r e a t  daily  v a r i a t i o n i n b e h a v i o u r e x i s t s between i n d i v i d u a l  herd members s u b j e c t e d t o the  same  differences  environmental  physiological information  conditions  condition,  because  genetics,  on herd and i n d i v i d u a l  of  weight behaviour  and  forage  has,  in turn,  in  age,  sex,  selection.  Such  been employed  in  i n t e n s i v e range and animal management.  Similar  studies  on many w i l d  viewing conditions data  are  on  the  o f mountain  daily  duration Dyke  few  days  of a c t i v e  (1978)  of  sheep f o r  this  completed  a  more  natural  thorough  and  Various  of  poor  Few q u a n t a t i v e potential  energy  researchers  (Mills  for  study  the  time  several of  this  of  occurrence  different kind,  herds.  examining  a c t i v i t y p a t t e r n s o f ewes, lambs, and rams, and comparing t h e a c t i v i t y  4  the  have d e s c r i b e d herd a c t i v i t y  giving  periods  because  habitat.  patterns  reason.  1971)  observations,  and n o n - a c t i v e  difficult  activity  1937, D a v i s 1938, B l o o d 1963, G e i s t relatively  are  a f f o r d e d by t h e a n i m a l s '  available  expenditures  ungulates  from and Van the  budgets  \u000Cof the d i f f e r e n t  sex and age groups w i t h i n  w i l d p o p u l a t i o n s are u s u a l l y  seasons.  However,  f o r c e d t o observe d i f f e r e n t  days and even f l u c t u a t i n g numbers on t h e same day. animal  behaviour,  resulting  in  \"average  data\"  s p e c i f i c age and sex c l a s s e s o f a n i m a l s . activity  budgets  identifiable enable  potential  being  To f u l l y  energy  of  a n i m a l s on d i f f e r e n t obscures collected  individual even  for  understand and a s s e s s  the  expenditures  of  herd  members,  i n d i v i d u a l s must remain under o b s e r v a t i o n throughout t h e study t o  their  environmental and  and  This  researchers  daily  and p h y s i o l o g i c a l  accessibility  opportunities.  behaviour  of  the  to  factors  animals  As a r e s u l t ,  be  in  interpreted  with  mentioned above. this  t h e secondary  study  respect  to  The c a p t i v e  provided  research objectives  such  the state  research  of t h i s  study  were:  C.  To determine t h e e f f e c t s patterns,  o f f o r a g e c o n d i t i o n and season on 1) t h e  2) t h e a c t i v i t y  budgets o f a c a p t i v e  population of  diurnal  California  b i g h o r n ewes.  D.  To a s s e s s t h e e f f e c t s  of p h y s i o l o g i c a l  condition  on t h e d a i l y  activity  budgets o f t h e a d u l t ewes.  E.  To e s t i m a t e t h e r e l a t i v e mean d a i l y energy e x p e n d i t u r e s o f the a d u l t ewes on a monthly  basis.  5  \u000CSTUDY AREA  In  April  1977,  Penticton, sheep,  a  B.C.,  a  enclosure  adjacent  was c o n s t r u c t e d f o r  intensive  species  40  native  sloping grassland, zone  (Krajina  ha  falls  1969)  However,  the  within  and i s  rangeland occupied year population.  to  area. the  similar  The  in  study  area  the  both e l e v a t i o n  has  this  intermittent successional  study  commenced,  g r a z i n g from horses stage  (Wikeem,  the  a  of  spicatum).  had  comm.),  Estimates  being  steeply  t h e Vaseux  to  the  Lake  bighorn  eastern  aspect,  west-southwest.  received be i n  dominated  light,  a near  climax  by  bluebunch  (Agropyron  study s i t e  ( P i t t , Wikeem, p e r s . comm.) d i c t a t e d t h e s i z e o f t h e herd which was  6  the c a r r y i n g  only  wheatgrass  released i n t o the area.  of  on  biogeoclimatic  predominantly  enclosure  Farm, bighorn  and v e g e t a t i o n  and was c o n s i d e r e d t o  pers.  situated  Pine-Bunchgrass  groups  Game  on C a l i f o r n i a  enclosure,  d i f f e r i n g from t h e Vaseux range which f a c e s p r i m a r i l y  Before  Okanagan  studies  Ponderosa  round by maternal the  to  capacity  of  the  \u000CMETHODS  Field  Procedures  From January t o March, 1977, a drop net was used a t t h e Vaseux Lake bighorn  range,  20 km south o f P e n t i c t o n ,  t h e study s i t e . captured  A total  to  o f 16 ewes, t h r e e  and t r a n s p o r t e d  capture  animals  observations  t o t h e Game Farm.  for this  f o r 14 c o n s e c u t i v e months.  research  at  lambs, and one y e a r l i n g male were Before  being  released  e n c l o s u r e i n A p r i l , each animal was f i t t e d w i t h an i d e n t i t y  Behavioural  for  California  into  the  collar.  study commenced i n May, 1977 and c o n t i n u e d  Most o b s e r v a t i o n s were made t h r o u g h a 20-40 x 60  zoom b i n o c u l a r s p o t t i n g scope from a p o i n t 200 m e a s t o f t h e l o w e r boundary o f t h e e n c l o s u r e where t h e eliminated  any  When  animals  the  obvious  majority  of  disturbance  occupied  the  the to  A l t h o u g h water and m i n e r a l corner  of  the  wheatgrass-big  site  animals  could  be viewed.  during  corner  sampling  of  periods. enclosure,  timbered area approximately  50 m n o r t h  site.  the  (Artemi s i a  e n c l o s u r e as a food s o u r c e .  sheep  were  dependent  tridentata)  As a r e s u l t ,  plant  their  i n the  northeast  the  bluebunch  on  community  daily  activity  within  the  patterns  were  c o n s i d e r e d t o be r e p r e s e n t a t i v e o f f r e e r a n g i n g a n i m a l s on b o t a n i c a l l y ranges,  particularly  migrations. made f o r a g i n g  those  This  the  b l o c k s were p r o v i d e d a r t i f i c i a l l y  enclosure, sage  the  northwestern  o b s e r v a t i o n s were made from a l i g h t l y o f t h i s p o r t i o n o f t h e study  study  populations  not  exhibiting  seasonal,  similar vertical  In l a t e December and throughout J a n u a r y , c r u s t e d snow c o n d i t i o n s difficult  for  the  sheep  7  and s e v e r a l  mortalities  prompted  the  \u000Cdistribution  of  supplemental  Approximately  45 kg o f hay was p r o v i d e d a t dusk each day.  c o l l e c t e d during t h i s artificial  hay  near  the  water  and  mineral  supply.  Behavioural  p e r i o d were i n t e r p r e t e d w i t h due c o n s i d e r a t i o n  data  for  the  feeding s i t u a t i o n .  Comparative A n a l y s i s - Methods and R a t i o n a l e  A.  Social  1.  To  Organization  Dominance h i e r a r c h y o f t h e a d u l t ewes  determine  the  observations  of  social  dyadic  relationships interactions  s a m p l i n g (Altmann 1 9 7 4 ) . to y i e l d  unbiased d a t a ,  that  behavioural  all  likelihood social  of  had  were  between  collected  the  captive  primarily  by  ewes,  ad  1ibitum  Two assumptions n e c e s s a r y f o r such a s a m p l i n g scheme and c o n s i d e r e d  patterns  used  b e i n g observed and,  class  existing  equal  in  from ad 1 i b i t u m  incidentally  during  scan  during  dominance  interactions  b) t h a t  likelihood  interactions  fulfilled  of  the being  s a m p l i n g were  sampling  periods,  interactions observed.  supplemented a  the  sampling  study  were,  had an  of  ewes  equal  of  Observations by  those  method  a)  each of  collected  discussed  in  S e c t i o n B2 o f Methods and R a t i o n a l e .  Information  recorded  for  i n i t i a t o r and r e c e i v e r ,  each  interaction  included  the  identities  into  the  b e h a v i o u r p a t t e r n s used by both as d e s c r i b e d by G e i s t  (1971) and S h a c k l e t o n ( 1 9 7 3 ) , and t h e n a t u r e o f t h e i n t e r a c t i o n . were c l a s s i f i e d  of  one o f  five  categories:  8  bedding,  feeding,  Interactions positional,  \u000Cplayful  or  unclassified  classification  (where  interaction  was  already  in  progress,  making  impossible).  A \"dominant\" animal was d e f i n e d as an i n d i v i d u a l which d i s p l a c e d a f e l l o w herd member  from  individual  a to  information  resource which  was  (i.e.  bedding  subordinate  tabulated  in  site,  behaviour  two  feeding  (Geist  interaction  site,  1971)  etc.),  or  as  was d i r e c t e d .  matrices  of  an This  \"Dominants\"  and  \" S u b o r d i n a t e s \" , t h e f i r s t c o n t a i n i n g d a t a c o l l e c t e d from June 1977 t o December 1977; t h e second c o n s t r u c t e d from d a t a g a t h e r e d from J a n u a r y 1978 t o June 1978 after  the s t r u c t u r e  of  the  herd had been a l t e r e d  by m i d - w i n t e r  mortalities.  The c e l l s o f each m a t r i x c o n t a i n e d t h e number and outcome o f d i s p u t e s between animal  every  pair  was then  of  herd members  for  ranked a c c o r d i n g t o t h e  that  particular  number and i d e n t i t y  members t h a t i t had dominated and had been dominated b y . born on s i t e since  the  i n 1977 nor t h e t h r e e y e a r l i n g s  majority  interpret.  of  A Dominance  their  interactions  Value  (D.V.  were  socially  rank  individuals  within  of  \\/x&gt; where  Each  fellow  herd  N e i t h e r t h e 18 lambs  play-like  and x  analyses  difficult  to  = proportion  of  1966)) was determined f o r each animal  from t h e p r o p o r t i o n o f opponents t h a t i t dominated. to  period.  were i n c l u d e d i n t h e s e  = arcsin  opponents dominated (see B e i l h a r z e t a K  time  occuring  a group  of  D . V . ' s have been employed  animals  in  situations  where  such a p r o c e s s i s not p o s s i b l e from a q u a n t a t i v e a n a l y s i s o f d y a d i c e n c o u n t e r s alone,  either  interactions  because  of  between c e r t a i n  dominance pairs  t h e c a p t i v e h e r d ; see R e s u l t s ) . sufficient  circles  of  or  animals.  a  lack  of  (Such a s i t u a t i o n  P r o v i d i n g each herd member i s  and comparable number o f  interactions,  a D.V.  each a n i m a l , r e g a r d l e s s o f t h e i d e n t i t y o f i t s opponents.  9  actual  social  arose  for  involved in a  can be a s s i g n e d In a d d i t i o n ,  to  these  \u000Cvalues,  once  converted  distributed,  enabling  least-square  t h r e e measures o f s o c i a l  classes groups,  Several  (angular D . V . ' s ,  D.V.'s).  dominance\".  an  arcsin  parametric  parameters t o be made. been developed  by  correlations different  Beilharz  of  the  (Wilson 1975).  et  &lt;fL  Dominance  (1966)  found  identical  linearity  three  and  ...\"the  distinct of  Subordinates,  In f o r m u l a :  h  12  linearity x  (Va -  social  these is  of  three  given  in  for  any g i v e n  an index hierarchy  n-l)? 2  index  n = t h e number o f animals i n t h e study  group  Va = t h e number o f group members t h a t t h e a  t n  animal  V a l u e s range from 0 t o 1, w i t h 1 i n d i c a t i n g a c o m p l e t e l y l i n e a r  dominates  order.  Determinants o f dominance  To determine i f p r e d i c t e d m o r p h o l o g i c a l c r i t e r i a were i m p o r t a n t i n  body  have  D.V.'s,  that  was a l s o determined f o r each h i e r a r c h y ,  a measure o f t h e degree o f  where h = L a n d a u ' s  social  biological  evaluations  A description  n3-n  2.  and  estimating D.V.'s  Values,  ewes.  Intermediates  rank  normally  Results.  Landau's i n d e x o f which p r o v i d e s  Dominants,  become  study, weighted angular  dominance gave p r a c t i c a l l y  were r e c o g n i z e d among t h e a d u l t  Section A ( l ) of  between  methods o f  used i n t h i s  However,  From a n a l y s i s  labelled  transformation,  rank i n t h e a d u l t weights  and  horn  ewes, ages lengths  were  ( e s t i m a t e d by horn a n n u l i collected  10  from  each  determining  (Geist  animal  four  1966)), times  \u000Cduring August,  the  course  1978).  of  the  study  (September  The degree o f c o r r e l a t i o n  and December,  1977, March  between Dominance Values  and  and age,  mean w e i g h t s and horn l e n g t h s was determined f o r t h e herd members i n each o f the  hierarchies.  To  investigate  the  importance  of  behavioural  as  well  as  morphological  parameters t o dominance, t h e number o f a g g r e s s i v e e n c o u n t e r s i n i t i a t e d by each i n d i v i d u a l was t a l l i e d f o r both t h e 1977 and 1978 h i e r a r c h i e s . correlation  between  these  totals  and r e s p e c t i v e  Dominance  The degree o f  Values  was  then  assessed.  A level  o f 5% probability  statistical  B.  for this  and a l l  subsequent  analysis.  Consequences o f Dominance  1.  Two  was e s t a b l i s h e d a p r i o r i  Diet  comparisons  separate  classes  of  \"preference\"  approaches ewes.  In  were  taken  January,  to  1978,  f o r t h e supplemental  compare the  hay o v e r  herd  approach  to  (Capreolus capreolus)  that  of  Espmark's  and r e i n d e e r ,  of  the  (1974a,  three  demonstrated  t h e more abundant  d e p l e t i n g t h e hay s u p p l y b e f o r e s t a r t i n g t h e i r similar  diets  an  apparent  range  forage,  grazing routine. 1974b)  t h e mean d a i l y  studies  dominant  ewes  would  Following a on  roe  t i m e spent by each  c l a s s consuming hay was compared (method o f d a t a c o l l e c t i o n w i l l in a later section).  social  social  be d i s c u s s e d  A S t u d e n t ' s t - t e s t was used t o t e s t t h e h y p o t h e s i s gain  greater  access  i n t e r m e d i a t e o r s u b o r d i n a t e ewes.  11  to  the  \"preferred\"  deer  feed  that than  \u000CUse o f diet  fecal  nitrogen  comparisons.  (N) l e v e l s was t h e  Hebert  (1973)  c o r r e l a t e d t o crude p r o t e i n sheep.  Recognizing  different Mean  N  social  this  status  levels  in  found  and energy  fact,  second,  fecal  fecal  levels  feces  of  N levels of  samples  during recaptures  more i n d i r e c t ,  forage  were  were  then  consumed by  bighorn  from  compared  to  positively  ewes  1977 and March,  i n t e r m e d i a t e and s u b o r d i n a t e ewes, a g a i n u s i n g S t u d e n t ' s  2.  be  collected  i n December,  dominants  to  approach  to  of  1978.  those  of  t-test.  A c t i v i t y budget comparisons  Comparisons o f t h e mean d a i l y classes  of  studies.  ewes Arnold  were  g r a z i n g and bedding t i m e s  conducted  (1960a)  based  on  that  the  showed  the  of  findings  grazing  of  time  the three  social  domestic  animal  of  domestic  sheep  i n c r e a s e d and r u m i n a t i n g t i m e decreased w i t h d e c r e a s i n g p a s t u r e q u a l i t y .  For  t h i s s t u d y , i t was p o s t u l a t e d t h a t dominant ewes w o u l d , i n g e n e r a l , f o r a g e on higher q u a l i t y  v e g e t a t i o n and, as a r e s u l t , would demonstrate reduced  feeding  t i m e s and g r e a t e r bedding t i m e s than i n t e r m e d i a t e and s u b o r d i n a t e ewes f o r c e d i n t o more m a r g i n a l l y n u t r i t i o u s  areas.  Scan  was  sampling  (Altmann  1974)  and l o c a t i o n s  used of  to  collect  individual  data  ewes  for  on  the  this  activity  durations,  movements  comparative  analysis.  D u r i n g t h r e e t o seven s a m p l i n g days per month, t h e study s i t e was  scanned every 15 minutes from dawn t o dusk and t h e a c t i v i t y o f each  individual  was n o t e d , t o g e t h e r w i t h i t s quadrat l o c a t i o n t a k e n from a g r i d d e d map o f area. its  A l t h o u g h each animal was observed  activity,  scan o f  the  Activities  seconds t o  determine  a p p r o x i m a t e l y two t o t e n minutes were r e q u i r e d f o r a  complete  herd,  for  depending on t h e degree  were c a t e g o r i z e d as f e e d i n g ,  12  of  only  five  the  herd d i s p e r s i o n  bedding,  travelling  and movement.  without  feeding,  \u000Cs t a n d i n g and o t h e r ( p l a y , s o c i a l these a c t i v i t i e s animal. to  during the d a y l i g h t  grooming).  The time devoted t o  hours was c a l c u l a t e d  each day f o r  each  Only d a t a c o l l e c t e d on f e e d i n g and bedding t i m e s from September, 1977  March,  1978  were  utilized  assumed t h a t h i g h q u a l i t y that  interactions,  competition  between  for  this  particular  analysis,  since  f o r a g e would o n l y be l i m i t e d d u r i n g t h i s conspecifics  would  be  evident  only  it  was  p e r i o d and  during  this  period.  The v a r i a t i o n  the  different  social  c l a s s e s o f a d u l t ewes was a s s e s s e d each month by a n a l y s i s o f  variance,  using  a  two  i n t h e mean d a i l y  factor  nested terms.  Y  ijk  where  =r  analysis  f e e d i n g and bedding t i m e s  with  one  interaction  term  of  and  an  unbalanced  In l i n e a r model form:  +  G  i  +  D  J  +  (  G x D  )iJ  +  N  K(i)  L\"(  +  G x D  )ijxN  K ( i )  ]  d a y l i g h t time devoted t o g r a z i n g (or bedding)  Yijk  herd mean social  Gi D  group.effect  s a m p l i n g day e f f e c t  j  (three  levels)  ( t h r e e t o e i g h t l e v e l s , depending on  month (GxD)ij  group x day i n t e r a c t i o n animal w i t h i n s o c i a l  Vi)  term  group e f f e c t  (unbalanced nested  term). L e v e l s o f t h e nested terms d e c r e a s e d s l i g h t l y as t h e study p r o g r e s s e d because o f m o r t a l i t i e s and herd r e d u c t i o n . (GxD)ijx N  k ( i )  =  e x p e r i m e n t a l e r r o r term  The LSM 76 computer program (Harvey, 1977) was used f o r t h e a n a l y s i s .  13  \u000C3.  Productivity  comparisons  S e v e r a l p r o d u c t i o n parameters were used t o compare t h e b i o l o g i c a l ewes  of  different  parameter. quality  It  forage  animals. weight  of  status.  was h y p o t h e s i z e d would m a i n t a i n  To t e s t  loss  social  this  dominant  r e m a i n i n g two s o c i a l  that  Seasonal  weight  dominant  animals,  a more c o n s t a n t  hypothesis,  the  ewes was compared  classes.  change  was  with  access  body weight  average  October  (t-tests)  \"fitness\"  than  to  to that  one  such  to  high  subordinate  December, of  of  1977  each o f  the  S i m i l a r l y , mean w e i g h t g a i n s between March and  A u g u s t , 1978 were a l s o compared.  In each c a s e , w e i g h t changes were e x p r e s s e d  as a p r o p o r t i o n o f t h e o r i g i n a l weight ( i . e . October and March w e i g h t s ) .  Unexpected m o r t a l i t i e s  i n t h e herd i n December,  comparison  between s o c i a l  test,  of  fitness  t h e observed f r e q u e n c i e s  compared t o expected v a l u e s .  of  groups.  deaths  1977 a l l o w e d an a^ p o s t e r i o r i U s i n g a Chi'2 goodness  from t h e t h r e e  social  classes  Expected v a l u e s were c a l c u l a t e d from t h e  number o f deaths and t h e p r o p o r t i o n o f a n i m a l s i n each s o c i a l  R e p r o d u c t i v e measures were used as a t h i r d c o m p a r i s o n .  dams  on  birthweight  and  survival  of  the  Research on  neonate  fit were total  class.  nutrition  i n domestic sheep has demonstrated t h e s i g n i f i c a n c e o f pre-partum d i e t of  of  (Alexander  T h e r e f o r e , one may e x p e c t a dominant ewe, by m a i n t a i n i n g a h i g h e r  quality 1961).  nutritional  p l a n e than s u b o r d i n a t e a n i m a l s , t o be r e p r o d u c t i v e l y more s u c c e s s f u l  than t h e  1atter.  In 1978, when o n l y f i v e o f t h e t e n p o t e n t i a l l y t h e e x p e c t e d and observed f r e q u e n c i e s o f b i r t h s  14  p r o d u c t i v e ewes produced lambs, from t h e t h r e e s o c i a l  classes  \u000Cwere  compared  by  a Chi2  goodness  c a l c u l a t e d from t h e t o t a l  of  fit  test.  Expected  frequencies  were  number o f lambs produced and t h e number o f ewes  each c l a s s c o m p r i s i n g t h e h e r d .  T h i s was not p o s s i b l e  c a p t i v e ewe produced a t l e a s t one lamb.  for  B i r t h weights  1977, s i n c e  of  every  o f t h e lambs were not  a v a i l a b l e f o r comparison.  C.  Forage A v a i l a b i l i t y  Information  on f o r a g e  and Herd B e h a v i o u r  availability  and s e l e c t i o n  by t h e  sheep was  from t h e v e g e t a t i o n study o c c u r r i n g s i m u l t a n e o u s l y w i t h t h i s (Pitt to  and Wikeem 1979, and u n p u b l i s h e d d a t a ) .  consider  the  effect  of  range  phenology  behavioural  Consequently,  and animal  available  diet  it  work  was  possible  on t h e  activity  p a t t e r n s and budgets o f t h e h e r d .  1.  As  Seasonal d i u r n a l  described  information  in  on t h e  s a m p l i n g day i n other  than  Section  patterns  B2  diurnal  of  activity  at  each  d a y l i g h t p e r i o d was c a l c u l a t e d .  the  year.  consecutive peak.  scan  patterns  a month, t h e p r o p o r t i o n  bedding)  t h e mean d a i l y  Methods,  15  minute  than  sampling  Similarly,  50% o f intervals  was  of  members.  the  herd herd  sampling  used  active  to For  (all  interval  collect every  activities  throughout  the  These v a l u e s were, i n t u r n , used t o determine  number and d i s t r i b u t i o n  More  of  sampling  the  of  herd  (i.e.  activity  had t o  30 m i n u t e s )  be  peaks active to  for for  at  constitute  a n o n - a c t i v e p e r i o d was r e c o g n i z e d o n l y  if  t h e herd remained bedded f o r at l e a s t two c o n s e c u t i v e s a m p l i n g  15  every month  an  least  of two  activity  50% o r more intervals.  of  \u000C2.  The  Seasonal a c t i v i t y  activity  data  budgets  collected  during  each  15  e n a b l e d seasonal t r e n d s i n t h e d a i l y  activity  be  daylight  monitored.  Estimates  of  total  minute  scan  sampling  interval  budgets o f t h e herd members times  (in  hours)  devoted  to to  f o r a g i n g , b e d d i n g , t r a v e l l i n g , s t a n d i n g and \" o t h e r \" a c t i v i t i e s were determined each day by summing t h e number o f activity  was  observed  and  15 minute  dividing  by  sampling i n t e r v a l s  four.  Mean  daily  values  c a l c u l a t e d f o r each ewe and f o r t h e herd as a whole on a monthly  Using  a  high  intensity  spot  m o n i t o r e d on f o u r o c c a s i o n s t o determine t h e e x t e n t could  not  be  lamp  and  during  such  i n c l u d e d i n monthly a c t i v i t y budget  D.  E f f e c t s of P h y s i o l o g i c a l  Activity animals  budget of  comparisons  different  spotting  activity. observations  tissue these  comm.)  catabolism, high  in six  levels  died  then  the  herd  was  individual  night  data  1978)  animals were  not  determinations.  C o n d i t i o n on A c t i v i t y  Budgets  were  October  to  April  between  Analysis  of  blood  samples  conducted  physiological  showed e l e v a t e d  and  an  basis.  scope,  However,  from  condition.  c o l l e c t e d from t h e ewes i n t h e September-October pers.  were  (May 5, June 2 0 , November 14, December 17,  of n i g h t - t i m e  identified  the  i n which  levels  ewes. during  of  SGOT,  r e c a p t u r e program  an enzyme  With one e x c e p t i o n , December  d u r a t i o n s o f t h e s e moribund a n i m a l s  or  January.  (Peterson,  indicative  all  ewes  Grazing  of  body  demonstrating and  bedding  i n t h e t h r e e months p r i o r t o t h e i r  death  were compared t o t h o s e o f h e a l t h y a n i m a l s w i t h i n t h e i r r e s p e c t i v e s o c i a l  class  by S t u d e n t ' s  t-test.  16  \u000CF e e d i n g and bedding t i m e s o f pregnant and non-pregnant  ewes were compared  March and A p r i l , t h e two f i n a l months o f pregnancy when f e t a l greatest. social  S i m i l a r to the f a l l  class  were compared t o  prevent  demands would be  o n l y d a t a from ewes o f t h e  factor  confounding.  same  Student's  t-test  l i t e r a t u r e a v a i l a b l e on mountain sheep (Chappel  1978),  was a g a i n t h e s t a t i s t i c a l  E.  comparisons,  in  method u s e d .  Energy E x p e n d i t u r e E s t i m a t e s f o r t h e A d u l t Ewes  Using the bioenergetic  d o m e s t i c sheep (Graham 1964, C l a p p e r t o n 1961, i n Moen 1 9 7 3 ) , r e i n d e e r 1962, i n Moen 1 9 7 3 ) , and deer (Moen 1 9 7 3 ) , t h e mean d a i l y a c t i v i t y t h e herd were c o n v e r t e d t o mean d a i l y month. sheep  Chappel which  respectively), gross  energy  energy  expenditure  (1978) developed a p r e d i c t i v e  estimates  fasting  and  resting  given the sex, weight,  metabolic  nutritional  i n t a k e of the animal, date of  the t r i a l ,  o v e r a l l model, i n f o r m a t i o n on a l l study.  Monthly  temperatures. temperature,  five  km  were t a k e n  from  The mean t e m p e r a t u r e while  the  monthly  (FMR  the  study  and  and and  low p r e d i c t i v e v a l u e i n t h e  from i n t e r p o l a t e d  site,  temperature  RMR,  temperature  points  provided  was  this on a  Weather d a t a from t h e the  on s a m p l i n g days was used as  mean  each  bighorn  o f t h e above f a c t o r s was a v a i l a b l e f o r  mean ewe w e i g h t s  airport,  for  of  With t h e e x c e p t i o n o f  graph o f w e i g h t s o b t a i n e d d u r i n g f i v e c a p t u r e programs. Penticton  for  (fed or fasted)  trial  mean ambient t e m p e r a t u r e t h r e e days p r i o r t o t h e t r i a l . g r o s s energy i n t a k e v a l u e s , which had a r e l a t i v e l y  model  rate  status  budgets  estimates  bioenergetic  (Hammel  used  as  on a  given  necessary the  the  trial  ambient  temperature.  To  determine  the  daily  energy  various conversion factors  expended  by  an animal  activity,  have been d e v e l o p e d which a r e g e n e r a l l y a p p l i e d  17  to  \u000Ct h a t a n i m a l ' s basal m e t a b o l i c r a t e . energy c o s t when an animal post  absorptive  condition  to  retention  times  i s at rest i n a thermoneutral  condition\"  achieve of  in  Basal m e t a b o l i s m , d e f i n e d as \"the minimal  (Brody  ruminants  food  in  the  in  Moen  1973),  during metabolic  ruminant  a n i m a l s t o s t a n d r a t h e r than l i e measured from f a s t e d a n i m a l s  1945,  stomach  in metabolic  (36 -  72 h r s )  environment and i n a  research  and t h e  generally  a  because o f  long  of  study  As a r e s u l t ,  FMR's  in a standing  position,  ( B l a x t e r , 1962).  FMR v a l u e s minus t h e added c o s t s o f s t a n d i n g  on C h a p p e l ' s f i n d i n g s ) were used as e s t i m a t e s o f BMR v a l u e s i n t h e o f d a i l y energy  difficult  tendency  chambers.  have been more r e c e n t l y used as an a p p r o p r i a t e e q u i v a l e n t t h i s s t u d y , average d a i l y  is  (based  calculation  expenditures.  Energy c o n v e r s i o n f a c t o r s f o r a c t i v i t i e s were t a k e n from v a r i o u s s o u r c e s . additional Kg-1  and  Kg-1  BMR  hr-1)  Kcal  Graham  in was  Moen used  the  work  animals  standing  Kcal  bedding  above  BMR in  study.  at  the  while  were  and  rate  of  research  of  the  majority  5 km h r l . _  Clapperton's  (0.59 all  Kcal.  Kg-1  travelling  of  This  (0.24 (8  respectively.  that  Kcal  increments  the  costs  The  were  increments  running from  assumed  (0.22  respectively)  taken  fulfilled  ewes  ruminating  walking was  for  hr-1,  times  of It  (an assumption  feeding  Moen 1 9 7 3 ) ,  estimate  this  walked  1978)  to  (1962,  and  Kg-1  (Chappel  hr-1)  1973) in  both  0.43  and Hammel  done a l o n g c o n t o u r s that  of  applied  Kg-1  (1964)  (1961, Km-1)  costs  from C h a p p e l ' s  Kcal. x  energy  hr-1  taken  In  the  negated  f o r e s t i m a t e s o f t h e d i s t a n c e t r a v e l l e d by t h e a n i m a l s , v a l u e s not  was  time)  and  the  need  confidently  o b t a i n e d from t h e d a t a c o l l e c t e d , and c o n v e r t e d t h e energy c o s t s o f w a l k i n g t o Kcal  Kg-1  playing) Kcal  hr l. _  Costs  of  activities  were e s t i m a t e d from Moen's  Kg-1  hr l). _  Pregnancy  labelled  (1973)  conversion  and  lactation  18  \"other\" factor  (interacting, f o r play  demands  were  (3xBMR also  \u000Cc o n s i d e r e d , u s i n g approximate energy e x p e n d i t u r e s p r e s e n t e d i n Moen (1973) such l e v e l s  of  requirements  production.  Moen e s t i m a t e s  that  (1.08 x a c t i v i t y costs)  to  costs)  (1.31  x activity  during  peak  months ( A p r i l  The average  lactation  f o r pregnancy, May f o r peak l a c t a t i o n )  total  energy  expended  during  the  each month and c o n v e r t e d t o an h o u r l y  with  one fawn.  in this  daylight  rate  of  of  energy  expended  on  each  activity  study.  hours  was  consumption.  during  The  appropriate  determined This  was then e x p r e s s e d as a m u l t i p l e o f t h e h e r d ' s mean FMR f o r t h a t month. proportion  This  by t h e end o f g e s t a t i o n and  m u l t i p l e s i n b r a c k e t s were a p p l i e d t o d a i l y energy e x p e n d i t u r e s i n  for  maintenance  (normal d a i l y a c t i v i t y c o s t s ) a r e a p p r o x i m a t e l y 1.42 x BMR.  m u l t i p l e i n c r e a s e s t o 1.52 1.86  a 60 kg d e e r ' s  for  the  day  value The  was  also  estimates  were  c a l c u l a t e d each month.  The g e n e r a l as  calculation  procedures  f o r t h e energy e x p e n d i t u r e  follows:  Activity  Grazing  Equation  QGi = [BMR-j + 0.43 ( W t i ) ] T i G  Bedding-ruminating Walking  Vi  =  C B M R i  +  \u00B0*  2 4  (  W  t  i  )  ]  T  B/Ri  QWi = [BMRi + 0.59 (Wtj)V] Twi  (5 km/hr) Running  QRi = [BMRi + 8.0 (BMRi)] R-j  Standing  QSi = [BMRi + 0.22 ( W t i ) ]  \"Other\"  T  Activities  QOi = [BMRi + 3 (BMRi)]  19  T  Qi  T i S  \u000Cwhere QQI , Q  B / R i  ,  QWi, QR1, Q S i , QOi = average  d a y l i g h t energy expended on g r a z i n g , b e d d i n g / r u m i n a t i n g , w a l k i n g , r u n n i n g , s t a n d i n g and \" o t h e r \" a c t i v i t i e s , ith  m o n  th  r e s p e c t i v e l y , during the  (Kcal).  BMR-j = average d a y l i g h t energy expended on b a s a l metabolism d u r i n g t h e i t h month ( K c a l  hr-1).  Wti = average w e i g h t o f a d u l t ewes d u r i n g t h e i t h month (kg)  V  T  Gi,  = v e l o c i t y of t r a v e l  T  B/Ri'  T  Wi\u00BB  T  Ri,  T  (5 km h r l ) . -  S i , Toi = average  daylight  t i m e devoted t o g r a z i n g , b e d d i n g / r u m i n a t i n g , w a l k i n g , r u n n i n g , and \" o t h e r \" a c t i v i t i e s ,  standing  r e s p e c t i v e l y , d u r i n g t h e i t h month ( h r s ) .  N.B. - C o n v e r s i o n f a c t o r s f o r g r a z i n g , b e d . / r u m . , and s t a n d i n g have u n i t s Kcal k g - 1 h r - 1 . - C o n v e r s i o n f a c t o r s f o r r u n n i n g and \" o t h e r \" a c t i v i t i e s  are  - C o n v e r s i o n f a c t o r s f o r w a l k i n g has u n i t s o f K c a l k g  km-1.  20  - 1  unitless.  of  \u000CRESULTS  A.  Social  1.  A total These  Organization  Dominance h i e r a r c h y o f t h e a d u l t ewes  o f 180 i n t e r a c t i o n s between a d u l t ewes were observed d u r i n g t h e s t u d y . interactions  demonstrated  a very  three  different  most  common  followed usually  in  were t y p i c a l l y limited  patterns  pattern  used  frequency  to  squat,  in  behavioural the by  by t h e  urinate  sudden,  brief  repertoire,  majority  of  dominants  to  horn  displace  threat.  The  i n t e r a c t o r s would l o c k  horns and push o r t w i s t  butt,  regardless of the d i f f e r e n c e  Almost i n v a r i a b l y dominant.  Other  only  Butting  subordinate  subordinate's  and then move from t h e  f o l l o w e d by s e v e r a l  (&lt; 10 s ) .  performing  interactions.  However, m i l d c l a s h e s ,  initial  encounters  area,  or  Ewes two  was  the  animals,  response  to  or  simply  was flee.  seconds o f horn w r e s t l i n g i n which heads, o f t e n r e s u l t e d from t h e  in social  rank o f t h e  interactors.  (&gt; 90%), t h e i n i t i a t o r o f such an e n c o u n t e r was t h e e v e n t u a l patterns  subordinates  included  occasionally  displayed  the  used low  infrequently stretch  head shakes  and  or t h r e a t  by  dominant  kick. jumps a f t e r  ewes  towards  Subordinate  animals  being displaced  by  dominants and, on two o c c a s i o n s , were observed n u z z l i n g more dominant a n i m a l s .  Of t h e f i v e c a t e g o r i e s o f i n t e r a c t i o n s , e n c o u n t e r s a t bedding s i t e s were t h o s e most f r e q u e n t l y observed throughout t h e y e a r , c o m p r i s i n g 60 (33.3%) o f t h e 180 interactions  recorded.  at feeding s i t e s , Positional  Fifty-one  interactions  i n c l u d i n g t h e supplemental  interactions  arose p r i m a r i l y  21  (28.3% o f t h e t o t a l )  occurred  m i n e r a l , w a t e r and feed s o u r c e s .  when s u b o r d i n a t e  animals  appeared  to  \u000Cviolate 1979)  the of  \"individual more  dominant  established t r a i l s dominant this  (Hediger  ewes,  or  when  Forty-six  Playful  (25.6%)  interactions  of  normally  patterns  (jumps,  observed i n d a i l y  most  frequency the  fall  prevalent as t h e  remaining disputes  in  10  interactions  bursts  of  running,  spring  (late  Because  7.2% (13)  of  interactions  typical  of  of  all  this adult  (5.5%)  bighorn  rams  were  usually  by more were  be t h o s e encounters  of not  erratic  horn t h r e a t s )  Such i n t e r a c t i o n s  not  between  b e h a v i o u r o f y e a r l i n g s and lambs, March  to  June),  trend,  encounters  for  playful  off  in  during  interactions  the e n t i r e year.  unclassified. 1971,  tapering  rare to non-existant  seasonal  (Geist  blocked  classified  exaggerated  maintenance b e h a v i o u r .  the  Syme and Syme  P l a y was c h a r a c t e r i z e d by  summer p r o g r e s s e d and becoming  and w i n t e r .  comprised o n l y  in  unintentionally  were c o n s i d e r e d t o  a d u l t ewes, u s u a l l y i n i t i a t e d by t h e p l a y f u l were  animals  all  associated with resources or p o s i t i o n i n g . behaviour  1950, d i s c u s s e d  d u r i n g herd movements and were d i s p l a c e d ,  animals.  type.  distance\"  Ritualized  Shackleton  1973)  The  dominance were  not  observed d u r i n g t h e 14-month s t u d y .  In a d d i t i o n t o b e i n g o f b r i e f a l s o so i n f r e q u e n t observed. II)  that  duration,  encounters  interactions  between some p a i r s  between a d u l t of  a n i m a l s were  never  As a r e s u l t , s e v e r a l c e l l s o f each i n t e r a c t i o n m a t r i x (Tables I and  contain  no  p a i r s o f ewes.  information  on  the  social  relationships  between  (WWW, W,  dominant  over  Dominance V a l u e s , r a n g i n g from 65.9 t o 9 0 . 0 .  22  much o f  the  in  groups f o r both  F o r t h e June t o December, 1977, s a m p l i n g p e r i o d ( T a b l e I ) , RWB, WW) were  rank  An e v a l u a t i o n o f t h e Dominance V a l u e s ,  t u r n , showed t h e e x i s t e n c e o f t h r e e r e l a t i v e l y d i s t i n c t s o c i a l time p e r i o d s .  particular  However, computation o f Dominance V a l u e s enabled a s o c i a l  t o be a s s i g n e d t o each i n d i v i d u a l .  ewes  ewes were  herd  and  had  four high  Three ewes (WBW, NCA, W/R) were  \u000CTable I. Dominance Values of captive ewes, based on dyadic interactions  Xl  (for period June 1 - December 31, 1977)  -  Prop, of  Animal I d e n t i f i c a t i o n Codes  opponents Dominance dominated Value =  WWW  W  RWB  WW  BIBI  *+(2)  (0)  (0)  (0)  + (3)  (0)  RB  BW  W/B  NCT  PBC  (0) + (2)  + (2)  R/B  RBR  W/R  WWW  2  W  3  RWB  (0)  4  WW  (0)  (0) + (2)  5  BIBI  (0)  (0) -(1)  6  RB  (0)  -(3) -(1)  7  BW  -(1)  -(1)  (0) -(2)  8  W/B  (0)  -(1)  (0) -(1)  9  NCT  -(2)  10  PBC  -(2)  -(1)  (0) -(1)  -(2) + (2) -(2) -(5)  11  R/B  -(1)  -(3)  (0) -(1)  -(1) -(1)  12  RBR  13  W/R  -(1)  -(1) -(2) -(1)  (0)  (0)  (0)  (0) -(2)  -(1) -(1)  -(1)  14  NCA  -(1)  -(1) -(1) -(3)  (0)  (0) -(1)  (0) -(2)  -(1) -(1)  -(2) \u00B1(2)  15  WBW  (0)  -(1) -(2) -(1)  (0) -(3) -(1)  (0) -(1)  -(3) -(2)  -(2) -(3)  **\u00B1(2)  + (1) + (3)  (0) + (2) + (1)  (0)  -(1)  + (D (0)  (0) -(4) -(1)  + -(1) E (4) -(1)  + (D+ (D (0) + (D+ (D (0) (0) + (4) (0) + (3)  (0)  -(1)  + (D -(1)  (0) -(2)  + (1) + (1)  (0) + (1) + (3) + (1)  0.83  65.9  (0)  (0)  (0)  (0)  0.67  54.7  + (2)  (0)  (0) + (3)  0.63  52.2  + (D+ (D  0.50  45.0  0.50  45.0  0.43  40.9  0.41  39.8  0.40  39.2  (0)  0.36  36.9  + (2) + (2)  0.15  22.8  + (3)  0.14  21.7  + (D  + (D  + (2)  + (D  (0)  (0)  + (2)  (0)  (0)  (0)  (0)  + (5)  (0)  + (2)  (0)  (0)  (0) -(1)  (0) (0)  (0) -(2)  (0)  (0)  + (D (0)  90.0 65.9  (0)  (0)  (0)  (0)  1.00 0.83  (0)  (0) + (2)  (0)  ARCSIN v^i\"  70.3  + (2) + (1)  (0)  i  0.89  (0)  (0) + (2)  by  + (1) + (1)' + (1) + (2) + (2)  -$(4)  + (D (0)  (0)  WBW  + (D + (D+ (D+ (D (0)  1  (0) + (1)  NCA  (0) -(1)  L i n e a r i t y of hierarchy, based on Landau's Index:  + (D  (0)  (0)  + (D + (D+ (1) + (D+ (3) -(1) + (D+ (1) + (2) (0) + (2) + (2)  + (1) + (2)  (0) -(2) -(3)  0.00  0.0  0.59  *When reading across Tables I and I I , plus signs indicate dominance, minus signs subordination. When reading down, reverse i s true. The number of interaction between each pair of ewes i s given i n parentheses. **+ indicates dominance reversal i n successive i n t e r a c t i o n s .  \u000CTable I I .  Dominance Values o f c a p t i v e ewes, based on d y a d i c  interactions  ( f o r p e r i o d January 1 - June 3 0 , 1978) Prop,  i  R/B  W  WW  RWB  NCT  RB  RBR  W/R  (0)  + (1)  + (5)  + (1)  (0)  + (3)  + (2)  + (4)  -(4)  + (2) + (5)  dominated  Value =  by  ARCSIN  + (1)  + (1)  + (D  1.00  90.0  (0)  + (4)  (0)  (0)  0.90  71.6  + (1)  + (1)  + (5)  + (2)  (0)  0.79  62.4  + (2)  + (3)  + (3)  + (2)  0.78  61.9  + (D  + (2)  + (D  + (D + (D  + (1)  0.56  48.2  + (2)  0.39  38.6  + (1)  0.33  35.3  + (3)  0.21  27.6  + (D  0.14  22.2  0.00  0.0  2  W  (0)  3  WW  (0)  4  RWB  -(1)  -(3)  + (4)  5  NCT  -(5)  -(2)  -(2)  -(5)  6  RB  -(1)  -(4)  -(1)  -(2)  -(1)  7  RBR  (0)  (0)  -(1)  -(3)  -(2)  -(2)  8  W/R  -(1)  -(4)  -(5)  -(1)  -(2)  1(2)  (0)  9  NCA  -(1)  (0)  -(2)  -(3)  -(1)  -(1)  -(1)  (0)  10  WBW  -(1)  (0)  (0)  -(2)  -(1)  -(2)  -(1)  -(3)  + (2)  Dominance  WBW  R/B  **+(2)  opponents NCA  1  *(0)  of  L i n e a r i t y o f h i e r a r c h y , based on Landou's  + (2)  + (2)  t(2) (0)  Index:  + (1) (0) -(1)  1  0.46  *When r e a d i n g a c r o s s Tables I and I I , p l u s s i g n s i n d i c a t e dominance, minus s i g n s s u b o r d i n a t i o n . When r e a d i n g down, r e v e r s e i s t r u e . The number o f i n t e r a c t i o n between each p a i r o f ewes i s g i v e n in parentheses. **+ i n d i c a t e s dominance r e v e r s a l  in successive  interactions.  \u000Csubordinate to the m a j o r i t y (22.8 t o 0 . 0 ) .  The  of  remaining  herd members and had r e l a t i v e l y animals  of  intermediate  status  small were  values dominant  o v e r a p p r o x i m a t e l y t h e same number o f a n i m a l s as t h e y were s u b o r d i n a t e t o .  As  a r e s u l t , Dominance Values f o r t h e s e a n i m a l s c l u s t e r e d around t h e m i d - p o i n t  of  45.0,  r a n g i n g from 36.9 t o  period  (Table  different  II),  the  composition.  54.7.  three  For  groups  Four dominant  the  January  were  again  and  animals  low  (NCT,  mortalities,  (27.6 RB,  to  0.0)  RBR),  Dominance  greatly  Values in  Although  Values,  the  and 0 . 4 6 ,  the  animals  hierarchies  could  be  showed poor  respectively  for  the  linear  that  (Wilson  1975).  It  would  appear  r e s u l t e d from t h e l a c k o f i n t e r a c t i o n s  respectively. numbers  Intermediate  because  of  dominance  ranked  of  linearly  linearity,  generally  winter  S t a b i l i t y o f t h e a d u l t ewes' s o c i a l  s t a b i l i t y of the herd's s o c i a l Winter m o r t a l i t i e s  from on  the  low  index  be  values  the this  their  Landau's A  strongly largely  between many p a i r s o f herd members and  reversals.  o f herd i n t e r a c t i o n s  based  judged t o  There were  no e s t a b l i s h e d  c i r c l e s evident in e i t h e r hierarchy to contribute to t h e i r  The a n a l y s i s  subordinate  1977 and 1978 h i e r a r c h i e s ) .  is  abundance  slightly  l i n e a r h i e r a r c h y would develop w i t h i n  h i e r a r c h y w i t h a s c o r e o f 0.9 o r g r e a t e r  the  of  However, f i n d i n g s p r e s e n t e d below f o r c e d t h e r e j e c t i o n o f  hypothesis.  (0.59  but  sampling  had v a l u e s r a n g i n g from 35.3 t o o n l y 4 8 . 2 .  captive herd.  index  evident  1978,  d e f i n a b l e from t h e i r h i g h (61.9 t o  reduced  I t was h y p o t h e s i z e d t h a t a s t r o n g l y  Dominance  June,  (R/B, W, WW, RWB) and t h r e e  a n i m a l s (W/R, NCA, WBW) were a g a i n c l e a r l y 90.0)  to  dominance  non-linearity.  system  f o r two d i f f e r e n t  time periods  enabled t h e  system t o be e v a l u a t e d o v e r a one y e a r p e r i o d .  r e s u l t e d i n t h e l o s s o f f i v e a d u l t ewes from t h e herd (one  25  \u000Cdominant animals after  -  WWW; f o u r  retained  this  90.0),  relatively  reduction,  intermediate  intermediates  status  constant  positions  with  (D.V.  = 39.1)  dominance was f i r s t  W/B,  Dominance  t o a very  dominance  i n May and J u n e . RB  PBC,  BLBL, Values  within  the  high  first  BW). and  some rank changes were e v i d e n t .  r e v e a l i n g her i n c r e a s e d  more c o n c l u s i v e l y  -  Although social  positions  R/B moved from a low  ranking position  in  late  April,  (D.V.  1978 and then  NCT made a more moderate c l i m b ,  intermediate  social  noted i n mid-May, 1978.  most  class.  reversing  Her  increased  RB showed a c o n s i d e r a b l e  decrease  i n her Dominance V a l u e , d r o p p i n g from 52.2 i n 1977 t o 38.3 i n 1978.  In  July,  enclosure  1977,  a  ewe  from  the  and j o i n e d t h e c a p t i v e  Game herd.  i n c r e a s e i n t h e number o f a g g r e s s i v e disrupt  the  established  Farm  paddocks  This  occurrence  interactions  hierarchy.  The  ewe  dominant a n i m a l , a l t h o u g h her s t a y was t o o  jumped  into  caused  the no  study  apparent  w i t h i n t h e herd nor d i d  appeared  limited  to  to  be  a  accurately  it  relatively assess  her  status.  2.  Determinants o f dominance  The p r e d i c t e d d e t e r m i n a n t s not  clearly  related  to  o f dominance social  status  (age, in  demonstrate t h a t t h e t h r e e most s u b o r d i n a t e youngest  adults  (three years  ewe was  one  the  of  four  o f age)  most  horn l e n g t h , body w e i g h t ) the  herd.  ewes  in  i n the herd.  dominant  ewes  in  Age  estimates  each h i e r a r c h y  correlated to social  the  However, a f o u r y e a r  old  each  ewes.  26  rank  did  were  hierarchy.  Since  e s t i m a t e s by horn a n n u l i were o n l y c o n s i d e r e d a c c u r a t e up t o s i x y e a r s , c o u l d not be m e a n i n g f u l l y  were  for  the majority  of  age ages the  \u000CT a b l e I I I C o r r e l a t i o n between Dominance V a l u e s ( D . V . ) and p r e d i c t e d d e t e r m i n a n t s o f dominance: a g e ( A . ) , body weight (WT.), horn l e n g t h ( H . L . ) and a g g r e s s i v e n e s s (AG.) ( i . e . number o f i n t e r a c t i o n s i n i t i a t e d ) June t o December, 1977 Social Class  Animal I.D.  Dominants  Mean 1977 Weight (kg)  Mean 1977 Horn Length (mm)  D.V.  Age  WWW  90.00  6+  50.5  302.5  9  w  70.3  6+  50.5  275.0  15  RWB  65.9  4  56.5  271.0  11  WW  65.9  6+  60.5  277.5  8  Inter-  BIBI  54.7  6+  46.5  280.0  3  mediates  RB  52.2  6+  53.0  270.0  9  BW  45.0  6+  52.5  280.0  3  W/B  45.0  6+  50.0  305.0  6  NCT  40.9  6+  50.5  264.5  4  PBC  39.8  6+  49.5  230.0  6  R/B  39.2  6+  55.0  262.0  4  RBR  36.9  6+  56.5  287.5  4  Sub-  W/R  22.8  3  52.0  244.5  2  ordinates  NCA  21.7  3  52.0  230.0  4  WBW  0.0  3  44.5  253.0  0  Correlation coefficients:  r/\\  #  r  r  r  WT. H.L. AG.  Aggressiveness  not o b t a i n a b l e w i t h a g i n g t e c h n i q u e s used =  0.33  =  0.61 (p &lt; 0.05)  =  0.79 (p &lt; 0.05)  27  (NS)  \u000CT a b l e IV  C o r r e l a t i o n between Dominance V a l u e s ( D . V . ) and p o s s i b l e o f dominance  determinants  January t o J u n e , 1978 Social Class  Animal I.D.  Mean 1978 Horn Length (mm)  Aggressiveness)  Dominants  55.0  261.5  10  6+  51.0  277.0  13  62.4  6+  55.0  280.5  12  RWB  61.9  5  57.0  271.0  17  Inter-  NCT  48.2  6+  51.0  269.5  7  mediates  RB  38.6  6+  51.5  270.0  5  RBR  35.3  6+  55.0  291.0  1  Sub-  W/R  27.6  4  50.5  250.0  4  ordinates  NCA  22.2  4  52.5  233.0  0  WBW  0.0  4  45.0  261.0  0  D.V.  Age  R/B  90.00  6+  W  71.6  WW  Correlation coefficients:  Mean 1978 Weight (kg)  TA. WT. r .  r  u  r  A G &lt;  =  not o b t a i n a b l e w i t h a g i n g t e c h n i q u e s used  \u00B0(P = 0.36  =  =  6 7  &lt;  \u00B0- ) 0 5  0.81 (p &lt; 0.05)  28  \u000CIn 1977, w e i g h t s and Dominance Values were p o o r l y significantly  correlated  in  1978  (r  = 0.55;  correlated  p &lt; 0.05)  (r  (Tables  = 0.33) III  The r e v e r s e was t r u e f o r horn l e n g t h s , w i t h t h e horn l e n g t h - D.V. coefficients in  1977  and  1978  being  0.61  (p  &lt; 0.05)  and  but  and  IV).  correlation  0.35  (not  sig.),  respectively.  Although  no m o r p h o l o g i c a l  criteria  were s t r o n g l y  both 1977 and 1978, a g g r e s s i v e n e s s requirement aggressive  for  high  social  interactions  correlation  to  Dominance  to  dominance  appeared t o be a c o n s i s t e n t l y  status.  initiated  correlated  In  both  hierarchies,  by an i n d i v i d u a l  Value  ( igjj  \u00B0- 76;  =  r  showed  significant  the  number  a high,  r^gyg  =  in  of  positive  0.81;  p  &lt;  than  a  0.05).  Alternatively,  aggressiveness  may  determinant  dominance,  dominance  of  o t h e r , more s u b t l e  and  have  been may  were s t r o n g d e t e r m i n a n t s o f s o c i a l  have  been  rather  attributed  to  some  age, horn l e n g t h and body weight  s t a t u s had t o be r e j e c t e d .  Consequences o f Dominance  1.  It  result,  factor(s).  Based on t h e s e r e s u l t s , t h e h y p o t h e s i s t h a t  B.  a  was  Diet  predicted  comparisons  that  dominant  animals  would,  during  a v a i l a b l e f o r a g e , have g r e a t e r a c c e s s t o h i g h q u a l i t y  months  of  f e e d i n g s i t e s and would  remain on a h i g h e r p l a n e o f n u t r i t i o n than more s u b o r d i n a t e a n i m a l s . results  of  the  diet  comparisons  conducted  29  between  limited  social  groups  However, forced  the  \u000Crejection  of  this  supplemental  hypothesis.  feed  in  Neither  January  (Table  the  Va),  times  nor  the  spent fecal  at  high  N levels  December, 1977 and March, 1978 samples ( T a b l e Vb) were s i g n i f i c a n t l y between s o c i a l  2.  The  that  dominant  shortages in high q u a l i t y social  classes  animals  would  show  shorter  f o r a g e was a l s o r e j e c t e d .  did  (September t o M a r c h ) .  not  differ  in  Some d i f f e r e n c e s  In O c t o b e r ,  was  that  statistically  Intermediate  similar  to  ewes, however,  of  the  grazing  used  for  times  Intermediates  bedded s i g n i f i c a n t l y  less  others w h i l e ,  class.  the  October,  and  between  This  Intermediates  was  differences  the  activity  particularly  were budgets  true  for  Dominants  Subordinates.  than S u b o r d i n a t e s . to that  bedded s i g n i f i c a n t l y  minimal, of  there  In  of  longer  animals  ewes  of  were  within  the than  statistical  model  in  all  months  and s i g n i f i c a n t l y  variable  Subordinate animals d i f f e r e d l i t t l e  tested  considerable  a  intermediate  g r a z i n g o r bedding t i m e s c o n t r i b u t e d s i g n i f i c a n t l y  Dominant a n i m a l s showed s i g n i f i c a n t l y February  although  (see T a b l e V I ) .  between-class  dissimilar of  unlike  the  comparisons  t h e mean bedding t i m e o f  both  and  months o f  i n bedding t i m e s ,  J a n u a r y , t h e mean bedding time o f Dominants was a g a i n s i m i l a r  differences  different  The g r a z i n g t i m e s o f  months  did arise  not i n t h e manner p r e d i c t e d .  Although  in  A c t i v i t y budget comparisons  l o n g e r bedding t i m e s than more s u b o r d i n a t e a n i m a l s d u r i n g p o t e n t i a l  Subordinates  found  groups.  hypothesis  three  quality,  except  given  social  status  whose  to the  February  variance  and  March.  v a r i a b l e bedding t i m e s i n September and grazing times  in  November  in their a c t i v i t y  patterns,  o n l y v a r i a b l e g r a z i n g t i m e s i n November and F e b r u a r y .  30  and  February.  demonstrating  \u000CTABLE V  a)  b)  D i e t comparisons between Dominants, I n t e r m e d i a t e s and Subordinates  Average d a i l y hours spent a t supplemental  feed - January,  Social Class  Mean hours  Dominants  1.65  (S.D.I = l.20)  Intermediates  1.85  (S.D.  = 1.68)  Subordinates  1.28 ( S . D .  = 1.11)  1978.  feeding  Fecal N l e v e l s - December, 1977 and March, 1978 No. o f December Samples  Average % Fecal N  No. o f March Samples  Average % Fecal N  8  1.60 (S.D.=0.21)  5  1.77 (S.D.=0.12)  Intermediates  10  1.76 (S.D.=0.39)  3  1.62 (S.D.=0.06)  Subordinates  14  1.64 (S.D.=0.11)  5  1.63 (S.D.=0.08)  Social  Class  Dominants  IS.D. = standard d e v i a t i o n  31  \u000CTable V I .  Average daylight feeding and bedding times f o r Dominants, Intermediates and Subordinates (September 1977 to March 1978).  Month Sept.  Oct.  Social  Feed.  Class  (hrs) (hrs)  Dominants  Intermediates  Subordinates  9.26  Bed.  1.85  Nov.  Bed.  (hrs) (hrs) 7.93 (0.78)  9.26 1.83 (1.43) (0.98)  8.11 1.24a (1.09) (0.67)  9.07  1.92  7.93  Feed.  Dec.  Bed.  (hrs) (hrs)  1.45ab2 7.69  (1.53)1 (0.96)  (1.20) (0.66)  1  Feed.  0.64  (0.69) (0.72) (0.53)  1.64b  (0.92) (0.64)  7.68 0.29 (0.96) (0.75) 7.55  0.87  (0.68) (0.59)  Feed.  Jan.  Bed.  (hrs) (hrs) 5.48  1.40  (1.27) (1.15) 5.25 1.85 (1.46) (1.40) 5.29  1.37  (1.49) (1.11)  Feed.  Feb.  Bed.  (hrs) (hrs) 5.27  2.14ab  (1.16) (0.92) 5.0 2.58a (1.62) (1.24) 5.61  1.78b  (0.90)  (0.82)  Feed.  Mar.  Bed.  (hrs) (hrs) 7.34  1.43  (1.74) (1.06) 7.02 1.37 (1.53) (0.65) 7.00  1.65  (1.62) (1.07)  values i n parenthesis are standard deviations  2 within a given column, values with different small case letters are s i g n i f i c a n t l y different (p &lt; 0.05)  Feed. Bed. (hrs) 8.52  (hrs) 1.81  (0.89) (1.24) 8.25 2.42 (0.85) (0.86) 8.15  2.17  (0.61)  (0.89)  \u000C3.  All  Productivity  hypotheses o f t h i s  study p r e d i c t i n g t h e improved p r o d u c t i v i t y o f dominant  a n i m a l s were r e j e c t e d . did  not  differ  comparisons  Seasonal  significantly.  showed a w e i g h t  loss  weights  (Table  VII).  average  weight  gain  (32.5%  vs.  18.6%  of  between f i v e  from  March 17.3%  to of  all  of  animals loss  autopsied in d e t a i l ,  of  August March  premolars  i n the three December,  their  appeared  to  demonstrate  than body  Dominants weights  and  classes  all  of  classes  October  body higher  Intermediates  respectively),  1977-78 w i n t e r .  Without  emaciated.  showed advanced s t a g e s  and m o l a r s .  1977,  percent  o f age and s e v e r e l y  all  social  the  significant.  f i v e animals died during the  a n i m a l s were over s i x y e a r s  to  and s i x  Subordinates  d i f f e r e n c e s were not s t a t i s t i c a l l y  A total  changes  From October  Although  and  weight  Although  four  of  the  of five  exception, Of t h e  four  gum n e c r o s i s deaths  and  occurred  w i t h i n t h e i n t e r m e d i a t e s o c i a l c l a s s , t h e f r e q u e n c y o f death w i t h i n each c l a s s d i d not vary s i g n i f i c a n t l y  from e x p e c t e d v a l u e s . ( C h i ? = 1.70, d f = 2 ) .  The hypotheses t h a t dominant ewes would be r e p r o d u c t i v e l y more s u c c e s s f u l ewes o f 1978.  lower  social  rank  was  rejected  on t h e  basis  of  lamb  than  production  Of t h e t e n r e m a i n i n g a d u l t ewes c o m p r i s i n g t h e herd i n 1978, f o u r were  c o n s i d e r e d Dominant, t h r e e I n t e r m e d i a t e , and t h r e e S u b o r d i n a t e i n s t a t u s . these  in  ewes,  three  Dominants,  one  Intermediate  and  l a m b s , w i t h one lamb o f t h e dominant group d y i n g a t While these f i g u r e s  one  Subordinate  or s h o r t l y  g i v e t h e i m p r e s s i o n o f a preponderance o f  after  produced birth.  reproductively  s u c c e s s f u l dominant ewes, t h e frequency o f lambs from each group d i d not significantly  from e x p e c t e d v a l u e s (Chi2 = 0 . 8 4 , df = 2 ) .  33  Of  vary  \u000CTABLE V I I Seasonal w e i g h t change comparisons o f Dominants, I n t e r m e d i a t e s , and S u b o r d i n a t e s  Social  Class  Average weight l o s s O c t - D e c , 1977 (% o f O c t . body w t . )  Average weight g a i n March-Aug, 1978 (% o f March w t . )  Domi nants  5.27 ( S . D . I = 3.04)  18.57 ( S . D . = 2.93)  Intermediates  5.04 ( S . D . = 3.31)  17.27 ( S . D . = 8.3)  Subordinates  5.63 ( S . D . = 4.63)  32.50 ( S . D . = 19.16)  1 S.D. = s t a n d a r d d e v i a t i o n  34  \u000CForage A v a i l a b i l i t y and Herd B e h a v i o u r  c. Ninety  plant  s p e c i e s were  1977 s a m p l i n g p e r i o d the area  is  identified  (Wikeem &amp; P i t t  dominated  the  pers.  by a bluebunch  sage (Artemi s i a t r i d e n t a t a ) of  i n the  ground c o v e r .  study  site  comm.).  wheatgrass  enclosure  As p r e v i o u s l y (Agropyron  during  the  described,  spicatum)  -  big  community w i t h g r a s s e s c o n t r i b u t i n g more than 40%  Table V I I I  lists  the  mean c o v e r  values  of  the  major  u n d e r s t o r y p l a n t s p e c i e s determined from 1977 d a t a (from Wikeem, unpub. d a t a ) . I t s h o u l d be emphasized t h a t t h e s e a r e mean v a l u e s significantly forbs,  for  f o r t h e y e a r and may vary  from e s t i m a t e s determined a t any p a r t i c u l a r p o i n t i n t i m e . example,  are  senescent  for  much  of  the  year,  but  Many  contribute  s i g n i f i c a n t l y t o t h e ground c o v e r d u r i n g t h e s p r i n g growing s e a s o n .  Of t h e 90 p l a n t s p e c i e s p r e s e n t ,  67 were u t i l i z e d by t h e sheep a t some p e r i o d  throughout  various  degrees  of  always  similar  to the  botanical  a  degree  of  the year  at  Diet  c o m p o s i t i o n was not  area  as  the  particular  sheep  plant  demonstrated  species  high  but f o r p l a n t  intensity  parts  (Wikeem,  pers.  composition  selectivity  as w e l l  comm.).  (Pitt  not  of  the  only  for  and Wikeem 1979,  Wikeem, p e r s . comm.).  The  seasonal  the  study  p r o d u c t i o n o f new growth by s e v e r a l  plant  species,  growth  Agropyron  secunda were i n f i r s t  cycle  for  spicatum,  Bromus  area  commenced  species.  tectorum,  in  March  the  Of t h e more common g r a s s Koeleria  cristata  o r second l e a f s t a g e s w i t h a t l e a s t 3 cm o f  35  with  and  Poa  \u000CTable VIII  Mean c o v e r o f t h e major u n d e r s t o r y p l a n t s p e c i e s over t h e 1977 sampling p e r i o d (From Wikeem, i n p r e p . )  Plant Species  % Cover  ( s p e c i e s names from H i t c h c o c k and C r o n q u i s t  1973)  Grasses Agropyron s p i c a t u m  20.53  Bromus t e c t o r u m  10.24  Koeleria cristata  3.63  S t i p a comata  3.32  Poa secunda  2.79  Festuca s c a b r e l l a  trace  Forbs Balsamorhiza s a g i t t a t a  2.16  Eriogonum niveum  1.36  Eriogonum h e r a c l e o i d e s  0.94  Achillea millefolium  0.89  A n t e n n a r i a dimorpha  0.34  Antennaria p a r v i f l o r a  0.26  Lupinus s e r i c e u s  0.24  C a s t i l l e j a thompsonii  0.22  Artemisia tridentata  8.07  Symphoricarpos a l b u s  0.65  Chrysothamnus nauseosus  0.57  Shrubs  Others  ( g r a s s e s , f o r b s , shrubs)  5.89  Total cover  62.36  S o i l and rock  17.64  Litter  17.18 97.18  36  \u000Cvisible  growth by m i d - M a r c h .  Balsamorhiza browse  sagittata  and A c h i l l e a  preference  towards  the new  time  of  growth  this  by  and  on  period  at  alnifolia  bursting  A l t h o u g h e s t i m a t e s o f d i e t c o m p o s i t i o n had not been completed f o r t h i s growth  Amelanchier  buds were  as  al bus  initial  including  millefolium while  on such f o r b s  Symphoricarpos  of  species  New l e a v e s were a l s o e v i d e n t  study's  the  completion,  sheep  was  a  obvious  progressive from  ocular  r e c o n n a i s s a n c e o f t h e a r e a ' s v e g e t a t i o n (Wikeem, p e r s . comm.).  From  late  May  vegetative species  to  late  biomass  passing  for  July,  1977,  and  selectivity,  through  their  sericeus)  nutritious generally  and shrubs  common g r a s s e s  study  area  the year with the m a j o r i t y rapid  flowering or f r u i t i n g stages. palatable  the  growth  supported  of  phase  and  With t h e a v a i l a b i l i t y  plants,  the  preferring  (Amelanchier  sheep  forbs  grass,  greatest  forb  and  progressing  shrub  into  the  o f a wide range o f  demonstrated  (Balsamorhiza  alnifolia)  its  a  degree  sagittata,  and s e l e c t i n g  (Bromus t e c t o r u m , Agropyron s p i c a t u m )  high  very  against  Lupinus the  more  ( P i t t and Wikeem, 1 9 7 9 ) .  From mid-June t o mid-September, t h e study s i t e e x p e r i e n c e d t h e s e a s o n a l l y temperatures plant  and dry  species  Koeleria cristata Achi11ea  foraging  common t o  had c u r e d by l a t e A u g u s t .  f o l i a g e were s t i l l  and  conditions  Although  nauseosus  most  With  forbs  the  which  dried  exception  showed  only  A u g u s t , t h e common shrubs on t h e study s i t e  development.  had  formed  and  dropped  their  and of  and t h e  limited  majority  amounts o f  Eriogonum  withered Artemisia  initial  of  green  heracleoides  into  an  and  unusable  tridentata  flower  offered  and  development  (Symphoricarpos a l b u s , fruit  high  as Agropyron spicatum and  and such f o r b s as Eriogonum niveum,  condition.  alnifolia)  region  observed i n such common g r a s s e s  millefolium,  Chrysothamnus  this  of  no  in  Amelanchier new  leaf  With t h e d e c l i n i n g a v a i l a b i l i t y o f f o r b s and s h r u b s , t h e sheep  37  \u000Cexerted  greater  selectivity  foraging  for  pressure  particular  species  on  the  but  common  being  grasses,  highly  showing  selective  for  r e m a i n i n g green growth o f F e s t u c a s c a b r e l l a , Agropyron s p i c a t u m and cristata,  From  i n t h a t o r d e r (Wikeem, p e r s . comm.; p e r s .  mid-September  major p e r e n n i a l  to  mid-November  some  and r e m a i n i n g f o r b s . although Artemisia  any  Koeleria  observations).  regrowth  bunch g r a s s e s , annual g r a s s e s  less  occurred  for  all  of  the  (Bromus t e c t o r u m , Bromis  mollis)  By l a t e O c t o b e r , most shrubs had dropped t h e i r  leaves,  tridentata  and Chrysothamnus  f l o w e r i n g o r seed p r o d u c t i o n s t a g e .  During t h i s  nauseosus were  still  in  the  p e r i o d , t h e regrowth o f  the  g r a s s s p e c i e s formed t h e bulk o f t h e s h e e p ' s d i e t , a l t h o u g h use o f some f o r b s (Eriogonum niveum, JE. h e r a c l e o i d e s ) a l s o c o n t i n u e d (Wikeem, p e r s . comm.).  From  December  apparent  and  to  February,  the  botanical  no  significant  composition  of  growth the  in  study  the area  vegetation changed  was  little.  Green f o l i a g e was p r e s e n t throughout t h i s p e r i o d on many o f t h e common g r a s s e s and f o r b s but was not r e a d i l y snow c o v e r  by  late  December.  a v a i l a b l e once t h e a r e a r e c e i v e d a 15 t o 30 cm. The  animals  exerted  their  p r e s s u r e on Agropyron s p i c a t u m and K o e l e r i a  cristata,  recent  but u t i l i z i n g  growth o f  vegetation Artemisia until  during  the the  tridentata,  s p r i n g growth o f  plants deep A.  where p o s s i b l e snow  frigida).  (&gt; 20 This  cm)  period  diet  greatest  c r a t e r i n g f o r t h e most primarily  (e.g.  remained  E_.  t i m e , the sheep were h i g h l y s e l e c t i v e f o r t h i s new growth.  emergent  heracleoides,  relatively  g r a s s e s and f o r b s commenced i n e a r l y March.  38  foraging  constant At  that  \u000C1.  Seasonal d i u r n a l  Monthly a c t i v i t y diurnal  graphs  pattern.  representative  patterns  ( F i g . 1) demonstrate t h e seasonal  Each  for  graph  that  contains  month.  demonstrate t h e e f f e c t s  Two  of winter  The average number o f d a i l y  data days  storms  activity  from are  one  c y c l e of the  day  presented  and snow c o v e r  herd's  considered for  to  be  December  to  on herd  behaviour.  peaks observed i n each month appears on  the appropriate graph.  In May and J u n e , t h e herd members f o l l o w e d a c y c l i c a l w i t h moderate d a i l y dawn,  mid-morning  active  period  approximately would during  variations. (8:00  -  the  most  16:00  hrs  to  occasionally  prompt  May, w e a t h e r ,  in  In g e n e r a l , major a c t i v i t y  10:00  was  hrs),  noon and  extensive,  after a  dark.  brief,  general,  late  stretching Although  unscheduled  had l i t t l e  onset, duration or p e r i o d i c i t y of a c t i v i t y  In J u n e , a f i f t h  and synchronous  peaks o c c u r r e d a t  afternoon. over  four  short-lived  bedding  visible  The  final  hours  from  cloud  period  effect  pattern  by  on t h e  bursts  the  herd  time  of  peaks.  peak o f s h o r t d u r a t i o n o f t e n o c c u r r e d a t a p p r o x i m a t e l y  14:00  h r s and t h e l a t e a f t e r n o o n p e r i o d was b i s e c t e d by a s h o r t bedding s e s s i o n .  As  a r e s u l t , a d a i l y average o f 5.3 a c t i v i t y peaks was observed i n J u n e , compared t o o n l y 4 . 3 i n May.  In J u l y , diurnal  an average patterns  of  5.0  peaks o c c u r r e d each d a y ,  was g r e a t e r than  the  previous  were c o n s i s t e n t l y  observed a t dawn and from l a t e  peaks  interim  during  distributions  the  daylight  hours  from day t o day.  39  showed  but d a i l y  two months.  variation  Active  e v e n i n g t o dusk. a  variety  of  in  periods However,  durations  and  \u000CFIGURE 1  Graphs o f monthly d i u r n a l (May 1977 t o A p r i l  T  =  p a t t e r n s o f t h e c a p t i v e herd  1978)  mean t e m p e r a t u r e (\u00B0C) f o r t h a t s a m p l i n g d a y . given i n  Range o f temperatures  are  brackets  x  =  mean number o f d a i l y a c t i v i t y peaks demonstrated f o r t h a t month.  S  =  range o f snow a c c u m u l a t i o n on t h e study  y  =  percent of the t o t a l  site.  herd a c t i v e a t each 15 minute  PST = P a c i f i c Standard Time, i n h o u r s . No. o f s a m p l i n g days/month:  3 (Jan., Apr.) 4 ( J u l y , Aug., Dec., Mar.) 5 (Sept.,  Feb.)  6 (June, O c t . ) 7 (May, Nov.)  sampling  interval  \u000C1004  1  27 May  \u00A7  T=15.1\u00B0  I  U=4.3so.6  (7.8-22.2)  3June  HI '  1  I T=17.7\u00B0 |  (10.0-25.4)  1  X=5.3so.6  UJ &gt;  o &lt; z  UJ  O  CC UJ  0.  23 September  1=12.6\u00B0 (9.5-15.5) X= 1.3*0.0  4  5  6  7  8  9  10  11  12  13  14  15 16  TlME[hours-PST]  41  17  18  19 2 0  21  \u000C\"i\u2014I  1  1  1  1  1  1  1  1  r\u2014r\u2014i  1  1  r  5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22  TIME  42  \u000C5  6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 TIME  43  \u000CAugust data were t h e f i r s t t o show a breakdown i n t h e c y c l i c a l previously  observed.  only  evening  were  slightly again  more than  always  Weather d u r i n g much o f Consequently,  pattern  An average o f 4.5 peaks o c c u r r e d each day but many o f  t h o s e observed from mid-morning t o m i d - a f t e r n o o n were o f involved  diurnal  present  June,  no r e l a t i o n s h i p  r e c o g n i z e d on a d a i l y  50% o f  July  but  the  herd.  varied  Peaks  in  and August was  short  length  durations  at  dawn and  from  consistently  between weather and d i u r n a l  day hot  patterns  for  period distinct  much o f  day.  and  dry.  could  day.  demonstrated  bedding s e s s i o n two d i s t i n c t  by  daylight  apparent hours.  September,  herd  dropped  and, to  there  was  resultantly,  1.3  per  day.  no c o n s i s t e n t the In  average  active  that The  t h r o u g h o u t t h e day.  some a n i m a l s average  were  number  active  of  peaks  For t h e  bedding  an  obvious  first  into  inactive time,  continuously  throughout  observed  day  per  of  period  November d a t a , however, showed a reduced midday levels  given  number  October,  r e t u r n e d a t midday, d i v i d i n g t h e d a y l i g h t  p e r i o d and h i g h a c t i v i t y became  In  the  peaks  peaks.  be  basis.  the  activity  late  to  From September t o November, t h e m a j o r i t y o f t h e herd was a c t i v e a t any time  and  was  it the  1.67.  A l t h o u g h , w i t h i n each month, weather was v a r i a b l e , t h e r e was a g a i n no obvious r e l a t i o n s h i p between weather and t h e a n i m a l s '  diurnal  In December, t h e herd demonstrated two e n t i r e l y d i f f e r e n t t i m e s o f t h e month.  The f i r s t  pattern.  different  diurnal  patterns  f o u r days o f December were  relatively  m i l d (above f r e e z i n g ) w i t h o n l y t r a c e a c c u m u l a t i o n s o f snow on t h e study From December 12 t o 3 1 , ground a c c u m u l a t i o n s  at  o f snow were a g a i n minimal  site. with  mean d a i l y t e m p e r a t u r e s d i p p i n g s l i g h t l y below f r e e z i n g o n l y i n l a t e December. In  the  interim  period,  t e m p e r a t u r e s and a 15 t o  however,  the  20 cm snow c o v e r .  44  study  site  experienced  The herd r e a c t e d t o each  sub-zero ambient  \u000Ccondition  in a different  herd a c t i v i t y  patterns  manner.  During the mild and/or  resembled t h o s e o f  herd b e i n g a c t i v e t h r o u g h o u t t h e day.  snow-free  periods,  November, w i t h t h e m a j o r i t y  of  the  The midday bedding p e r i o d was even l e s s  e x t e n s i v e than November.  D u r i n g t h e seven days o f snow a c c u m u l a t i o n s and c o l d  temperatures,  and  midday For  a  bedding  the  first  activity  in  morning period  time  the  afternoon  involving  in  the  early  almost  study,  morning  activity the  the  and  entire  animals  late  peak  were  herd  showed  evening  present,  separating  with the  significantly  hours.  For  a  two.  reduced  December,  an  average o f 1.3 a c t i v i t y peaks were observed per day.  In J a n u a r y , study  site  a crusted  snow c o v e r o f  and s l i g h t l y  northeast  30 cm on h i g h e r  sub-zero temperatures  p r e s e n t f o r much o f t h e month. supplemental  up t o  As p r e v i o u s l y  (monthly  portions  mean o f  c o r n e r o f t h e study a r e a .  -2.1\u00B0C)  mentioned, a l i m i t e d  f e e d (45 kg o f hay per day) was p r o v i d e d f o r t h i s  of  were  supply  the  In g e n e r a l , t h e herd would feed at  the  d e p l e t i o n , move t o t h e lower  o f t h e e n c l o s u r e t o f o r a g e on t h e n a t i v e  v e g e t a t i o n f o r t h e remainder o f  Early  morning  activity  was  of  period in  hay f o r much o f t h e morning and upon i t s  day.  the  minimal  but  herd  activity  slopes  remained  the high  throughout t h e day once f o r a g i n g was i n i t i a t e d , u s u a l l y by l a t e morning (11:00 hrs).  Data  from  only  one  observation  day  mid-morning f o r a g i n g and a synchronous morning t o dusk a c t i v i t y peak (x = 1.3  In F e b r u a r y ,  snow a c c u m u l a t i o n  was a g a i n  dependent  solely  avoidance  of  morning  early  and t h e herd showed l i t t l e  a  significant  degree  bedding p e r i o d b e f o r e t h e normal  of late  peaks/day).  rapidly  d e c l i n e d on l o w e r s l o p e s and t h e  on t h e mature hours  showed  by  the  difference  in  vegetation animals its  of  the  was  diurnal  no  longer  pattern  The m a j o r i t y o f t h e a n i m a l s began f o r a g i n g a t o r s l i g h t l y  45  study  site.  herd An  pronounced  from  January.  b e f o r e 8:00 hrs and,  \u000Cin  general,  remained  active  throughout  the  day  from t h a t  time  on.  As  in  J a n u a r y , an average o f 1.3 a c t i v i t y peaks per day was o b s e r v e d .  March d a t a showed t h e r e t u r n o f m u l t i p l e a c t i v e and bedding p e r i o d s d u r i n g t h e daylight hours. and  a  second,  Although the second  more  inactive  average  extensive  one  stretched  o n l y major bedding s e s s i o n  participation, The  An a c t i v i t y peak was once a g a i n c o n s i s t e n t l y observed at dawn  period,  varying  was f r e q u e n t l y number  of  in  from  late  o c c u r r e d a t mid t o  duration  and  peaks  observed  late  degree  observed a t mid a f t e r n o o n  activity  morning  herd  (13:00 day  synchronous  and  dusk.  morning,  of  per  to  a  member  15:00 h r s ) .  increased  from  F e b r u a r y ' s v a l u e o f 1.3 t o 2.3 i n March.  In  April,  activity year. one  the  herd members were  patterns,  complete  sampling  varied  inactivity  observations  afternoon  (16:00  daily  in  cyclic  s i m i l a r t o t h a t observed i n May and June o f  The herd would f r e q u e n t l y of  extremely  in  transfer the  interval  (15 m i n . ) .  hrs)  and  between  Consistent  evening  distribution  from an a c t i v e ,  to  dusk  peaks while  and d u r a t i o n .  An  the  foraging  two  their  previous state  consecutive  occurred interim  average  in  at  of  scan  dawn,  activity 5.3  to  late  periods  peaks  were  observed per s a m p l i n g d a y .  Although i n t e n s i v e f i e l d additional 17,  for this  study ended on June 30,  1978,  herd a c t i v i t y d a t a were c o l l e c t e d on November 14, 1978 and December  1978 d u r i n g b r i e f  herd's  observations  diurnal  pattern  visits to  t o the be  study  determined  site after  (Fig. a  1).  growing  This  enabled  season  in  the  which  g r a z i n g p r e s s u r e had been reduced c o n s i d e r a b l y from t h e p r e v i o u s y e a r .  On November 14, weather c o n d i t i o n s  were s e a s o n a l , w i t h  46  clear  skies  and day-  \u000Cl i g h t t e m p e r a t u r e s r a n g i n g from -3\u00B0C t o 0 \u00B0 C . snow t o t h a t d a t e .  Four a c t i v i t y  The study a r e a had not  peaks were o b s e r v e d , t h e two most  o c c u r r i n g from dawn t o e a r l y morning (9:00 h r s ) and from l a t e (18:00 h r s ) t o d u s k . hrs.  This  pattern  received extensive  afternoon  Two a d d i t i o n a l peaks were observed a t 9:45 h r s and 12:30 varied  considerably  from that demonstrated  in  November,  1977, where t h e m a j o r i t y o f t h e herd was a c t i v e a t any g i v e n time f o r most o f the day.  On December 1 3 ,  1978,  a 5 cm snow c o v e r  made ambient c o n d i t i o n s December,  1977.  similar  and s l i g h t l y  to those present  However, t h e h e r d ' s d i u r n a l  pattern  i n t h e e a r l y morning and l a t e e v e n i n g ,  temperatures  d u r i n g t h e stormy  on m i l d e r , s n o w - f r e e days o f t h e p r e v i o u s December. slightly  sub-zero  resembled t h a t  of  observed  A c t i v i t y was reduced o n l y  and t h e m a j o r i t y  was a c t i v e a t any g i v e n t i m e throughout t h e e n t i r e  period  day.  of t h e  herd  Some i n a c t i v i t y  was  o b v i o u s a t midday but i n v o l v e d o n l y 45% o f t h e herd a t i t s peak p e r i o d .  Nocturnal  activity  The degree o f n o c t u r n a l a c t i v i t y o f t h e herd v a r i e d c o n s i d e r a b l y w i t h t h e time of year. hrs  On May 5 and June 20, 1978, t h e herd was observed from dusk t o 24:00  Pacific  Lighting  was  Standard  Time  considered  to  (PST) be  at  under  clear  a minimal  skies  and m o o n l i t  level  (animals  were  conditions. no  longer  v i s i b l e w i t h o u t t h e spot lamp) by 19:30 and 21:15 h r s PST, r e s p e c t i v e l y . both o c c a s i o n s ,  the h e r d s e m e d t o  continue the c y c l i c  On  grazing/bedding  pattern  e s t a b l i s h e d d u r i n g t h e d a y l i g h t hours o f t h e s e months, a l t h o u g h a c t i v e  periods  were l e s s e x t e n s i v e and i n v o l v e d fewer a n i m a l s . bedded by 20:08 h r s ,  approximately  The e n t i r e herd on May 5 was  38 minutes a f t e r  complete d a r k n e s s .  t h e e x c e p t i o n o f minor s h u f f l i n g o f bedding s i t e s , t h e r e was no a c t i v i t y  47  With from  \u000Ct h i s t i m e t o 22:10 h r s , when f o u r a n i m a l s began f o r a g i n g .  A limited  activity  peak i n v o l v i n g o n l y f o u r t o  s i x a n i m a l s at a time c o n t i n u e d f o r t h e remainder  of the observation p e r i o d .  During t h i s  immediate v i c i n i t y bedded  by  21:00  o f t h e bedding a r e a . hrs,  complete d a r k n e s s , time,  a  activity  15 minutes  bout  peak which  was  On June 2 0 , t h e herd was  before  initiated  involved  all  the grazing animals  By 23:19 h r s , a l l  f o r a g i n g was r e s t r i c t e d t o  the  area  and t h e herd remained i n a c t i v e  foraging  observations,  time,  but  by  three  five  was  to  22:35 h r s .  animals,  be At  culminating  herd members.  remained w i t h i n  completely  considered  until  Similar  50 m o f t h e  the  in  that in  to  an  May 5  bedding  area.  a n i m a l s had rebedded and c o n t i n u e d t o do so f o r t h e r e s t  of  the observation p e r i o d .  On November 14, 1978 d u r i n g t h e r u t t i n g  period,  the  herd was monitored  from  dusk t o 21:00 h r s P a c i f i c Standard Time (PST) i n c l e a r m o o n l i t c o n d i t i o n s slightly  sub-zero  temperatures.  observed  at  hrs,  light  levels  17:02 for  the  15 minutes night,  Although before  bedding was  initial  signs  the  area  not  extensive  of  experienced for  when a l l  but seven a n i m a l s bedded.  its  almost  because o f t h e c o n t i n u e d harassment o f ewes by c o u r t i n g rams. 13 o f t h e 26 herd members were s t i l l  bedding  and were  minimum an  hour  By 17:55  hrs,  a c t i v e and remained so u n t i l  18:30  hrs  The e n t i r e herd f i n a l l y became i n a c t i v e  at  19:05 h r s and no f o r a g i n g o r c o u r t s h i p b e h a v i o u r was observed f o r t h e r e s t  of  the monitoring p e r i o d .  At dawn t h e f o l l o w i n g morning, o n l y e i g h t o f t h e herd  members  significant  had  moved  a  i n d i c a t i n g l i m i t e d nocturnal  distance  (&gt;  100  m)  during  the  movement.  On December 17, n i g h t o b s e r v a t i o n s were r e c o r d e d from dusk t o 20:00 h r s a low o v e r c a s t approximately  sky and -3\u00B0C t e m p e r a t u r e s . 15 cm o f  night,  fresh  snow.  The study  Bedding  48  activity  under  a r e a was b l a n k e t e d was  initiated  by  by the  \u000Canimals  at  16:05  hrs,  approximately  40  minutes  before  total  darkness  p r o g r e s s e d g r a d u a l l y u n t i l t h e e n t i r e herd was bedded by 17:45 h r s . exception of occasional  shifts  i n bedding s i t e s , t h e herd remained  and  With t h e stationary  throughout the d u r a t i o n of the observation p e r i o d .  During  scan  collected  at  exceptions,  sampling  in  dusk  dawn  of  in  the  and  December,  no movement  movement d u r i n g t h e  nights  of  1977  and  successive animals  colder  January,  sampling  overnight.  months  is  more  1978,  days This  observations  showed, may  restricted  with  rare  suggest  that  than  during  n i g h t s o f more temperate s e a s o n s .  2.  Seasonal a c t i v i t y  budgets  Average d a y l i g h t hours devoted t o f e e d i n g by t h e herd members ranged from 5.32 h r s / s a m p l e day and 5.27 h r s / s a m p l e day f o r December and J a n u a r y , t o 9.22 h r s .  i n September  (see T a b l e  IX).  However,  months showed no c o n s i s t e n t t r e n d and were a l l  means f o r  respectively the  remaining  w i t h i n one hour o f t h e  mean o f 7.43 h r s / s a m p l e d a y , r e s u l t i n g i n an i n s i g n i f i c a n t c o r r e l a t i o n  yearly between  f e e d i n g t i m e and d a y l e n g t h (r = 0 . 5 1 ) .  Regardless of a mid-winter increase i n d a i l y of d a y l i g h t daylength monthly  to  hours devoted t o bedding proved t o be s i g n i f i c a n t l y  (r = 0 . 9 2 ) , 0.77  peaking at  hrs/sample  values increased i r r e g u l a r l y bedding  bedding t i m e , t h e average number  times  began  an  day  5.75 in  hrs/sample  November.  correlated  day i n June and  Although  decreasing  December and  January  t o 1.6 and 2.2 h r s / s a m p l e day, r e s p e c t i v e l y ,  orderly  monthly  F e b r u a r y t o 5.51 h r s / s a m p l e day i n May. day.  49  climb  from  1.47  hrs/sample  The y e a r l y average was 3.0  to  day  the in  hrs/sample  \u000CTable IX. Month May  Average d a y l i g h t a c t i v i t y budgets of the adult ewes, by month.  # days/ month 7  Mean length of sampling days (hrs)  Feeding Time (hrs)  % of  Daylength  Bedding Time (hrs)  % Of  Daylength  Travel time (hrs)  % of  Daylength  Standing % Of Time Daylength (hrs)  \"Other\" Time (hrs)  % of Daylength  15.00 (0.0)( )  7.40 (0.87)  49.3  5.51 (0.60)  36.7  0.97 (0.41)  6.5  0.67 (0.49)  4.5  0.46 (0.37)  3.1  6  16.04 (0.70)  7.90 (1.13)  49.3  5.75 (1.03)  35.8  0.64 (0.36)  4.0  1.09 (0.80)  6.8  0.65 (0.41)  4.1  July-Aug.  8  16.21 (0.59)  8.38 (1.05)  51.7  5.39 (0.97)  33.2  1.03 (0.51)  6.4  0.99 (0.65)  6.1  0.42 (0.33)  2.6  September  5  12.70 (0.48)  9.22 (1.40)  72.6  1.85 (0.89)  14.6  0.72 (0.48)  5.7  0.58 (0.39)  4.6  0.33 (0.30)  2.6  October  6  10.75 (0.42)  8.03 (0.98)  74.7  1.37 (0.67)  12.7  0.60 (0.48)  5.6  0.58 (0.48)  5.4  0.17 (0.25)  1.6  November  7  9.39 (0.49) .  7.65 (0.84)  81.5  0.77 (0.69)  8.2  0.40 (0.29)  4.3  0.42 (0.34)  4.5  0.13 (0.20)  1.4  %  1  June  -  December  4  8.56 (0.24)  5.32 (1.39)  62.1  1.60 (1.30)  18.7  0.81 (0.47)  9.4  0.73 (0.56)  8.5  0.13 (0.20)  1.5  January  3  9.5 (0.00)  5.27 (1.28)  55.5  2.20 (1.04)  23.2  0.71 (0.37)  7.5  1.22 (0.61)  12.8  0.11 (0.20)  1.2  February  5  10.25 (0.40)  7.14 (1.62)  69.7  1.47 (0.95)  14.3  0.46 (0.36)  4.5  1.07 (0.84)  10.4  0.10 (0.16)  1.0  March  4  11.44 (0.59)  8.33 (0.80)  72.8  2.10 (1.04)  18.4  0.36 (0.27)  3.1  0.49 (0.28)  4.3  0.14 (0.26)  1.2  April  3  14.52 (0.14)  7.13 (0.94)  49.1  4.61 (0.83)  31.7.  1.69 (0.85)  11.6  0.91 (0.47)  6.3  0.19 (0.24)  1.3  x = 12.21  x = 7.43 r = 0.5l( )  x = 3.0 r = 0.92*  2  x = 0.76 r = 0.51  x = 0.80 r = 0.24  x = 0.26 r = 0.85*  Nov. '78 (1 day)  x = 9.75  x = 5.42 (0.76)  55.6  x = 3.04 (0.57)  31.1  x = 0.44 (0.25)  4.52  x = 0.75 (0.41)  7.70  7 = 0.10 (0.13)  1.14  Dec. '78 (1 day)  x = 9.0  x = 6.33 (0.55)  70.3  x = 1.23 (0.60)  13.7  x = 0.55 (0.50)  6.1  x = 0.96 (0.58)  9.6  x = 0.03 (0.09)  0.3  (1) = values i n parenthesis are standard d e v i a t i o n s (2) = c o r r e l a t i o n c o e f f i c i e n t (with daylength) *'s i n d i c a t e s i g n i f i c a n t c o r r e l a t i o n (p= &lt; 0.05)  \u000CD a i l y t r a v e l t i m e showed no o b v i o u s seasonal ranged  from  1.69  significantly occurred  in  (April)  to  0.36  pattern during the year.  hrs/sample  day  c o r r e l a t e d t o daylength (r = 0 . 5 1 ) . May  (0.97  hrs/sample  day)  and  July  in  were  not  R e l a t i v e l y high values  also  -  March  August  and  Values  (1.03  hrs/sample  day).  Daily  standing  0.24),  showed  occurring January  to  remained values  in  time, two  the  peaks  or  h r s / s a m p l e day  significantly the  and c o l d e s t  above  irregularly  correlated  study  respectively).  slightly  fluctuated  not during  hottest  February  at  also  year,  with  months  of  During  these  1 hr/sample between  0.42  day.  the  to the  year  the  hrs/sample  highest (June  periods  For  daylength  August,  standing  (Nov.)  times months,  and  0.91  (April).  Time devoted t o \" o t h e r \" a c t i v i t i e s  (playing,  interacting,  maternal  behaviour)  d u r i n g t h e d a y l i g h t hours proved t o be s i g n i f i c a n t l y c o r r e l a t e d t o d a y l e n g t h = 0.85),  p e a k i n g i n May, June and J u l y  respectively) February. by A p r i l  =  values  to  remaining  day  (r  (0.46,  and then d r o p p i n g g r a d u a l l y  0.65 and 0.42  hrs/sample  (r  day,  t o a low o f 0.10 h r s / s a m p l e day  in  Values began i n c r e a s i n g i n t h e s p r i n g , r e a c h i n g 0.19 h r s / s a m p l e day 1978.  Because d a y l e n g t h s  varied considerably  on a seasonal  a c t i v i t y times provided marginally useful  s a m p l i n g days devoted t o v a r i o u s a c t i v i t i e s It i s  actual  and sometimes d e c e p t i v e  on t h e seasonal t r e n d s o f t h e s e a c t i v i t i e s .  standardized set of values.  basis,  daylight  information  Consequently, the proportions  were c a l c u l a t e d t o p r o v i d e a more  t h e s e p r o p o r t i o n s which a r e d e a l t w i t h  S e c t i o n C2 o f D i s c u s s i o n .  51  of  in  \u000CUnlike actual  feeding t i m e s , the p r o p o r t i o n of d a y l i g h t  varied dramatically from A p r i l  between s e a s o n s .  i n c r e a s e d i n an o r d e r l y  and then c l i m b e d i n February and March t o 69.7 and  generally  followed  d e c l i n i n g from peak s p r i n g v a l u e s November.  December  Winter  and J a n u a r y ,  F e b r u a r y and March,  bedding  a reversed trend to that  (31.7% i n A p r i l ,  proportions  respectively,  and then  no  seasonal  of  feeding,  36.7% i n May) t o o n l y 8.2%  increased  to  dropped  18.7  to  and  23.2%  in  and  18.4%  in  14.3  respectively.  The p r o p o r t i o n o f d a y l e n g t h devoted t o t r a v e l , showed  fashion  respectively.  Bedding p r o p o r t i o n s  in  foraging  (49.1%) t o November (81.5%), dropped t o 62.1 and 55.5% i n December  and J a n u a r y , r e s p e c t i v e l y , 77.8%,  Values  hours spent  trend,  ranging  between  s i m i l a r to actual  values  of  3.1% t o  months o f May t o November i n c l u s i v e , J a n u a r y , February and March. p r o p o r t i o n s peaked i n A p r i l  (11.6%) w i t h r e l a t i v e l y  daily  times,  7.5% f o r Travel  high values a l s o  the time  occurring  i n December (9.4%).  Standing  time  proportions  also  showed  no  seasonal  trend.  Relatively  high  v a l u e s o c c u r r e d i n J a n u a r y (12.8%), December (8.5%) and F e b r u a r y (10.4%), w i t h v a l u e s f o r t h e r e m a i n i n g months f l u c t u a t i n g i r r e g u l a r l y (March)  and 6.8% ( J u n e ) .  Unlike  actual  between 4.3%  standing times/sample  day,  standing  t i m e p r o p o r t i o n s d i d not demonstrate a secondary peak i n summer.  The p r o p o r t i o n o f d a y l e n g t h devoted t o p a t t e r n as a c t u a l t i m e s . d e c l i n e d i n a gradual  \"other\" a c t i v i t i e s  followed a  similar  Peak v a l u e s o c c u r r e d i n May (3.1%) and June (4.1%),  f a s h i o n t o 1.0% i n F e b r u a r y ,  and 1.3% i n March and A p r i l ,  respectively.  52  and then i n c r e a s e d t o  1.2  \u000CThe h e r d ' s d i u r n a l December  1978  Although  times  November 14,  budget v a r i e d c o n s i d e r a b l y on s a m p l i n g days i n November and  from  that  devoted  demonstrated to  during  travelling,  a  comparable  standing  and  1978 were not u n l i k e t h e mean d a i l y  \"other\"  values  \"other\"  activities  sampling days. spent  grazing  also  in  1977.  activities  for  t h e herd reduced t h e i r g r a z i n g t i m e and i n c r e a s e d t h e i r than two hours from 1977 v a l u e s .  period  November,  1977,  bedding t i m e by more  Times devoted t o s t a n d i n g , t r a v e l l i n g ,  varied only  slightly  between December 1977 and 1978  by more than  one  hour  over  the  December  average  devoted t o  grazing  cratering  cratering  times  time for  demonstrated  forage.  averaged  0.2  This  by  the  varied  hrs/sample  day  herd  in  1978,  considerably during  snow  time  1977 mean  d a i l y v a l u e , w h i l e bedding t i m e decreased by a p p r o x i m a t e l y 0.4 h o u r s . total  and  However, d u r i n g i n c l e m e n t weather on December 13, 1978, increased  on  0.8  Of t h e hrs  was  from 1977,  when  accumulations  of  December, d e c l i n i n g t o 0 h r s / s a m p l e day once m i l d temperatures removed much o f t h e snow c o v e r i n l a t e December.  In a d d i t i o n fluctuations  to these  seasonal  changes  were a l s o e v i d e n t .  in  the  As d e s c r i b e d  l i n e a r model used t o s t a t i s t i c a l l y  -  social  contributed  no  group  interaction  significant  in  activity  Section  budget,  of  term.  variance  to  the  in  s a m p l i n g day and t h e  Although  the  statistical  daily  B2 o f Methods,  a s s e s s between group d i f f e r e n c e s  and bedding t i m e s a l s o a s s e s s e d t h e e f f e c t s day  herd's  grazing sampling  interaction model,  the  term  there  was  s i g n i f i c a n t day t o day v a r i a t i o n i n t h e h e r d ' s a c t i v i t y budget f o r most months of  the  year.  May  to  September  months i n which s i g n i f i c a n t devoted t o a l l but  one  five activity  activity  significant  daily  December  and  February  day t o day f l u c t u a t i o n s were p r e s e n t categories.  (standing, variation  inclusive,  standing  In O c t o b e r , and  \"other\",  i n the times  November and A p r i l , respectively)  i n d u r a t i o n , w h i l e i n March, bedding a l o n e  53  were  all  showed varied  \u000Cdaily.  January was t h e  o n l y month i n which t h e  herd's  activity  budget  was  c o n s i s t e n t from day t o day.  D.  Effects of Physiological  As p r e v i o u s l y  described  C o n d i t i o n on D a i l y A c t i v i t y  i n S e c t i o n B3 o f  Results,  intermediate status died during the w i n t e r . and  bedding  times  of  healthy  and  sick  only  grazing months  dominant  animals,  o r bedding t i m e s  animals  tested.  However,  c l a s s of animals &lt; 0.05)  no s i g n i f i c a n t  of  sick  in  (Table X a ) .  l o n g e r than h e a l t h y  t h e two g r o u p s .  but s i c k  dominant  and  grazing  November  and  between  the  classes.  animals  evident  existed for  within  any  of  the  the  three  intermediate  In O c t o b e r , s i c k a n i m a l s grazed s i g n i f i c a n t l y a n i m a l s , a l t h o u g h bedding t i m e s were s i m i l a r  In December, j u s t  t i m e s were s i m i l a r  were  October,  differences  and h e a l t h y  differences  ewes o f  T h e r e f o r e , comparisons o f  December were p o s s i b l e o n l y w i t h i n t h e s e two s o c i a l  Among t h e  Budgets  p r i o r to the majority  a n i m a l s bedded s i g n i f i c a n t l y  (p for  of deaths,  grazing  l o n g e r than  healthy  animals.  In March and A p r i l , ewes from each o f t h e t h r e e s o c i a l c l a s s e s were s u p p o r t i n g late  stages  of  fetal  development,  pregnant and non-pregnant  ewes t o  enabling  grazing  be compared w i t h i n  and  bedding  each c l a s s  times  (Table  of Xb).  Pregnancy demands d i d not appear t o a l t e r a c t i v i t y budgets a p p r e c i a b l y , and no significant within  every  differences class,  were  pregnant  detected ewes  in  between t h e April  did  t i m e s than non-pregnant ewes, but not s i g n i f i c a n t l y  54  social  groups.  demonstrate so.  longer  However, grazing  \u000CT a b l e Xa - Average g r a z i n g and bedding t i m e s o f h e a l t h y and s i c k ewes (October t o December 1 9 7 7 ) , i n hours  Dominants  Intermediates  Feed, t i m e s Oct. Nov. Dec.  Bed. t i m e s Oct. Nov. Dec.  Healthy  8.10  7.82  5.28  1.48  0.55  1.38  7 . 7 8 a l 7.29  5.48  1.11  0.66  1.2ia  Sick  7.75  7.56  5.69  1.42  0.73  1.44  8.32\u00B0 7.67  5.08  1.32  0.87  2.28b  1  Feed, t i m e s Oct. Nov. Dec.  w i t h i n any g i v e n column, v a l u e s w i t h d i f f e r e n t (p &lt; 0.5)  Bed. t i m e s Oct. Nov. Dec.  s m a l l case l e t t e r s a r e s i g n i f i c a n t l y  T a b l e Xb - Average g r a z i n g and bedding t i m e s o f pregnant and non-pregnant ewes (March, A p r i l  Domi nants  Intermediates  different  1 9 7 8 ) , i n hours  Subordinates  Feed, t i m e s Mar. Apr.  Bed, t i m e s Mar. Apr.  Feed, t i m e s Mar. Apr.  Bed, t i m e s Mar. Apr.  Feed, t i m e s Mar. Apr.  Bed, t i m e s Mar. Apr.  Pregnant  8.42  7.49  1.73  4.42  8.00  7.58  2.13  5.00  8.71  7.33  1.94  4.58  Non-pregnant  8.81  7.08  2.06  4.50  8.37  6.87  2.56  4.83  8.06  6.50  2.28  4.54  \u000CEnergy E x p e n d i t u r e E s t i m a t e s f o r t h e A d u l t Ewes  E.  The e s t i m a t e d mean basal  metabolic  rate  for  the  adult  c l e a r s e a s o n a l t r e n d s , o t h e r t h a n an e l e v a t e d l e v e l other  periods  Kg-1  hr-1  in  0.93  Kcal  of  the  May  and  kg-1  Values  ranged  October  to  year  (Table  June,  hr l  in  _  February,  July  between  before  BMR's  respectively, the  irregularly  XI).  ewes demonstrated  no  i n the spring r e l a t i v e  to  reached  dropping  -  August  1.18  and  demonstrating  1.53 to  and  a  Kcal  increased  early  _  1.60  yearly  kg-1  Kcal  low  September  1.06  1.50 and 1.49 Kcal kg-1 h r l i n March and A p r i l ,  and  of  periods. hr l  from  _  spring  levels  of  respectively.  E s t i m a t e s o f t h e average h o u r l y energy expended by t h e herd members d u r i n g a typical  daylight  Values  peaked  routine  in  respectively), hr l _  in  ranged  the  dropped July  -  irregularly  to February. kg-1  April,  hr l. -  climbed  to  followed  a  May  June  to  and yearly  August  and  between  2.47  the Kcal  and  of  hr l.  BMR's  (Table  XII).  2.29  Kcal  kg-1  hr-1,  1.52  and  1.54  Kcal  kg-1  Kcal  respectively kg-1  hr l  and  from  _  then  October  i n c r e a s e d c o n s i d e r a b l y t o 2.04 pregnancy Lactation  -  to  2.39,  periods,  1.61  cost  inclusion kg-1  of  September  1.83  pattern  (2.29,  lows  In March, t h e a c t i v i t y With  similar  costs, costs  Kcal  April's  value  increased  May's  v a l u e t o 3.13 Kcal kg-1 h r - l .  When e x p r e s s e d as m u l t i p l e s irregular  but  behaviour  proved  August  limited to  ( 1 . 6 3 x BMR),  o f BMR, average d a i l y a c t i v i t y  monthly  be  slightly  September  fluctuations more (1.67  (Table  expensive  XII).  relative  x BMR) and December  l e a s t e x p e n s i v e i n June ( 1 . 4 3 x BMR) and March ( 1 . 3 6 x BMR). between 1.52 and 1.56 i n t h e r e m a i n i n g months.  56  costs  demonstrated  Normal to  daylight  BMR i n  (1.63  July  x BMR)  Multiples  and  ranged  \u000Cll C K i r - l Z  CT4  Jol ft o I  O  m  t\u00BB e  f l  *c  o  ^  \u2014  \"  a-  j  ^  CO  o-  co e  ^  cr c  \u2014  r  i  t\u00A3&gt;  (M  c  \u2014  f\u00BB  cr \u2014  r-~  m  CO  fsj  C\\J  ID CVJ  C  lO  c  c  t  pn  j  \u00ABr  ^  O'  m  i  n  \u2014  ^  \u00ABJ  j  in ^  +-&gt;  O  i\u00AB r c | ^\u00BB \u00AB i \u2014 C \u2022\u00A9 E[ ro  IC d  \u2014 \"  in cc  CN)  a\\  *T *o t\\j  n m  m  CM  Crm  CM  \u2022 PJ  3 CD  3  -a  i! |  f  4-&gt;  S-  O  .a rO 4-&gt; CD E  ro c/i ro -Q CD cn ro S&lt;D &gt;  H?l *| Ifc  R  S  |S| a  s  rO  i ft  R  5  5  c  s  s  s  gf  s  l  l  ii il  p  cr cr.  P  s  : | ii ii s|  ii mn  R  R  R  R  R  R  R  ft  j  S  5  5  s  5  5  5  5  s  \"  = I:  t  \"  . . . .  f  ;  i i  B  I  T5  OJ  5  E  | | | 2i  !!!!!!!!  iliU!I! 511j | H i  \u00A3  \u00A3  \u00A3  \u00A3  \u00A3  \u00A3  \u00A3  \u00A3  \u00A3  \u00A3  5  5  5  3  5  5  5  S  S  S  11  j  11 f1  ? ? M M M  Mi M S  X  s  is inni $ ?nnnn  CD  o  g  eil i ! II \u00AB! i l \u00A71 i i i !  ro  to CD +-&gt; ro S-  j  E  ca)  i i i i i i i i  57  !  I  2  J  H  *i  !  I  J |  5!  \u000Co \u00BB* I -  is-g I  cr cr  ID  c  c  o  co T3  O  in  o-  e  O  -a  CO  Oi  CO  &gt;, OJ re  O) S-  +J  \u2022a c &lt;D cu X OJ l&lt; cu c CU  S  \u00AB  ro  m  ^I  \u00AB7  &gt;&gt; -3  ~-  -a I fc.  C -  \u2022o cu  CTi  CT&gt;  O  ro  rO S-  cu &gt; ui  X  m co  C Q.\u2014 \"O  CD  Dl  E  D&gt; (_  58  \u000CDISCUSSION  A.  Social  1.  Organization  Dominance h i e r a r c h y o f t h e a d u l t ewes  The s o c i a l  behavioural  repertoire  from  recognized  in  that  behavioural performed  by  of the adult  previous  studies  patterns  of  rams  described  females  in  this  study,  ewes was c o n s i d e r a b l y  for  by  Geist  rams.  (1971),  only  eight  17 were  being conspicuously absent.  That b i g h o r n ewes would have r e l a t i v e l y  few horn  displays  considering the l i m i t e d  of a d u l t s . social  Geist  involving  the  displays  not s u r p r i s i n g ,  patterns  Of  horn  is  with  bighorn  reduced  variability  (1971, p. 179) s u g g e s t s t h a t rams can a s s e s s a s t r a n g e  s t a t u s by t h e l a t t e r ' s  horn s i z e and, as a r e s u l t ,  e v o l v e d as a n o n - v i o l e n t means o f e x h i b i t i n g s o c i a l ewes,  such  displays  would  indistinguishable differences where horn o r a n t l e r patterns  which  pronounced buffalo  sizes  caffer),  relatively  small,  individual  recognition  eliminating  the  goat  little  of adults body  Sinclair groups  than  of  It  animals  many  social  established.  59  displays  have  However, amongst  because  of  the  often  societies  subtle differences,  behaviour  horn  development  Geist is  also  such  d e v e l o p s between herd members for  ram's  In most u n g u l a t e  americanus), 1974).  size  horn d i s p l a y s  status.  value  show o n l y  rather  (Oreamnos  consistent  need  have  i n t h e i r horn s i z e s .  exaggerate  (mountain  (Syncerus  i n horn  once  as  1964;  East  possible the  that,  1973),  hierarchy  more  African  captive  (Shackleton a  are  has  in  herd, thus been  \u000CTwo a d d i t i o n a l  patterns  (horn  urination  by s u b o r d i n a t e s ,  anoestrus  females  observed f o r clash,  the  to  interlocking.  similar  aggressive  ewes.  impossible  wrestling, t o the  males,  large  rams  Shackleton  urination  described  Horn w r e s t l i n g  in  from  appeared  where  basal  horn  Geist  ewes  Dominant  ewes,  and  rams  once  after  aggressive  confronted  a g g r e s s i o n towards t h e  by  disputes  were  also  be an e x t e n s i o n diameters  of  would  the  prevent  this  approaches posture,  by  would  these show  animals.  no  further  i n t e r a c t i o n s between t h e c a p t i v e ewes i s a  biologically  sound,  considering  a  Such a s o c i a l  female's  bioenergetic  To maximize her r e p r o d u c t i v e s u c c e s s , a ewe must m i n i m i z e energy  expenditures effort  and  1971)  b e h a v i o u r a l q u a l i t y not uncommon f o r female u n g u l a t e s o c i e t i e s .  constraints.  oestrus  subordinate.  The i n f r e q u e n t o c c u r r e n c e o f s o c i a l  is  squat-  The u r i n a t i o n response o f s u b o r d i n a t e ewes was d i r e c t e d both a t  dominant  strategy  and  response o f  by to  1973,  on a c t i v i t i e s  (Geist  1971).  and p l a y ,  not  Since  vital  to  maintenance  interactions,  are e n e r g e t i c a l l y  very  or t o  particularly costly  her  reproductive  prolonged  dominance  and o c c a s i o n a l l y  damaging,  t h e s e a c t i v i t i e s w i t h i n t h e female s o c i e t y s h o u l d be g r e a t l y reduced i n number and  duration,  compared  with  those  e v i d e n t among t h e c a p t i v e a n i m a l s . 67% more a g g r e s s i v e  interactions  of  males.  Such  a  reaction  The t w o - y e a r o l d ram i n t h e herd with  the  single  yearling  from June t o December 1977 than t h e most a g g r e s s i v e  adult  restricted  their  any r i t u a l i z e d  playlike  dominance  activities  to  late  fights, spring  as  clearly initiated  male.herd  member  ewe i n i t i a t e d  14 p o t e n t i a l a d u l t ewe opponents d u r i n g t h e same p e r i o d o f t i m e . ewes d i d not e x h i b i t  was  did  with  In a d d i t i o n , the  rams,  and summer months  and when  their physiological  and f o r a g i n g c o n d i t i o n s were a t an optimum annual  level.  Reduced a g g r e s s i o n  amongst  reported  females  in  60  comparison t o males  has been  \u000Cfor  several  Joubert  ungulate  1974)  and  species,  oryx  (Oryx  including beisa,  roan  Walther  antelope  (Hippotragus  1978).  The  rarity  equinus, of  actual  dominance f i g h t s between female mountain sheep has a l s o been r e p o r t e d by G e i s t (1971) and B l o o d ( 1 9 6 3 ) .  That t h e c a p t i v e ewes c o u l d s u c c e s s f u l l y  c o e x i s t w i t h such a q u i e s c e n t  s t r u c t u r e was p r o b a b l y t h e r e s u l t o f r e s o u r c e a v a i l a b i l i t y . f u n c t i o n as a r e l a t i v e l y their  rigidity  hierarchies rams  were  efficient  would be e x p e c t e d w i t h l i m i t e d , two  most  significant  maintenance and r e p r o d u c t i v e  amongst  of  the  their ewes  social to  distributed relatively  status,  attain  diffused  low d e n s i t y  breeding  captive  vary  resources.  ewes  privileges.  Forage and required  dominance  Forage,  periods.  Geist  per u n i t  (1974)  sheep,  by e x p l o i t i n g  suggests  area w i l l  that  in  a relatively  it  bred  turn,  was fall,  \"dispersed  and  against  can be s p e c u l a t e d  dispersed  were a b l e t o c o e x i s t w i t h a minimum o f f o r a g e d i s p u t e s .  for  disputes  lead to a s e l e c t i o n  Consequently,  in  Rigid  However, ewes were  n e g a t i n g t h e need f o r  f o o d c o m p e t i t i o n by o v e r t a g g r e s s i o n . . . \" . the  the  often  homogeneously o v e r t h e study a r e a f o r much o f t h e  spring  food o f  of  but  resources.  which  respectively.  Hierarchies  allocation  localized  resources  success,  w i n t e r and e a r l y  that  resource  depending on t h e s u p p l y and d i s t r i b u t i o n  the  regardless  means o f  social  food  T h i s was  resource,  particularly  t r u e a f t e r t h e range p l a n t s had c u r e d t o a low n u t r i t i v e s t a t e and t h e animals were d i s p e r s e d  to t h e i r  feeding  disputes  \"point\"  or  greatest  became more  localized  degree d u r i n g f o r a g i n g  frequent  resources,  such  when t h e as  the  animals  water  bouts. were  trough  Conversely,  dependent  and  upon  supplemental  hay.  The preponderance o f bedding d i s p u t e s l i k e l y the  herd members  of  one o f  several,  r e s u l t e d from t h e repeated use by  apparently  61  preferred  bed  sites  during  \u000Cmajor  resting  areas,  periods.  creating  This  a situation  interactions.  It  is  behaviour  concentrated  conducive to  doubtful  that  an  animals  into  social  confrontations  actual  shortage  of  localized  and  eventual  bedding  sites  i n i t i a t e d t h e s e bedding d i s p u t e s .  The  relative  crowding  by t h e  than a lack the  abundance  of  perimeter  of  positional  herd,  artificially  space.  Invariably,  fence  momentarily  before  frequently  initiate  of  the  enhanced  their  of  appeared  by t h e i r  to  result  captive  state,  from rather  a f o r a g i n g d r i v e would be i n t e r r u p t e d  enclosure,  redirecting a burst  disputes  causing  feeding  social  the  effort.  interactions  animals This  as  to  cluster  crowding  individual  by  would  distances  were b e i n g v i o l a t e d .  In  all  probability,  hierarchy  (i.e.  the  absence  localized,  limited  of  a  biological  resource)  requirement  was l a r g e l y  for  responsible  n o n - l i n e a r and somewhat d i s o r g a n i z e d h i e r a r c h y o f t h e c a p t i v e h e r d . a  rigid  hierarchy  without  energetically wasteful.  definite  resource  However, a d d i t i o n a l  t o the h i e r a r c h y ' s n o n - l i n e a r i t y . a temporary i n s t a b i l i t y  a  gains  would  rigid  for  the  Enforcing have  been  f a c t o r s may a l s o have c o n t r i b u t e d  Dominance r e v e r s a l s and t r i a n g l e s a r e o f t e n  common t o a new assemblage o f a n i m a l s  (Wilson  1975).  When f i r s t t r a p p e d , t h e c a p t i v e herd was comprised o f a n i m a l s o f a t l e a s t two and p o s s i b l y mutually  several  different  interacted.  Therefore,  a n i m a l s had no r e l a t i v e unclear.  In  maternal  December  groups which p r e v i o u s l y  confined  to  a  common a r e a ,  may not many  s t a t u s t o each o t h e r and t h e h i e r a r c h y was and  dominance r e - o r g a n i z a t i o n ,  January,  winter  mortalities  forced  of  have these  initially even  more  p o s s i b l y e x p l a i n i n g t h e c o n t i n u e d low l i n e a r i t y  of  t h e h i e r a r c h y i n 1978.  Size  of  the  herd  is  an e q u a l l y  plausible  62  explanation  for  the  hierarchy's  \u000Cnon-linearity. flock  size,  Certain  animal  societies  their  hierarchies  above which  have  an i n h e r e n t  demonstrate  ( S c h j e l d e r u p - E b b e 1922, A l l e e 1952, i n W i l s o n 1 9 7 5 ) . original  size  of  the  captive  l i n e hierarchy to develop. showed  the  average  herd  Blood's  maternal  to  the  suggestion  non-linear  size  of  herd  was t o o  large  bighorns  for  a  socially,  the  (1973) d a t a , which  including  captive  the  straight  lambs  l e s s than 16 a n i m a l s f o r much o f t h e y e a r ,  that,  or  tendencies  It i s p o s s i b l e that  (1963) and S h a c k l e t o n ' s  group  y e a r l i n g s t o be s u b s t a n t i a l l y support  (16 a d u l t s )  critical  group  was  and adds  unusually  1arge.  Behavioural  s t u d i e s on o t h e r u n g u l a t e s o c i e t i e s  f i n d i n g s on s o c i a l  hierarchies.  have r e s u l t e d i n a v a r i e t y  Bighorn rams have a s t r o n g l y l i n e a r  of  hierarchy  ( G e i s t 1 9 7 1 ) , but spend t h e m a j o r i t y o f t h e y e a r i n r e l a t i v e l y  small,  cohesive  bands  1973,  personal  of  less  observations).  than  ten  It  not known i f  is  animals  (Blood  1963,  Shackleton  similar  straight  line  i n l a r g e r bands o f males which can e x i s t t e m p o r a r i l y . reported  for  the  hierarchies  of  a d u l t cow and b u l l R o o s e v e l t e l k Franklin  et  pronghorns 1974).  al_. (Kitchen  1974),  Unfortunately,  Landau's making  index  of  assessment  studies  reindeer,  the  and  of  their  cattle  herds adult  strength  of  antelope  bull  East  African  from W i l s o n findings  and dominance 1974;  and Fohrman  roan  linearity 1975)  difficult.  degrees o f l i n e a r i t y  Espmark  (Schein  of  the  is  The  (domestic  Espmark  not  study.  63  of  these of  with  cattle,  1974; American  in  1974), (Sinclair  expressed  majority  b i s o n ) , L o t t 1974; a d u l t cow E a s t A f r i c a n b u f f a l o , G r i m s d e l l 1974), s i m i l a r t o the f i n d i n g s of t h i s  L i e b 1968,  buffalo  many  1955),  (Joubert  in the h i e r a r c h i e s  reversals  roe d e e r ,  in  develop  L i n e a r i t y has a l s o been  ((Cervus c a n a d e n s i s r o o s e v e l t i )  mixed  linearity,  show v a r i a b l e  dominance t r i a n g l e s 1966;  1975),  domestic  hierarchies  (e.g.  studies, ungulate prominent  Wagnon et al_. bison  1969, i n  (Bison Sinclair  \u000CGiven  free  ranging  composition, develop  a  it  conditions  is  possible  linear  traditionally themselves  and  that  a  because  natural  maternal  However,  relatively  behaviourally  more  cohesive  hierarchy.  exploit  a  bands  considering  dispersed  of  group of  that  resource  energetic  size  and  bighorn these  and  animals govern  it  can  p o s t u l a t e d t h a t dominance i n t h e group would not be any more r i g i d l y o r e v i d e n t than i t was w i t h i n t h e c a p t i v e  S t a b i l i t y o f t h e a d u l t ewes s o c i a l  Relative social  stability system  is  is  a  to  required be  sheep  must  constraints,  age  be  enforced  animals.  system  characteristic  energetically  of  a  beneficial  hierarchy to  its  if  such  a  participants.  H i e r a r c h i e s presumably e n a b l e c o n s p e c i f i c s t o c o e x i s t as a s o c i a l  unit with a  minimum o f c o s t l y a g g r e s s i v e i n t e r a c t i o n s o v e r r e s o u r c e a l l o t m e n t  ( G e i s t 1971,  Wilson  1975).  disputes  An  unstable  and f r e q u e n t  fights,  dominance thus  system  losing  its  would energy  result  in  dominance  conserving  qualities.  Not s u r p r i s i n g l y , t h e c a p t i v e herd demonstrated o n l y minor dominance during the January.  14 month  study,  in  spite  of  the  herd  reduction  in  t h e i r lambs.  and  i n t h e h i e r a r c h y d i d so j u s t p r i o r t o o r a f t e r t h e b i r t h o f  C o n s i d e r i n g t h a t o n l y f i v e lambs were produced t h a t y e a r (two o f  them t o p r e v i o u s l y  e s t a b l i s h e d dominants),  it  would appear t h a t t h e  o f lambs may have been a c o n t r i b u t i n g f a c t o r t o t h e ewes' r i s e i n  stability  has  including dairy heifers Ross  December  The two a n i m a l s which showed i n c r e a s e s i n t h e i r dominance v a l u e s and  relative positions  Hierarchy  shuffling  and B e r g ,  1956),  1975) and roan a n t e l o p e  been w i d e l y  documented  for  many  presence  status.  ungulate  species,  ( B e i 1 h a r z e t al_. 1 9 6 3 ) , d o m e s t i c goats ((Capra h i reus) Roosevelt (Joubert  elk  calves  1974).  64  (Lieb  Scott  1968,  in  (1958, c i t e d  Franklin in Joubert  et  aK 1974)  \u000Csuggests  that  presumably with  hierarchies  are  relatively  stable  \"due t o t h e d r a s t i c and l o n g l a s t i n g e m o t i o n a l  fighting  shuffling  linear  and a v o i d a n c e . . . \" .  has  morphological  been  reported  or p h y s i o l o g i c a l  However, where  similar  members  changes.  to t h i s  of  a  a t t a i n the feeding p r i v i l e g e s  study,  hierarchy  dominants  internal these  hierarchies  will  experience  Miller  once t h e i r  social  high s o c i a l  needed i n t i m e s  Similarly,  pregnant does become more a g g r e s s i v e  Established  dominance  He a l s o suggested  have a r e l a t i v e l y  of  s h o r t a g e s t o meet r e p r o d u c t i v e demands.  d o m i n a t i n g p r e v i o u s l y dominant  connected  Espmark (1964) showed t h a t t h e  t h a t pregnant cows o r cows w i t h c a l v e s w i l l  that  permanent,  responses  s t a t u s o f r e i n d e e r d e c l i n e d upon t h e l o s s o f t h e i r a n t l e r s .  and w i l l  and  rank  of  food  (1971, 1974)  found  fawns were b o r n ,  often  animals.  often  show temporary  instability  and  increased  a g g r e s s i o n w i t h t h e i n t r o d u c t i o n o f \" s t r a n g e \" a n i m a l s t o t h e h e r d , as  animals  attain  their  respective  social  ranks  (Wilson  1975).  Such  xenophobic t e n d e n c i e s were not e x p r e s s e d by t h e c a p t i v e herd when a ewe from t h e Game Farm paddock e n t e r e d t h e study a r e a u n e x p e c t e d l y . would  appear  maintained, animals  that  the  herd's  was a r e l a t i v e l y  into  or  out  animals which, l i k e  of  the  ranges f o r  time  a  mean  in  addition  to  costly  being  open system e n a b l i n g t h e u n e v e n t f u l group.  Such  a  system  is  several energy  months o f expenditure  the year. at  a  time  loosely of  desirable  in  conspecifics  on  Aggression at of  it  passage  highly  sheep, o f t e n c o n c e n t r a t e w i t h u n f a m i l i a r  l o c a l i z e d winter would  hierarchy,  Consequently,  limited  this forage  avai1abi1ity.  Xenophobic t e n d e n c i e s a r e u s u a l l y pronounced i n t i g h t - k n i t , groups  typical  primates  of  (rhesus  many  species  monkeys  of  birds  (Macacca  65  (domestic mulatta),  rigidly  chickens, Southwick  structured  Wilson  1975),  1969,  in  \u000CW i l s o n 1 9 7 5 ) , and c a n i d s  ( w o l f ( C a n i s l u p u s ) , Mech 1 9 7 0 ) .  r e p o r t e d f o r some u n g u l a t e s p e c i e s male oryx  (Walther 1978).  the s o c i a l  i n c l u d i n g roan a n t e l o p e  However,  systems a r e r e l a t i v e l y  They have a l s o been  i n most f r e e  ( J o u b e r t 1974) and  ranging ungulate  open, s i m i l a r t o t h e c a p t i v e  societies,  bighorn  and new a n i m a l s a r e p e r m i t t e d t o j o i n e s t a b l i s h e d herds w i t h l i t t l e  herd,  aggression  a r i s i n g ( e . g . c a r i b o u , Bergerud 1 9 7 4 ) .  2.  D e t e r m i n a n t s o f dominance  Most b e h a v i o u r a l  s t u d i e s which have attempted t o e l u c i d a t e t h e d e t e r m i n a n t s  consequences o f dominance have been f a c e d w i t h c o n s t r u c t i n g incomplete i n t e r a c t i o n matrices  ( i . e . , where i n t e r a c t i o n s between a l l  p a i r s o f herd members were not o b s e r v e d ) . generally  been determined f o r  each animal values.  dominates.  The  non-parametrically  study a n i m a l s  of  rank  to  possible  from t h e p r o p o r t i o n o f  various  by rank c o r r e l a t i o n methods  opponents  ranked a c c o r d i n g t o  parameters (Kruskal  has  been  these  assessed  and Wall i s method,  Wagnon et ^1_. 1 9 6 6 ) .  More commonly, t h e dominance v a l u e s are t r a n s f o r m e d  angles  normally  which  coefficients  are  squares  D i c k s o n e t a]_. 1 9 6 6 ) .  highly  which  enable  faults  method  also  been  and can g i v e d e c e p t i v e few i n t e r a c t i o n s  rank because i t  probable  has  used  (Beilharz  R e g a r d l e s s o f t h e method o f a n a l y s i s ,  involved in r e l a t i v e l y o r low s o c i a l  and  into  correlation  ( B e i l h a r z and Myl rea 1963, B e i l h a r z et. _al_. 1966, C o l l i s  least  have i n h e r e n t  distributed  in  between dominance v a l u e s and v a r i o u s parameters t o be determined  parametrically Kaiser's  from  C o n s e q u e n t l y , dominance v a l u e s have  The herd members a r e then  relationship  hierarchies  or  occurrence  results.  et  1976).  al_.  1966,  t h e s e v a l u e s do  For example, an animal  (&lt; 5) may be g i v e n a d e c e p t i v e l y  high  i n t e r a c t e d w i t h a b i a s e d sample o f opponents, a  with  such  a small  must be taken when i n t e r p r e t i n g h i e r a r c h i e s  66  sample  size.  Therefore,  care  which have been c o n s t r u c t e d  from  \u000Csuch v a l u e s .  In t h i s  s t u d y , t h e use o f D . V . ' s  because  of  the  interacting. of i t s al.  number  of  pair  combinations  which  were  observed  B e i l h a r z ' s method o f a n g u l a r t r a n s f o r m a t i o n was employed because  r e l a t i v e ease and comparable performance t o o t h e r methods ( B e i l h a r z  1966).  that  limited  i n c o n s t r u c t i n g a h i e r a r c h y was a n e c e s s i t y  the  The major p o t e n t i a l dominant-subordinate  weakness o f t h e r a n k i n g relationships  between  pairs  o f t e n c o n c l u d e d from o n l y one o r two i n t e r a c t i o n s . repeated  interactions  cases.  In a d d i t i o n ,  different However,  opponents, there  significant.  is  would have i n d i c a t e d  system was t h e  were  I t may be p o s s i b l e  that  relative  some a n i m a l s from both h i e r a r c h i e s making  their  evidence  to  estimated suggest  D.V.'s  that  fact  animals  a reversed  of  et  rank  faced r e l a t i v e l y  somewhat  these  i n some few  questionable.  weaknesses  For example, B e i l h a r z and M y l r e a (1963) found g r e a t  were  not  similarities  between h i e r a r c h i e s c o n s t r u c t e d from s i n g l e and m u l t i p l e days d a t a and showed t h a t dominance r e v e r s a l s o c c u r r e d i n f r e q u e n t l y enough t o e n a b l e h i e r a r c h i e s be c o n f i d e n t l y ewes  with  determined  questionable  from r e l a t i v e l y  D.V.'s  in  this  few study  interactions. did  not  Secondly,  occupy  to the  unreasonable  p o s i t i o n s i n t h e h i e r a r c h y , c o n s i d e r i n g t h e i r opponents.  Therefore, since the  two  dominant-subordinate  hierarchies  relationships  in  this  which  had  study been  reflected observed,  the the  dyadic  correlation  between  various  parameters t o dominance c o u l d be a s s e s s e d w i t h some degree o f c o n f i d e n c e .  Younger adult  (&lt; 2 y e a r s )  were  not m o n i t o r e d  ewes and were e x c l u d e d from t h e a n a l y s i s  study. size  herd members  of  as  intensively  interaction  However, i t d i d appear t h a t from b i r t h t o e a r l y  as  data f o r  adult years,  the this  age and  (almost c o m p l e t e l y confounded f a c t o r s d u r i n g t h e growth p e r i o d ) were t h e  67  \u000Cpredominant  determinants  lambs  the  were  most  of  social  subordinate  status group  for  of  animals  ranked by s i z e , w i t h t h e l a r g e r lambs u s u a l l y encounters.  Lambs d i d  not  assume t h e  female.  by s i z e . three  and  the  study  appeared  area,  internally  i n i t i a t i n g and dominanting most  status  of  phenomenon observed i n r e i n d e e r (Espmark 1 9 6 4 ) . t h e next most s u b o r d i n a t e  In  their  dams a t  any t i m e ,  a  The two female y e a r l i n g s were  group, again c l e a r l y  ranked r e l a t i v e  t o each  other  As mentioned i n R e s u l t s , t h e t h r e e youngest a d u l t ewes o c c u p i e d t h e  lowest  positions  of  the  adult  female  hierarchy.  Had  suitable  age  e s t i m a t e s o f t h e o l d e r ewes been a v a i l a b l e , a h i g h c o r r e l a t i o n between age and dominance may have been e v i d e n t .  The f a c t  that  weights  and horn  dominance d u r i n g t h e study confounding invariably  factors. older  were  period l i k e l y  Animals  ewes w i t h  lengths  in  the  longer  consistently  resulted  1977  than  not  herd  average  correlated  from c e r t a i n which  adult  statistically  eventually horn  to  lengths  died  were  but  with  slightly  reduced average w e i g h t s because o f t h e i r emaciated c o n d i t i o n by e a r l y  winter.  S i n c e t h e i r dominance p o s i t i o n had been e s t i m a t e d p r i m a r i l y  summer and e a r l y  fall  interactions  deteriorated,  t h e r e was l i t t l e  by l a t e f a l l  and e a r l y w i n t e r ,  low c o r r e l a t i o n the  coefficient  1977 h i e r a r c h y .  In  before t h e i r  correlation  when w e i g h t s were c o l l e c t e d .  with  w e i g h t proved t o be s i g n i f i c a n t l y  the  condition  between average weight  between w e i g h t  1978,  physiological  and dominance  absence  of  and  had  status  Consequently,  value  these  from t h e  resulted  moribund  a for  animals,  c o r r e l a t e d w i t h dominance.  The d e c r e a s i n g s i g n i f i c a n c e o f horn l e n g t h t o dominance from 1977 t o 1978 was more  perplexing.  intermediate  status  Considering were  that  several  removed from t h e  \"long  herd  in  horned\" December,  animals  of  only  one would  have  e x p e c t e d t h e degree o f c o r r e l a t i o n between horn l e n g t h t o dominance t o show an  68  \u000Cincrease two  from 1977 t o 1978, and not t h e r e v e r s e .  relatively  sufficient level.  short-horned  to  individuals  cause t h e c o r r e l a t i o n  This  occurrence  alone  within  the  coefficient  was  possibly  However,  t h e promotion  hierarchy  in  t o drop t o an indicative  of  1978  of was  insignificant  the  borderline  importance o f horn l e n g t h as a d e t e r m i n a n t o f dominance i n t h e c a p t i v e ewes.  That  aggressiveness  correlation physical between clash  to  and  dominance  interactions rams  force  dominance  occur with  not is  not  amongst  attributes  surprising, ewes.  frequently  horn s i z e .  symbol.  physical  In  Among ewes,  considering  Geist  enough  to  such  showed  (1971)  the  the  infrequency  suggests  that  enable  these  animals  a system,  large  horns  however,  to  are  clashes associate  an  obvious and  horn s i z e d i f f e r e n c e s a r e t o o s u b t l e t o a l l o w an a s s o c i a t i o n between horn  size  than  large  individuals  through i n t i m i d a t i o n . particularly productive  could  ewes.  Consequently, p a r t i c u l a r l y aggressive attain  relatively  I t was apparent t h a t  aggressive,  possibly  During  actual  explaining clashes  adult  ewes,  consequently,  However,  has  little  those  where  from o t h e r  physical  B e i l h a r z jet aj_. was t h e  size,  bearing  i s l i k e l y of l i t t l e  Although these conclusions to  horn  the  attributes  strongest  rise  in  the  of  its  outcome  importance t o  of  weight  behaviour show  only  and C o l l i s  predictor  of  studies minor  (1976)  dominance  such  69  two  becomes in  variability disputes  the in and,  rank.  of  female  ungulate  differences  cattle.  Only  similar  societies,  between  both suggested t h a t in  the  significance  limited of  simply  new young became status  parameter's  rather  ranks  are based on l i m i t e d d a t a , t h e y do appear  social  (1966)  social  and horn w r e s t l i n g ,  because  on  high  some ewes w i t h  somewhat advantageous, which may e x p l a i n t h i s 1978 h i e r a r c h y .  are t o o  of  infrequent  and dominance s t a t u s t o d e v e l o p .  interactions  greatest  animals.  aggressiveness  Beilharz  et  aj_.  \u000Cshowed weight t o be an a d d i t i o n a l insignificant dominance.  s t r o n g p r e d i c t o r w h i l e both a u t h o r s  and n e g a t i v e c o r r e l a t i o n s  respectively  f o r h e i g h t at w i t h e r s and  S c h e i n and Fohrman (1955) showed age and w e i g h t t o be  indicators  o f dominance i n c a t t l e  but f u r t h e r  demonstrated t h a t  significant seniority  t h e h e r d , a f a c t o r confounded by age and w e i g h t , was t h e u l t i m a t e of  social  rank.  correlated  Dixon e t _al_. (1966)  t o dominance.  importance  in  Espmark  reindeer  within  found o n l y w e i g h t  (1964)  a  sex,  reported while  reported  that  size  and  to  be  in  determinant significantly  age was o f strength  greatest determined  dominance between t h e s e x e s .  Chase (1973, 1974, i n W i l s o n 1975) o f f e r s a \" m a g n i f i c a t i o n p r o c e s s \" to  explain  the  reason  aggressiveness. initiating  He  for  suggests  interactions  with  i n t i m i d a t i n g and f i g h t i n g successful  encounter.  encounters,  lifting  equilibrium is positions certain  the  the  reached.  occasional  or  a  individuals,  timid,  submissive  opponents,  and become i n c r e a s i n g l y  increases  animal  blow\"  are  Consequences o f Dominance  1.  Diet  in  the  dominance by  frequently  develop  improved  confident of  hierarchy  and  success until  with  each  in  later  a  social  s u b m i s s i v e a n i m a l s e v e n t u a l l y occupy \"Accidental suggested  events, by  Chase  such as f a t i g u e as  reasons  low on a  for  the  hierarchies.  comparisons  The absence o f d i f f e r e n c e s may  probability  dominance r e v e r s a l s which a r e observed i n  B.  ewes  the  upward  Conversely,  chance  between  aggressive  i n t h e dominance o r d e r . day  correlation  that  skills  This  high  hypothesis  simply  have  been  i n d i e t q u a l i t y between t h e t h r e e s o c i a l a  function  70  of  the  distribution  of  c l a s s e s of  their  forage  \u000Csupply.  During  regrowth  from  the  the  homogeneously  winter study  months,  site's  distributed  over  the  animals'  dominant  the  area  grasses, (wikeen  supplemental hay was p r o v i d e d , t h e herd s t i l l o f t h e day. dominant  diet  when e q u a l l y  to  good  initiate sites  costly  were  to  establish  exclusion wasteful  of  the  once t h e  time  spent  classes of animals.  with a limited  It  site  was  comm.).  Even  when  need  feeding  have  animal  a  needless  feed  did  initiator  the  had secured  supplemental  sites  that  been  for  aggression  enabling the  probable  would  the  over  Increased  is  dominant at  which  disputes  available.  position.  from  expenditure  Consequently,  between s o c i a l  likely  feeding  subordinates  energy  position.  a  fall  resource  t h e r e was l i t t l e  o c c u r a t t h e hay s u p p l y but most e n c o u n t e r s were b r i e f , only  primarily  u t i l i z e d n a t i v e f o r a g e f o r much  aggressive  readily  a  pers.  With such a d i s p e r s e d food r e s o u r c e ,  animals  was  a  did  active and  feeding not  vary  Had t h e hay been c o n t a i n e d w i t h i n a f e e d e r  number o f f e e d i n g spaces  (e.g. 2 or  have p l a y e d a much g r e a t e r r o l e i n r e s o u r c e  3 ) , then dominance  would  allocation.  There i s some i n d i c a t i o n t h a t dominance i n a group o f animals competing f o r a limited  point  individual. piglets  r e s o u r c e ensures Wilson  offers  certain  dominance r e l a t e d . meant  ready  (1975)  access the  an improved  reports  feeding  Espmark  on  advantages  (1964)  stations  (1974a, 1974b).  of  the  advantages  to established  results  that  food  supply  selection and  found t h a t  that  roe  of teat  high s o c i a l  feeding c r a t e r s ,  dominant  to  deer  the  high  anterior allotment status  in  but  reported  at  supplemental  ranking teats  by  may  be  reindeer  conflicting feeding  Some a u t h o r s have even used a l i m i t e d food supply t o  e s t a b l i s h dominance r e l a t i o n s between p a i r s o f a n i m a l s (Ross and B e r g , 1956).  An  extensive  dominance  literature  offers  feeding  search  uncovered  advantages  71  to  no  reports  animals  which  exploiting  showed a  that  dispersed  \u000Cr e s o u r c e , s i m i l a r t o t h a t found on t h e study s i t e . Geist  A hypothesis presented  (1974) s u g g e s t s t h a t t h e defense o f such a t h i n l y  s c a t t e r e d r e s o u r c e by  dominants i n c u r s c o s t l y a g g r e s s i v e e n c o u n t e r s w i t h o u t r e s u l t i n g i n gain  of  resources.  reasons  that  Geist,  defense  supplemental  hay  better  \"feeding  time  spent and  is  resources  presenting  of  also  Kruuk's  superabundant, energetically  (increasing  fighting\".  rate  (1972)  of  Dominance  food  further  resources  since  intake)  during  significant  suggestion,  localized  inefficient  in  effort  rather  feeding  is  such  as  would  be  than  wasting  perhaps  only  b e n e f i c i a l t o an animal when both f e e d and f e e d i n g spaces are l i m i t e d .  2.  A c t i v i t y budget comparisons  In any d e t a i l e d a c t i v i t y  budget c o m p a r i s o n , t h e method o f data c o l l e c t i o n  o f obvious importance t o t h e a c c u r a c y o f t h e e v e n t u a l a n a l y s i s . was t h e  only  available  procedure  suitable  for  such a l a r g e  and r e a d i l y  (Altmann 1 9 7 4 ) .  It  simultaneously  The s e l e c t i o n o f a sampling i n t e r v a l  d i c t a t e d by t h e t i m e r e q u i r e d t o c o l l e c t  adult herd.  site.  p r o v i d e d d a t a \" a p p r o p r i a t e t o e s t i m a t i n g p e r c e n t o f time spent  various a c t i v i t i e s \" primarily  Scan sampling  study  e n a b l e d d a t a on a l a r g e number o f group members t o be c o l l e c t e d  is  information  on t h e  in was  entire  A 15 minute i n t e r v a l , w h i l e o c c a s i o n a l l y e x c e s s i v e , was necessary  f o r a complete scan when t h e a n i m a l s were m o b i l e ,  widely  dispersed  or  both.  With such a l e n g t h y t i m e between s c a n s , t h e p e r c e n t a g e o f i n t e r v a l s devoted t o an a c t i v i t y can vary c o n s i d e r a b l y from t h e a c t u a l p e r c e n t a g e o f time spent that term  activity.  However,  activities  significant  such  as  f o r those of  this  margin o f  playing,  error  nursing,  is etc.  most and  pronounced was  not  in  the  durations  of  the  herd's  72  major  activity  classes  short  considered  l o n g e r d u r a t i o n such as g r a z i n g and b e d d i n g .  c o l l e c t e d i n t h i s manner were s e n s i t i v e enough t o show s i g n i f i c a n t variations  for  in  Data  day t o day (grazing,  \u000Cbedding).  Therefore,  comparisons o f such  they  were  also  considered  valid  for  between-group  activities.  A v a r i e t y o f scan s a m p l i n g i n t e r v a l s have been used i n t h e r e s e a r c h o f behaviour  but,  unfortunately,  no e v a l u a t i o n  w i t h i n a g i v e n study has been made.  of  Hancock  the e f f e c t s  (1954) used 1,  of  grazing  interval  2.5 and 5 minute  i n t e r v a l s at various times during h i s  r e s e a r c h on t h e g r a z i n g h a b i t s o f  cattle.  a  Van Dyke  (1978)  study on t h e a c t i v i t y  maintained  five  minute  budgets o f b i g h o r n s i n Oregon.  size  interval  dairy  throughout  The m a j o r i t y o f  his  studies  d e a l i n g w i t h l a r g e areas and group s i z e s have used a 15 minute sampling p e r i o d f o r data c o l l e c t i o n  The h y p o t h e s i s having  access  times  from  exploiting  ( r e i n d e e r , Thompson 1971; c a r i b o u , Roby 1 9 7 8 ) .  proposed f o r t h i s to  higher  subordinate a  relatively  quality herd  section  p r e d i c t e d t h a t dominant a n i m a l s ,  foraging  areas,  members.  dispersed  food  would  However, resource  have  reduced  S i n c e t h e a n i m a l s were a b l e t o e x p r e s s t h e i r  study  animals  where  social  status  average  grazing  significantly.  times  of  the  own f o r a g i n g s e l e c t i v i t y  foraging  social  classes  meant  with a  follow  would  not  that vary  T h i s proved t o be t h e c a s e .  The degree o f w i t h i n - c l a s s v a r i a b i l i t y three social  three  were  comparisons).  minimum o f i n t e r f e r e n c e o f o t h e r herd members, i t would l o g i c a l l y the  feeding  the  l i t t l e t o t h e a c q u i s i t i o n o f food (see p r e v i o u s s e c t i o n on d i e t  by  i n t h e g r a z i n g and bedding t i m e s o f t h e  c l a s s e s suggests the e f f e c t s of various b i o l o g i c a l  behaviour  of  animals.  subordinate animals d i f f e r e d  Throughout  significantly  the  and w i n t e r  months,  from each o t h e r i n t h e i r  p a t t e r n s i n o n l y two o f t h e seven months t e s t e d .  73  fall  f a c t o r s on t h e the  activity  From September t o December,  \u000Cthe  dissimilar  grazing  or  bedding  times  significant  variance to the s t a t i s t i c a l  the  deaths,  winter  variation  only  variability  in  their  budgets  showed  Dominant a n i m a l s  more months  than  The  group  appeared t o vary d i r e c t l y . become e v i d e n t  the  size  intermediate  model i n e v e r y month.  in January.  intermediates.  also  activity  of  the  However,  after  showed s i g n i f i c a n t  within-class  but  degree  of  However,  within-class  certain  when t h e c o m p o s i t i o n  added  significant  subordinates  and  animals  of  in  fewer  months  within-class  biologically each group  variation  influenced  is  than  trends  considered.  The  s u b o r d i n a t e group was comprised o f an age c o h o r t and c o n t a i n e d no members w i t h a detectable, aberrant physiological a wide (high  age  range  SGOT)  and,  which  condition.  from October  eventually  to  The dominant group l i k e l y  December,  died.  The  contained  intermediate  one  group  c o n t a i n e d a wide age range and, from October t o December,  five  Therefore, i t  that  partially  the  age and p h y s i o l o g i c a l variable  effects  of  behaviour  of  physiological  c o n d i t i o n were a t herd members. condition  on  least  A more d e t a i l e d grazing  sick  animal  also  likely  animals  e l e v a t e d SGOT l e v e l s , f o u r o f which d i e d i n w i n t e r .  is  with  possible  responsible  discussion  behaviour  had  is  for  on  the  presented  in  S e c t i o n D.  Studies  on  behaviour. heifers  domestic Hancock  under  importance  of  herbivores (1954)  identical genetic  have  shown  found l i t t l e environmental  as w e l l  as  age  the  effects  of  age  on  grazing  variability  i n the behaviour of  conditions,  indicating  factors  on t h e  twin  the  possible  of  animals.  behaviour  A l t h o u g h he d i d f i n d v a r i a b l e b e h a v i o u r between u n r e l a t e d s e t s o f s i m i l a r aged t w i n s , he a t t r i b u t e d t h e s e d i f f e r e n c e s t o d i f f e r e n t amongst t h e s e t s .  A r n o l d and M a i l e r  (1977)  l e v e l s of milk  found t h a t  animals  production  with  greater  p e r i o d s o f f o r a g i n g e x p e r i e n c e i n a g i v e n environment t a k e l o n g e r t o adapt new g r a z i n g regimes than a n i m a l s o f l i m i t e d p r e v i o u s e x p e r i e n c e .  This  a p l a u s i b l e e x p l a n a t i o n o f why age can a f f e c t  In l i g h t  74  grazing behaviour.  to  offers of  \u000Ccaptive  animals  in  this  study,  the  dominant  and  intermediate  ewes,  having  v a r i a b l e ages as w e l l as v a r i a b l e f o r a g i n g e x p e r i e n c e , each adopted a s l i g h t l y d i f f e r e n t f o r a g i n g p a t t e r n w h i l e a d j u s t i n g t o t h e new v e g e t a t i o n , r e s u l t i n g significant  behavioural  and l i m i t e d  previous  differences.  experience,  were q u i c k  f o r a g i n g s t r a t e g y f o r t h e study behavioural  variation the  site.  on  d e v e l o p a common  site  appropriate  some support when  and y e a r l i n g s  are assessed.  i n t h e h e r d , w i t h l e s s than one y e a r o f p r e v i o u s  native  site,  because o f young age  T h i s argument g a i n s  range,  showed  no  i n any o f t h e months t e s t e d .  study  to  d a t a on lambs born on t h e study  The t h r e e y e a r l i n g s experience  The s u b o r d i n a t e s ,  demonstrated  significant  within-group  Similarly,  remarkably  low  in  lambs  foraging  behavioural  born and weaned on  within-group  variability  in  a c t i v i t y budgets once s e p a r a t e d by s e x .  3.  Productivity  The l a c k  comparisons  of between-class  production differences  t o the s i m i l a r d i e t s of the three s o c i a l  can l o g i c a l l y  classes.  be  attributed  Without o b t a i n i n g a h i g h e r  q u a l i t y f o r a g e s u p p l y than o t h e r a n i m a l s , dominant ewes would not be expected to  demonstrate  production, could  be  greater  productivity.  although s t a t i s t i c a l l y  interpreted  in  terms  example, t h e average w e i g h t  insignificant,  of  gain  factors  of  of  result  seasonal  Shackleton bighorn (1971)  growth and  ewes  Shank  continue  suggested  y e a r s o f age.  as  that  well  as  press)  to  grow a f t e r  bighorn  Therefore, i t  other  Intermediates  (in  showed  rams  weight both  three  between-class did  Subordinates  appeared h i g h compared t o t h a t of  Certain  seem apparent  than  social  but  most For  from March t o August  which  and Dominants was l i k e l y fluctuations. Rocky  their  Mountain  of  age.  A and  by  California  Similarly,  maximum weight  the  review  at  i s p r o b a b l e t h a t t h e s u b o r d i n a t e ewes o f  75  in  status.  years  approach  trends  Geist 5 -  this  8  \u000Cstudy,  all  three  years  of  age,  were  still  demonstrating  some  physical  m a t u r a t i o n which c o n t r i b u t e d t o t h e i r March t o August weight i n c r e a s e .  This,  o f c o u r s e , was not t h e case f o r t h e o l d e r a n i m a l s o f t h e r e m a i n i n g two s o c i a l classes.  The  fact  that  all  three  subordinates  were,  on  h e a v i e r i n August 1978 t h a n i n September 1977 s u p p o r t s t h i s  The a p p a r e n t ,  although  statistically  insignificant,  average,  5.0  kg  suggestion.  preponderance  of  winter  m o r t a l i t i e s w i t h i n t h e i n t e r m e d i a t e s o c i a l c l a s s can p o s s i b l y be a t t r i b u t e d age r a t h e r than s o c i a l  status.  were  individuals  invariably  tooth  loss,  digestion  older  a condition  of forage.  which  for  much  affects  of  the  year,  the  only  these  a moderate number o f  class.  relationship review  found  offspring factors  female  between no  ungulate  dominance  research  production,  and  which  even though  societies  assessed a positive  the  and  poor  even  physical  exception  of  the  necessary relatively  compared t o  other  o f deaths o c c u r r e d w i t h i n  the  have  the  the  fully An  investigated  extensive  effects  of  correlation  Similarly,  literature  dominance  between  o f many u n g u l a t e  1971, p r o n g h o r n , K i t c h e n 1 9 7 4 ) .  and  t o dominate t h e young  interactions  productivity.  has been suggested f o r t h e males  sheep, G e i s t  mastication  relatively  with  died  gum n e c r o s i s  (Even WWW, a l t h o u g h dominant, was  intermediate social  of  animals  animals,  Consequently, the majority  studies  a n i m a l s which  considerable  prehension,  dominant a n i m a l s ) .  Few  Results,  unable t o e x p r e s s t h e a g g r e s s i v e n e s s  t o achieve high ranking s t a t u s . initiating  with  in  However, because o f t h e i r  dominant ewe WWW, were l i k e l y  docile,  (6+)  Age a l o n e enabled t h e s e  Subordinates i n the herd. condition  As d e s c r i b e d  to  species  these  on two  (mountain  attempts t o  compare  o t h e r measures o f t h e p r o d u c t i v i t y o f dominant and s u b o r d i n a t e animals such as  76  \u000Ct h e i r seasonal w e i g h t f l u c t u a t i o n s  and t h e i r o f f s p r i n g s '  growth and b e h a v i o u r  have not been r e p o r t e d .  S i n c e such p r o d u c t i o n comparisons r e q u i r e l o n g term o b s e r v a t i o n s o f a n i m a l s a captive state,  it  domestic  animals.  Beilharz  et  al_.  certain  were not  blood  research  animals  animals  \",  on  and C o l l i s  production.  correlated  which  In  a  cows,  (1976)  all  because any  Schein  found  Fohrman  (1955),  no r e l a t i o n s h i p  between  rate of  (1976)  indicative  of  of  found t h a t  nutritional  \"it  system  nutritional  levels status,  was u n l i k e l y  production  \" the  possible  and  Collis  He suggested t h a t  greater  primarily  nullified  dairy  considered  t o dominance. had  such r e s e a r c h has c o n c e n t r a t e d on  In a d d i t i o n ,  constituents,  dominant  farm,  not s u r p r i s i n g t h a t  (1966)  dominance and m i l k of  is  in  than  of  subordinate  management  advantage  that  for  on  the  dominant  individuals....\".  In a s i m i l a r f a s h i o n , t h e homogeneously d i s p e r s e d n a t u r e o f  the  study  forage  on t h e  nutritional  advantages  site and,  p r o d u c t i v i t y than s u b o r d i n a t e  C.  prevented  dominant  consequently,  animals  from  from o b t a i n i n g  demonstrating  greater  animals.  Forage A v a i l a b i l i t y and Herd B e h a v i o u r  Unlike  the  enabled  investigation  certain  of  hypothesis  the to  captive  herd's  be a c c e p t e d  or  social  rejected  p r o c e d u r e s , r e s e a r c h on t h e h e r d ' s seasonal d i u r n a l towards Instead, (i.e.  statistical causal  analysis,  factors  retroduction,  for  hypothesis behavioural  Romesburg 1981).  testing, trends  Although  organization, based on  felt  that  those  presented  below  offer  77  the  which  statistical  b e h a v i o u r was not o r i e n t e d and  could  inductive only  alternative  be  reasoning. hypothesized  hypotheses  have been generated from t h e same i n f o r m a t i o n c o l l e c t e d d u r i n g t h i s is  any  strongest  could  study,  interpretation  it of  \u000Cthe animals'  1.  behaviour.  Seasonal d i u r n a l  Seasonal  changes  from a complex concept  i n the diurnal interaction  expressed  Dudzinski 1978). the  herd's  nocturnal  patterns  by most Abiotic  behaviour. tendencies,  of  pattern abiotic  of  the captive  and b i o t i c  researchers  of  the  example,  onset  and  environmental  herbivore behaviour  f a c t o r s can e a s i l y For  although  these  termination  of  ( i . e . daylength)  resulted  variables,  (see A r n o l d  animals their  showed  diurnal  in  some  routine  C o n s e q u e n t l y , t h e time  i n f l u e n c e d t h e t i m i n g o f two o f  a n i m a l s ' major a c t i v e p e r i o d s ( i . e . e a r l y morning and l a t e e v e n i n g ) . f i n d i n g s have been r e p o r t e d i n o t h e r b i g h o r n s t u d i e s  a  and  be r e l a t e d t o c e r t a i n changes  g e n e r a l l y c e n t e r e d around dawn and dusk, r e s p e c t i v e l y . o f s u n r i s e and sunset  herd l i k e l y  (Mills  the Similar  1937, D a v i s 1938,  Davis and T a y l o r 1939, B l o o d 1963, G e i s t 1971, Van Dyke 1979) and from s t u d i e s of  domestic  1957,  livestock  Arnold  daylength  also  and  (Hughes and R e i d  Dudzinski  proved t o  1978).  be  1951,  Hancock  Although  not  inversely  related  to  1954,  Sheppard e t ^1_.  statistically the  number o f  assessed, active  and  n o n - a c t i v e p e r i o d s demonstrated by t h e herd d u r i n g t h e d a y l i g h t h o u r s , a t r e n d a l s o r e p o r t e d from o t h e r r e l e v a n t s t u d i e s .  A r n o l d and D u d z i n s k i  (1978)  stated  t h a t \" . . . i n l a t i t u d e s g r e a t e r than 35\u00B0 t h e breaks between g r a z i n g d e c r e a s e , as t h e days get s h o r t e r , grazing during  until  in mid-winter  some a n i m a l s w i l l  always  be  found  daylight\".  A l t h o u g h d e t a i l e d weather i n f o r m a t i o n was not a v a i l a b l e f o r t h e study s i t e ,  it  a p p e a r e d , from d i r e c t o b s e r v a t i o n , t h a t d a i l y weather p a t t e r n s had o n l y minor temporary conditions  effects in  on  the  herd's  December were l i k e l y  behaviour. responsible  78  For for  example, the herd's  cold  inclement  reduced  early  \u000Cmorning a c t i v i t y , a b e h a v i o u r a l 1971). and  Domestic l i v e s t o c k  Cheatum  1956,  in  p a t t e r n a l s o r e p o r t e d f o r S t o n e ' s sheep  ( A r n o l d and D u d z i n s k i  Moen  1973)  also  1978) and deer  demonstrate  particularly  c o l d days o r c o l d p o r t i o n s o f a d a y .  summer a l s o  appeared t o  eliciting  a brief  affect  but o f t e n  the herd's  premature  reduced  (Severinghaus  activity  during  Severe r a i n storms  behaviour  temporarily,  bedding p e r i o d by t h e  b e h a v i o u r has a l s o been r e p o r t e d i n domestic  (Geist  livestock  in  the  frequently  herd.  Similar  ( A r n o l d and D u d z i n s k i  1978).  In s p i t e  of t h e i r  apparent  influence  on b e h a v i o u r ,  both weather and d a y l e n g t h c o u l d not f u l l y in  herd  behaviour.  comparable different suggest  For  example,  temperatures, average  that  patterns  factors  must  and  a  and September,  daylength,  and budgets play  combined e f f e c t s  e x p l a i n t h e broad seasonal  from A p r i l  precipitation  activity  other  data  the  for  major  changes  months  demonstrated  the  role  herd.  in  of  of  vastly  This  would  influencing  herd  behaviour.  Based on i n f o r m a t i o n grazing  studies,  availability the  seasonal  p r o v i d e d from Wikeem's  it  is  postulated  that  and phenology) was l i k e l y diurnal  patterns  of  all  probability,  more d i r e c t l y  forage  condition  the  herd.  Although  it  weather p a t t e r n s ,  dictated  the  required  relevant  (i.e.  t h e f a c t o r most i n f l u e n t i a l  consequence o f both d a y l e n g t h and general in  r e s e a r c h and from o t h e r  was forage  forage  in a  shaping direct  condition,  foraging effort  and  subsequent b e h a v i o u r o f t h e h e r d .  Certain  recognized r e l a t i o n s h i p s  and f o r a g e q u a l i t y and q u a n t i t y . are  highly  selective  A r n o l d and D u d z i n s k i  for  both  exist It  between an a n i m a l ' s i s widely  specific  (1978) summarized t h a t 79  foraging  reported that  plants  and  behaviour  grazing  specific  plant  \"from t h e s i n g l e p l a n t ,  animals parts.  sheep and  \u000Cc a t t l e eat l e a f  i n p r e f e r e n c e t o stem (Cook and H a r r i s ,  A r n o l d , 1960b, 1 9 6 4 a ) , green ( o r young) m a t e r i a l (Stapleton,  1934; M i t t o n ,  1953; Cook e t  1950; R e p p e r t ,  1960;  i n p r e f e r e n c e t o dry ( o r o l d )  al_. 1950; C o l i s h a w  and A l d e r ,  1960;  R e p p e r t , 1960; and A r n o l d , 1 9 6 4 a ) \" .  The degree o f s e l e c t i v i t y intake rates.  e x p r e s s e d by an animal  A r n o l d and D u d z i n s k i  were r e l a t e d t o \" . . . y i e l d s  l e a v e s per u n i t  as f o r a g e m a t u r e s ,  h e r b i v o r e s are  often c l o s e l y  green and dry p a s t u r e ,  a r e a and d i e t particularly  selective  for  t h e d e t r i m e n t o f i n t a k e r a t e s ( A r n o l d and D u d z i n s k i  slightly  more d e t a i l ,  White  and T r u d e l l  to  rates  length  digestibility\".  of  Generally,  new r a t h e r  o l d growth (Meyer e t a]_. 1957, A r n o l d 1 9 6 0 b ) , but t h i s s e l e c t i v i t y  In  related  (1978) s t a t e d t h a t f o r sheep, i n t a k e  per u n i t area o f  p a s t u r e , number o f  is  than  i s often to  1978).  (1980)  summarized t h e  extrinsic  f a c t o r s l i m i t i n g f o r a g e i n t a k e r a t e s i n c a r i b o u and r e i n d e e r as b e i n g : a) food a v a i l a b i l i t y - biomass - p r o t e c t i o n by snow - p r o t e c t i o n by dead p l a n t  material  b) food q u a l i t y - low dry m a t t e r d i g e s t i b i l i t y due to -  low  dry  hibitors  matter (e.g.  digestibilities  fibrousness  due  to  tannins)  - t o x i c p l a n t compounds c) harassment - by i n s e c t s and p r e d a t i o n d) b e h a v i o u r a l  interactions during -  calving  -  rutting  - resource  80  competition  digestive  in-  \u000CThat  grazing  decreasing  times  intake  researchers.  generally rates  feed,  it  has  Allden et a K  imposed l i m i t a t i o n s  increase been  with  decreasing  documented  by  a  pasture  much  quality  larger  of  (1970) s t a t e d t h a t \"when a c c e s s i b i l i t y o f herbage  on t h e r a t e a t which t h e animal was a b l e t o  was shown t h a t  number  and  the  sheep was a b l e  partially  prehend  t o compensate  for  its the  reduced amount o f herbage p r e s e n t by an i n c r e a s e i n g r a z i n g time (from 6 t o 13 hrs/day)\".  Similarly,  Sheppard e t a]_. reported  an  Arnold  (1960;  sheep),  Hancock  (1957; b e e f c a t t l e ) , and Waite e t a]_.  increase  in  grazing  time  q u a n t i t y , q u a l i t y and/or p a l a t a b i l i t y .  for  (1954;  dairy  (1951; d a i r y c a t t l e )  animals  with  decreasing  bouts  with  decreasing  a  forage  As p r e v i o u s l y  r e p o r t e d on t h e i n c r e a s i n g d u r a t i o n o f  daylength,  all  Such t r e n d s g e n e r a l l y meant l o n g e r but  l e s s f r e q u e n t f o r a g i n g bouts w i t h d e c l i n i n g p a s t u r e c o n d i t i o n s . d i s c u s s e d , A r n o l d and D u d z i n s k i  cattle),  trend  likely  associated  with  similar  seasonal  activity  periods  grazing  declining  p a s t u r e c o n d i t i o n s more so than d a y l e n g t h .  Some  studies  trends.  on  less  domestic  species  F o r example,  Thompson  (1970)  have  shown  showed t h a t  diurnal of  r e i n d e e r decreased i n l e n g t h and i n c r e a s e d i n f r e q u e n c y from w i n t e r t o months,  although  similar  results  that  he for  presents the  no  central  interpretation Arctic  increased forage a v a i l a b i l i t y  required to f i l l rumen t u r n o v e r  caribou  for  this  herd,  trend.  Roby  suggested the  time  reduce  times\".  a detailed interpretation  herd's  has been d e v e l o p e d .  seasonal  diurnal  patterns  t h e change from t h e c y c l i c of  (1978)  would be expected t o  Based on t h e above r e l a t i o n s h i p s ,  bedding)  spring  Reporting  i n t h e summer months \" . . . r e d u c e s  t h e rumen and i n c r e a s e d q u a l i t y  wild  the  herd's  nature  activity  (i.e. pattern  81  successive in  spring  It  o f changes i n t h e is  intervals and  postulated of  feeding  summer t o  the  that and more  \u000Ccontinuous forage  foraging  behaviour  conditions.  As  of  the  discussed  fall  in  was  Section  closely C  of  related  Results,  to  declining  many  preferred  d i e t a r y s p e c i e s o f g r a s s e s , s h r u b s , and f o r b s were abundant i n t h e s p r i n g and summer and i n a r a p i d growth phase. species  of  forbs  (e.g.  In a d d i t i o n , t h e l e a v e s o f many p r e f e r r e d  Balsamoriza  sagittata  r e l a t i v e l y l a r g e and s u c c u l e n t and t h e t i l l e r relatively animal has  long,  a condition  conducive  ( A l l d e n and W h i t t a k e r 1 9 7 0 ) .  been  shown  to  be  high  in  Lupinus  sericeus)  were  l e n g t h s o f u t i l i z e d g r a s s e s were large  bite  Since forage  crude  1973), the c a p t i v e animals l i k e l y  to  and  protein  sizes  in this  and  in  the  grazing  phenological  highly  digestible  had r a p i d i n t a k e and a s s i m i l a t i o n  state (Hebert  rates,  in  s p i t e o f t h e h i g h degree o f s p e c i e s s e l e c t i v i t y which t h e y demonstrated d u r i n g the period  (Pitt  and Wikeem 1 9 7 9 ) .  Considering that the  rate of  i n g e s t a v a r i e s d i r e c t l y w i t h i t s i n t a k e r a t e and d i g e s t i b i l i t y 1961),  the  turnover  high.  This  rapid  rate  for  turnover  the  rate  ingested  would  forage  was,  have enabled t h e  rumens and then r u m i n a t e , s e v e r a l t i m e s d u r i n g d a y l i g h t  passage  of  (Blaxter et a l .  therefore, sheep t o  probably  fill  in the c y c l i c  their fashion  demonstrated.  The  change  from  bedding-ruminating fall  partially  captive  cyclic  periods  resulted  frequently  from t h e  forage at s l i g h t l y whole t o high l e v e l  fluctuate  out  more c o n t i n u o u s l y  of  successive  of  increasingly of  separate  visual  range  foraging  dispersed  of  each  less  drastically, throughout  patterns as t h e  t h e day.  demonstrated fall  and t o  months  that  the  distribution  of  the  other,  That  is,  different  began t o  bed  and  graphs f o r t h e herd as a a relatively  However,  analysis  animals  and  in  indicate  progressed  82  feeding  behaviour  subgroups.  d i f f e r e n t times, causing a c t i v i t y  of a c t i v i t y  activity  pattern  t o t h e more c o n t i n u o u s  herd and t h e asynchrony  subgroups  animal  this  were,  and t h a t  in the  of  constant, individual  fact,  foraging  herd  activity  \u000Cgraphs  were  conversion season  not  to  misrepresenting  continuous  maturation  and  daylight  fall  declining availability  the  herd's  activity  regrowth  of  true  behaviour.  seemed t o  the  study  This  gradual  c o i n c i d e with the  site's  vegetation.  o f f o r a g e from shrubs and ephemeral  the they  animals were  demonstrated  selective  regrowth  on  regrowth,  often  accessible required  the  reduced  for  plant  grasses  species  parts,  utilized  shrouded by l e s s  o r as abundant  a considerable  a  (Wikeem,  palatable,  of  (Wikeem p e r s .  selectivity  showing  as p r e f e r r e d degree  site  pers.  foraging  in  effort  in bite size  reduced i n t a k e  most o f t h e day w i t h o u t bedding-ruminating increasingly  rates,  repeatedly  periods.  Is  to  fall  However,  this  was  procure  is  their  further  more pronounced d u r i n g t h e  months  as  likely It  is  and a r e d u c t i o n throughout  rumens and w i t h o u t  suggested t h a t  fall  not  it.  e n a b l i n g the animals t o forage filling  months,  months and  selectivity  While  for  parts,  previous  postulated t h a t the time required t o express t h i s  previous  preference  plant  utilize  comm.).  comm.)  apical  forage  from  strong  The  f o r b s p r e f e r r e d by  t h e herd d u r i n g t h e s p r i n g and summer appeared t o f o r c e t h e a n i m a l s t o t h e more common g r a s s s p e c i e s o f t h e study  late  this  because  frequent  trend  became  regrowth  became  l e s s a v a i l a b l e and i n t a k e r a t e s f u r t h e r d e c l i n e d .  The absence o f high l e v e l s o f a c t i v i t y t h r o u g h o u t t h e day d u r i n g t h e period  of  December  temperatures,  as  appeared,  previously  in  part,  to  discussed.  be  the  However,  inclement  consequence  the  bedding  of  low  period  at  m i d - d a y , when t e m p e r a t u r e s approached t h e d a i l y maximum, may have r e f l e c t e d a need t o r u m i n a t e . the  rumination  However,  it  is  consumed  by  the  remaining  It  is  period, possible herd  unlikely  t h a t an i n c r e a s e  considering that  may  the  a decrease  have  been  regrowth and t h e sheep,  a  snow in  factor.  although  83  the  in  intake  accumulation  at  digestibility The  cratering  deep to  rates  of  snow  prompted  that  time.  the  forage  covered  some e x t e n t ,  any  seemed  \u000Cc o n t e n t t o f e e d l a r g e l y on stems and seed heads o f bluebunch wheatgrass and on browse s p e c i e s which were above t h e snow. digestible ruminate  and after  explanation  slowly  processed,  short  for  the  foraging mid-day  This high f i b r e  would  have  periods.  \"siesta\"  forced  Hoefs  observed  the  (1974)  in  forage, being  his  herd  to  offered  captive  less  bed a  and  similar  Dall's  sheep  herd.  Once t h e snow c o v e r d i s a p p e a r e d from study s i t e , t h e sheep r e v e r t e d back t o a more c o n t i n u o u s f o r a g i n g b e h a v i o u r .  The a n i m a l s were observed f e e d i n g low t o  the  most  ground,  possibly  again.  It  is  intakes  rates  selecting  postulated were  the  that,  recent  similar  sufficiently  low  to to  growth  late  fall  enable  of  the  plants  foraging  the  once  conditions,  animals  to  forage  c o n t i n u o u s l y t h r o u g h o u t t h e d a y l i g h t hours w i t h o u t r e s t i n g t o r u m i n a t e .  The  activity  patterns  demonstrated  by  the  i n f l u e n c e d by t h e presence o f supplemental most, i f  January  were  naturally  From dawn t o l a t e morning,  could  depleted.  activities  of  By f o r a g i n g at such an e a s i l y e x p l o i t e d , p o i n t food r e s o u r c e , each fill  e n a b l i n g t h e animal was  feed.  in  not a l l , o f t h e c a p t i v e a n i m a l s were c o n c e n t r a t e d i n t h e v i c i n i t y  t h i s feed. animal  herd  its  rumen  and  process  the  ingesta  t o f e e d and ruminate two o r t h r e e  Because  the  herd  members  around t h e f e e d supplement, l i k e l y  were  not  relatively  quickly,  times before the synchronous  because o f t h e l i m i t e d  in  hay  their  foraging  s p a c e , t h e a c t i v i t y graph ( F i g . 1) i n d i c a t e s an a v o i d a n c e o f t h e e a r l y morning hours by t h e a n i m a l s f o r J a n u a r y .  Such b e h a v i o u r was not a p p a r e n t , as i t was  d u r i n g t h e i n c l e m e n t c o l d weather p e r i o d o f December, p r o b a b l y because o f t h e easy  and  energetically  efficient  foraging  pile.  84  conditions  afforded  by  the  hay  \u000CSince hay was  provided at a rate of only 45 kg/day, t h i s supplemental  source was depleted by late morning.  Consequently, the animals were forced to  u t i l i z e the study areas native vegetation during the afternoon. vegetation  on the lower half of the enclosure were snow free  January's  latter  areas.  By  common  grass  half  primarily species  and  the  animals  selecting the (Agropyron  food  restricted  fall  regrowth  spicatum,  their  Clumps of for much of  foraging  to  these  at the base of the more  Koeleria  cristata)  (pers.  obs.;  Wikeem, pers. comm.), i t i s postulated that the animals again had s u f f i c i e n t l y low intake rates to reduce the rate of rumen f i l l the need f o r inactive ruminating periods.  and, consequently, eliminate  As a r e s u l t , the majority of the  animals did not bed u n t i l n i g h t f a l l , when temperatures again began to drop.  In  February, warmer mean-daily  study  site's  lower  elevations  temperatures provided  and  the  the  animals  loss  of snow from  with  similar  the  foraging  conditions to those experienced in November and the mild periods in December. Still  selecting the f a l l  regrowth  of the study s i t e ' s  obs.;  Wikeem, pers. comm.), the herd  not  surprisingly  common grasses (pers. demonstrated  similar  daily a c t i v i t y patterns to those months.  During March, the new growth of spring offered a highly nutritious food source to  the animals.  However, i n i t s i n i t i a l  development, t h i s  growth was  not  abundant, being homogeneously but l i g h t l y dispersed over the lower half of the study s i t e .  In the grasses and forbs, growth occurred low to the ground  s i m i l a r to f a l l parts growth  or  litter.  regrowth, was As  often shrouded  previously  pattern of feeding and winter months.  by less palatable, cured plant  discussed, the  (Wikeem, pers. comm.) and demonstrated  animals  selected  a more c y c l i c and  this  85  new  synchronous  bedding-ruminating periods than in previous f a l l  It i s postulated that the new  and,  and  growth enabled the animals to  \u000Cincrease t h e i r of  the  herd's  summer.  forage  i n t a k e and a s s i m i l a t i o n  cyclic  Activity  activity  which  peaks were, however,  s p r i n g and summer months, sufficiently  pattern  dispersed  inaccessible  and l e s s  the  to  resulting  predominated  longer  suggesting that  or  rates,  in  the  frequent  low d e n s i t y  keep  i n the  intake  return  spring than  and  in  the  s p r i n g growth was  rates  below  maximum  levels.  The  additional  although  activity  limited  in  data  collected  quantity,  further  q u a l i t y and q u a n t i t y on t h e h e r d ' s the  herd,  under  synchronous periods. similar  seasonable  activity Other  pattern  researchers  in  demonstrated  diurnal  weather of  November  the  behaviour.  conditions,  successive  observing  and  demonstrated  herd  and  during  b e h a v i o u r f o r t h e herd (D. Eastman, A. B o t t r e l l ,  site.  1977 and appeared t o  be  related  to  forage  of  a  1978,  cyclic,  bedding-ruminating November  reported This  l e v e l s observed  condition  on t h e  in  study  The summer and f a l l months o f 1978 were r e l a t i v e l y wet f o r t h e Okanagan  r e g i o n and, c o n s e q u e n t l y , many o f t h e e n c l o s u r e ' s major p l a n t s p e c i e s i n a high q u a l i t y , (Wikeem,  pers.  growing  season,  reduction), accessible  vegetative state until  comm.).  It  coupled  resulted forage  in  being  is  with large  a  f a s h i o n more t y p i c a l  On December was  by  this  reduced  quantities  of  even  in  herd  highly  November  their  unusually size  in  productive 1978  nutritious,  (Wikeem,  (40%  readily  pers.  comm.),  rumens and ruminate i n a c y c l i c  o f s p r i n g and summer p e r i o d s .  13, 1978, green f a l l  covered  that  vastly  available  remained  t h e c o l d e r , d r i e r weather o f October  postulated  a l l o w i n g the animals t o repeatedly f i l l  but  forage  p e r s . comm.).  p a t t e r n was c o m p l e t e l y u n l i k e t h e more c o n t i n u o u s a c t i v i t y November  effects  1978,  On November 14,  feeding  the  December,  regrowth was s t i l l  a 15 cm c o v e r  of  86  powder  snow.  a v a i l a b l e t o the Unlike  their  animals  behaviour  \u000Cduring s i m i l a r  foraging conditions  appear t o u t i l i z e chose  instead  i n e a r l y December,  1977, t h e sheep d i d not  seed heads and browse s p e c i e s p r o t r u d i n g above t h e snow but of  this  e n e r g e t i c a l l y more c o s t l y f o r a g i n g s t r a t e g y was p o s s i b l y a r e f l e c t i o n o f  their  improved  crater  physiological  abundance efforts  to  of  fall  to  the  condition  regrowth  regrowth.  over  that  or both.  It  is  slowed i n t a k e r a t e s s u f f i c i e n t l y  continuous  fashion  throughout  the  of  Their  December  postulated  selection  1977 o r that  the  their  greater cratering  t o a l l o w the animals to forage  day,  unlike  the  comparable  in a  period  in  December 1977 when a mid-day b e d d i n g - r u m i n a t i o n p e r i o d was r e q u i r e d .  S e v e r a l s t u d i e s have p r e s e n t e d d a t a on t h e a c t i v i t y p a t t e r n s o f mountain sheep but  few make d e t a i l e d  spring  and  summer  seasonal  months,  comparisons  most  studied  or  interpretations.  bighorn  During  populations  showed  the  fewer  a c t i v i t y peaks than our c a p t i v e h e r d , a l t h o u g h a c t i v e p e r i o d s at dawn and l a t e a f t e r n o o n , as p r e v i o u s l y d i s c u s s e d , were i n v a r i a b l y p r e s e n t . Davis  (1938)  both found t h r e e  peaks  of  activity  for  Mills  (1937) and  a Yellowstone  National  Park p o p u l a t i o n , o c c u r r i n g a t dawn, mid-day and i n t h e l a t e a f t e r n o o n . and T a y l o r  (1939)  found  a bimodal  activity  pattern  in  Texas  bighorns  f o r a g i n g peaks e x t e n d i n g throughout t h e morning and l a t e a f t e r n o o n . r e s t period occurred at mid-day.  Davis with  A single  Van Dyke (1978) found e a r l y morning and l a t e  a f t e r n o o n t o be t h e o n l y c o n s i s t e n t p e r i o d s o f a c t i v i t y f o r Oregon b i g h o r n s .  R e p o r t s on t h e f a l l  a c t i v i t y p a t t e r n s o f w i l d sheep more c l o s e l y resemble 1978  r a t h e r than 1977 d a t a f o r t h e c a p t i v e h e r d .  Geist  (1971) found an average  of  f o u r a c t i v i t y peaks f o r S t o n e ' s sheep rams i n O c t o b e r , w i t h one major bedding period  at  found  that  period  mid-day which a captive  during  the  fall  involved  Dall's  almost  sheep  (except  all  ram a l s o  during  87  the  visible  animals.  demonstrated rut),  with  Hoefs  a mid-day  three  or  four  (1974) bedding active  \u000Cperiods during d a y l i g h t .  Van Dyke (1978) a g a i n n o t i c e d o n l y e a r l y morning and  l a t e e v e n i n g a c t i v i t y p e a k s , w i t h an e x t e n s i v e mid-day r e s t i n g p e r i o d .  Researchers  have  reported  d u r i n g w i n t e r months. Geist  (1971)  activity  noted  peak  variable  peak a t d u s k .  pattern  for  wild  sheep  S i m i l a r t o t h e i n c l e m e n t weather p e r i o d o f t h i s  that  Stone's  occurring at  presented s i m i l a r  activity  results  sheep  fed  noon and a g a i n  for California  little in  in  late  the  morning,  afternoon.  herds study,  with  Blood  b i g h o r n s but showed a t h i r d  an  (1963) activity  However, Hoefs (1974) and Van Dyke (1978) found no a v o i d a n c e o f  t h e morning hours by mountain sheep i n t h e i r s t u d i e s . major a c t i v i t y  peak  in  early  morning and l a t e  I n s t e a d , sheep showed a  afternoon,  with  an  extensive  mid-day r e s t p e r i o d .  Since  results  from t h i s  t o the diurnal  behaviour  above a r e d i f f i c u l t each s i t e . captive  study  to  of  in  sheep, t h e  interpret  The r e l a t i v e l y  herd  have i n d i c a t e d t h e importance  spring  between-site  without  and summer,  for  example,  conditions  discrepancies  more d e t a i l e d  l a r g e number o f a c t i v i t y  range  range  discussed  information  on  peaks demonstrated by t h e may s i m p l y  reflect  a more  c o n c e n t r a t e d , r e a d i l y a v a i l a b l e food r e s o u r c e on t h e study s i t e than on o t h e r , natural  r a n g e s , a l l o w i n g f o r more r a p i d rumen f i l l .  Differences  o f study areas may have a l s o caused t h e d i s c r e p a n c i e s studies. less would  have  within  obscured  a herd than  the  did  our  more m u l t i - p e a k e d  captive activity  p a r t i c u l a r l y w i t h o u t a n i m a l s equipped w i t h i d e n t i t y  Nocturnal  Although  between t h i s  Animals o c c u p y i n g a l a r g e r , more rugged n a t u r a l  synchrony  i n the  and o t h e r  range l i k e l y  sheep.  This  pattern  of  size  showed  asynchrony individuals,  collars.  activity  limited  activity  d a t a were c o l l e c t e d 88  during the  hours  of  darkness,  \u000Ccertain  characteristics  t o be o f p r a c t i c a l Results,  night  of t h i s  nocturnal  and b i o e n e r g e t i c s i g n i f i c a n c e .  foraging  during daylight hours.  bouts were not  behaviour  may  possess r e l a t i v e l y some n o c t u r n a l  As p r e v i o u s l y d i s c u s s e d  as f r e q u e n t  nor  as  have  some  immediate  survivial  good n i g h t v i s i o n , i t  predators.  vicinity  minimized  if  value.  their  predation.  diurnal  patterns  possible.  Almost  to  the  the  T h i s may f u n c t i o n t o f i l l  daylight  period,  the h o t t e r p o r t i o n s  in  those  Although  bedding a r e a .  sheep  foraging  bouts  that  invariably,  without  their  their  sheep  areas  discomfort  of  near  sheep have  night  their  Such a s t r a t e g y w o u l d ,  is most  period of the  greatest  that  also  activity  demonstrate  rumens t o t h e i r  t h e thermal  o f t h e day.  obviously  o f b e i n g s i n g l e d out  I t would appear t h a t ensure  to  extensive f o r a g i n g period l a t e i n the day, i n the s p r i n g t o f a l l year.  as  i s l i k e l y not as developed as t h a t  By l i m i t i n g  and a t t a c k e d by a p o t e n t i a l their  lengthy  of  o t h e r f e e d i n g o r bedding a n i m a l s , sheep reduced t h e r i s k  modified  and seemed  They u s u a l l y i n v o l v e d l e s s than 50% o f t h e herd at any  one t i m e and were r e s t r i c t e d t o t h e This  b e h a v i o u r were apparent  capacity  would o c c u r in turn,  of  during  reduce  the  stimulus to forage during the night.  The apparent  decrease  in  w i n t e r months was l i k e l y avoidance  of  suboptimal  conditions  than  simply  early  bedding  nocturnal  activity  by t h e  morning probably  hours.  Foraging  results  and c o n s e r v i n g  in  heat,  dispersed  detail. at  Geist  nightfall,  the  colder their  thermally  and  visually  negative  energy  balance  particularly  if  good v i s i b i l t y  is  forage s e l e c t i o n .  (1971) with  in  a greater  Other a u t h o r s have r e p o r t e d on t h e n o c t u r n a l little  during  an energy c o n s e r v i n g s t r a t e g y , c o n s i s t e n t w i t h  r e q u i r e d by sheep f o r e f f i c i e n t  in  sheep  reported  sufficiently  89  b e h a v i o u r o f mountain sheep but  that  sheep  developed  are night  active vision  and  widely  to  enable  \u000Cthem t o r e t i r e t o rugged c l i f f  terrain  during darkness.  Woolf et al_.  (1970)  n o t i c e d f e e d i n g a t i n t e r v a l s throughout t h e n i g h t but suggested t h a t movements were  \"limited  to  the  immediate  vicinity  of  the  bedground\".  Van Dyke  also  r e p o r t e d some n i g h t movements i n b i g h o r n s .  A  further  discussion  on  the  possible  seasonal  trends  in  the  nocturnal  b e h a v i o u r o f t h e c a p t i v e herd appears i n S e c t i o n C2.  2.  Seasonal a c t i v i t y  As p r e v i o u s l y  discussed,  budgets  research,  on d o m e s t i c  animals  r e l a t i o n s h i p between p a s t u r e q u a l i t y and g r a z i n g t i m e s Arnold 1960a).  Such a t r e n d was not obvious  daily activity  budgets.  has shown an  inverse  (Sheppard e t ail_. 1957,  f o r t h e c a p t i v e herd from t h e i r  A l t h o u g h t h e a n i m a l s devoted a g r e a t e r p r o p o r t i o n  of  t h e day t o f o r a g i n g as p a s t u r e c o n d i t i o n s d e c l i n e d , t h e y were s i m p l y unable t o substantially daylengths.  increase  their  daylight  Research has shown t h a t  foraging  times  bighorns maintain  i n t a k e l e v e l s o v e r a 24 hr p e r i o d d u r i n g t h e e a r l y Chappel 1 9 7 8 ) , at l e a s t u n t i l 1973). the f a l l assumed nutrient  Considering that  the  Wikeem ( p e r s .  intake  captive levels,  comm.)  herd likely  was as  attempting a  were s u f f i c i e n t  it  is  doubtful  rates  months  found crude  high  total  (Hebert  1973,  h y p o t h e s i z e d t h a t t h e herd i n c r e a s e d i t s  protein  exceed t h i s to  maintain  for  that the diurnal  t o p r o v i d e adequate n u t r i t i o n a l  d e c r e a s e d , and t h a t t o t a l  shortening  relatively  fall  prewintering  However, w i t h t h e proposed reduced i n t a k e (see S e c t i o n C I ) ,  of  crude p r o t e i n l e v e l s drop below 7 t o 8% (Hebert  regrowth o f u t i l i z e d g r a s s e s t o e a s i l y that  because  this  it  of  can be  relatively  fattening  high  requirement.  period of  grazing times  levels.  nocturnal  value,  levels  the  year  of the  herd  Consequently,  it  is  g r a z i n g t i m e s as d a y l e n g t h  g r a z i n g t i m e f o r t h e herd o v e r a 24 hr p e r i o d peaked  90  \u000Cin the e a r l y f a l l  (September, October) months.  A secondary peak may a l s o have  o c c u r r e d i n s p r i n g (March) w i t h t h e onset o f body growth and, t o a secondary d e g r e e , r e p r o d u c t i v e demands. of  increasing  nocturnal  A r n o l d and D u d z i n s k i  activity  for  cattle  p r o p o r t i o n o f n i g h t g r a z i n g was s i g n i f i c a n t l y ve),  daylength  important\".  (A  ve)  and  similar  latitude  (-  relationship  ( A r n o l d and D u d z i n s k i 1978, F i g .  (1978) noted such a t r e n d  and  suggested  related to total  ve),  with  appears  to  ..\"the  g r a z i n g time (+  daylength exist  that  being  for  the  most  domestic  sheep  1.2)  Based on t h e d i u r n a l and l i m i t e d n o c t u r n a l d a t a c o l l e c t e d on t h e study a n i m a l s d u r i n g December and J a n u a r y , foraging  times  for  the  it  was apparent  complete  24  hr  that  period  this  with  trend  of  decreasing  increasing  daylight  was  d i s r u p t e d d u r i n g t h e w i n t e r months, when t h e herd reduced t h e i r f o r a g i n g t i m e s and  efforts  activity  in  (i.e.  proportion  bighorns,  suggested by G e i s t  of  day)  reportedly  (1971)  considerably.  an  energy  and Chappel  (1978)  m e t a b o l i c and i n t a k e r a t e s  (Chappel  r e p o r t e d t h a t supplemental  feed g e n e r a l l y  animals, both  it  the  above.  is  probable that January's  supplement  food  source  conserving and i s  reduced  strategy,  has  associated with  reduced t h e g r a z i n g t i m e o f  and t h e  reduced  v a l u e was t h e  winter  activity  been  reduced  S i n c e A r n o l d and D u d z i n s k i  low f o r a g i n g  winter  (1978) pasture  result  of  suggested  Reduced n o c t u r n a l a c t i v i t y d u r i n g t h e w i n t e r has a l s o been documented,  a l t h o u g h not s p e c i f i c a l l y penned  1978).  Such  white-tailed  deer,  for bighorns. reported  two  Ozoga and Verme ( 1 9 7 0 ) , i n s t u d i e s on nocturnal  activity  peaks  winter,  but a d e c l i n e i n n i g h t a c t i v i t y  as t h e w i n t e r p r o g r e s s e d .  et _al_.  (1973) found t h a t e l k  fed l e s s  \"actually  t h e w i n t e r than summer\", w i t h a n i m a l s s p e n d i n g long winter night  bedded...\".  91  in  Craighead  per hour o f darkness ...\"most  of  early  during  t h e hours o f  the  \u000CBoth observed and suggested t r e n d s  for  times  researchers  have been r e p o r t e d by o t h e r  (1978)  found b i g h o r n d a y l i g h t  the  herd's  foraging e f f o r t  t o i n c r e a s e from summer t o w i n t e r .  daily  of wild (i.e.  grazing e f f o r t s ungulates.  proportion  Van Dyke  of  daylength)  He a t t r i b u t e d t h i s t r e n d t o :  a)  l e s s d a y l i g h t hours a v a i l a b l e i n which t o be a c t i v e i n w i n t e r ;  b)  poorer f o r a g e q u a l i t y i n w i n t e r ;  c)  less a v a i l a b l e forage in w i n t e r ;  d)  colder  temperatures  and  i n w i n t e r which causes  an i n c r e a s e  in  energy  demands.  (In  light  of  Chappel's  (1978)  findings  on  the  thermal  neutral  zone  of  b i g h o r n s , t h i s l a s t p o s t u l a t i o n seems somewhat q u e s t i o n a b l e ) .  C r a i g h e a d et  a]_. ( 1 9 7 3 ) , i n t h e i r  N a t i o n a l P a r k , found t o t a l spring,  with  particularly  considerably  elk  reduced  times  being  evident  times  on  of forage.  a  daily  basis  seemed  largely  in  and  summer  December 1977, when ground a c c u m u l a t i o n s  a]_.  (1973)  dependent  The c a p t i v e h e r d , as p r e v i o u s l y d i s c u s s e d ,  o f l a t e December 1977 t h a n d u r i n g t h e more d i f f i c u l t  et  Yellowstone  and  regime o f t h e study a n i m a l s , t h e degree o f  c o n s i d e r a b l y more d a y l i g h t time t o f o r a g i n g d u r i n g t h e m i l d ,  Craighead  in  in winter.  foraging  accessibility  radio-collared  f e e d i n g t i m e s o v e r 24 hr p e r i o d s peaked i n f a l l  W i t h i n t h e reduced w i n t e r a c t i v i t y winter  study o f  attributed  of  low  92  foraging, period of  times  in  the  devoted  snow-free  snow reached 30 cm. foraging  on  period early  Similarly,  winter  to  a  \u000C\" s c a r c i t y of palatable food, t r a v e l need t o c o n s e r v e e n e r g y \" .  restrictions  imposed by deep snow, and t h e  Roby (1978) o f f e r e d an o p p o s i n g view on t h e impacts  o f snow c o v e r , s u g g e s t i n g t h a t f o r a g i n g e f f o r t s were g r e a t e s t when snow depths and c r a t e r i n g r e q u i r e m e n t s were g r e a t e s t .  S i n c e t h e c a p t i v e sheep g e n e r a l l y ruminated i n a prone p o s i t i o n , bedding t i m e s f o r t h e herd were l a r g e l y Consequently, 0.92),  a function  l o w e r and f o r a g i n g  pronounced  in  than  activity  in  spring  rather  winter  than  at  any  correlated  high.  was  than  o v e r a 24 h r p e r i o d ,  likely  higher total  other  to  be t h e  bedding  study Van Dyke (1978)  reciprocal  times  over  summer and f a l l ,  a  of  feeding  24  hr  time  generally  to  be  categories  proved t o  in  such  rates  were  when i n t a k e  rates  the  the  result  of  rates.  of  the  year  less herd's  It  can  because  be have  of  the  night.  found d i u r n a l  Craighead relatively  is  of  be t o o l o n g t o  limited provide  value.  accurate  such s h o r t term e v e n t s as s t a n d i n g , t r a v e l l i n g activities  (r =  et  bedding  al_.  effort  (1973),  consistent  in  found spring,  and h i g h i n w i n t e r .  behavioural  interval  intake  peak,  A d e t a i l e d i n t e r p r e t a t i o n o f t h e seasonal f l u c t u a t i o n s other  daylength  bedding t i m e s would l i k e l y  effort.  period  to  requirements.  The m i d - w i n t e r  intake  l i m i t e d nocturnal a c t i v i t y during the long winter  Similar to t h i s  rumination  s p r i n g and f a l l  effort  and summer,  levels,  speculated that, higher  herd's  summer when f o r a g e  h i g h and d r o p p i n g i n t h e e a r l y  were presumably  reduced  the  bedding t i m e s were s i g n i f i c a n t l y  peaking i n t h e s p r i n g and e a r l y  presumably  been  of  (nursing,  behavioural  interacting, categories  example, t h e r e l a t i v e l y  playing). were  i n t i m e s devoted t o t h e A  15  activity  (walking,  and  can  budget  sampling data  running) and  However c e r t a i n  apparent  minute  be  seasonal discussed.  on  \"other\" trends For  h i g h p r o p o r t i o n o f t i m e devoted t o s t a n d i n g d u r i n g t h e 93  \u000Cc o l d e s t months appeared t o r e f l e c t low t e m p e r a t u r e s .  Both G e i s t  a behavioural  (1971) and Chappel  (1978) r e p o r t e d t h a t  f r e q u e n t l y stood i n a \"closed standing posture\" temperatures, offers  rather  equivalent  circumstances. occurred  than  or  large  litter  was a v a i l a b l e  canopy  likely  January  bed  requiring  a period  these s i t e s .  or  sites  losses  the  lower  (Major t r e k s  of  of  were  a  day,  the  in  certain  captive  and where  wave was  the  largely  on  many  considerable  the  where  only  occasions,  distance  frequently  the three  animals  from  chose  in  to  one  o r bed on u n i n s u l a t e d  animals  tree  However,  confined  site,  herd  accumulated  radiation.  study  t o and from t h e p r e f e r r e d bed s i t e s  o c c a s i o n a l l y at m i d - d a y ) .  for  posture  material  t o such a s i t e  the  bedding,  cold  a  where  Consequently,  rumination  period  long  such  ponderosa),  bedding  third  than  bed s i t e s  (Pinus  to  that  to  bighorns  1978) t o combat  speculated  foraging  occurred.  Rather than t r a v e l active  winter  pines  February,  be  (Chappel  conservation  preferred  heat  of  can  an i n s u l a t i v e  and  feed  preferred  the  as  It  energy  Ponderosa  reduced  supplemental  during  greater  Generally,  under  December,  bed.  a d a p t a t i o n o f t h e animals  of  ground  to  stand.  d i d o c c u r a t dawn, dusk  I t i s p o s s i b l e t h a t c o n v e c t i v e heat l o s s e s i n  and such  a p o s i t i o n c o n s t i t u t e d l e s s o f an energy d r a i n f o r s h o r t p e r i o d s than w a l k i n g t o p r e f e r r e d s i t e s o r bedding on u n i n s u l a t e d ground.  The r e l a t i v e l y general  h i g h p r o p o r t i o n o f t i m e devoted t o t r a v e l  high l e v e l  of  \"flighty\"  in April  b e h a v i o u r f o r t h e herd i n t h a t  reflected a month.  herd f r e q u e n t l y made l o n g t r e k s between f o r a g i n g bouts and \" p a n i c \" f l i g h t s no apparent levels,  reason.  during  interpret,  the  such  return of optimal  This early  flighty  behaviour  continued  development behaviour  of  that  seemed t o  foraging conditions,  94  into  May, a l t h o u g h a t  year's occur  lambs.  indicating a possible  for  reduced  Difficult  simultaneously  The  with  relationship  to the to  \u000Cincreasing energized May.  available play  bouts  The h i g h  opposing  energy.  The  seemed t o  prompt  travel  proportions  distributions  invariably  chose  of  areas  presence  adjacent  December and  to  than  0.5  observations  km  of  to  the  travelling  with  water  their  continue  appeared t o  bedding  the  periods, while preferred feeding s i t e s more  lambs  such b e h a v i o u r t o  in  feeding  of  paddock  throughout  result  sites.  from  This  resulted  animals,  particularly  in in  almost  major  bedding  for  occurred  relatively the  the  Animals  o f reduced snow a c c u m u l a t i o n s  south.  highly  frequent  morning  and  late  evening.  The r e l a t i v e l y h i g h p r o p o r t i o n o f d a y l i g h t t i m e s devoted t o \" o t h e r \" by t h e  herd appeared  t h e i r lambs. contributor  related  to  the  maternal  interactions  to t h i s  activity  \"other\" a c t i v i t y  category.  initiated  devoted t o t h i s c a t e g o r y .  Interactions  by t h e  lambs,  and  It  appeared t h a t  o f t h e young rams i n t r o d u c e d f o r t h e to  generally  Daily v a r i a b i l i t y  consumed t h e  bouts  amongst  remaining  r e f l e c t e d the quiescent  few ewes became s e x u a l l y  1977, e i t h e r because o f t h e i r poor p h y s i o l o g i c a l  techniques  and p l a y  time  That r u t t i n g a c t i v i t i e s d i d not produce a secondary  peak i n November a c c u r a t e l y  period of the herd.  activities,  between ewes  N u r s i n g , which peaked i n May and e a r l y J u n e , was t h e predominant  t h e ewes, but g e n e r a l l y  sampling  activities  this  one  rut.  have  c o n d i t i o n or the  Other  reported  studies on  a  rutting  receptive  inexperience  using s i m i l a r  fall  peak  in  in  scan  \"other\"  r e l a t e d t o t h e r u t (Roby 1978, Van Dyke 1 9 7 8 ) .  i n herd b e h a v i o u r  The day t o day v a r i a b i l i t y  i n t h e h e r d ' s b e h a v i o u r was a s i g n i f i c a n t source o f  v a r i a t i o n i n t h e l i n e a r model used t o a n a l y z e herd b e h a v i o u r i n a l l months but  95  \u000CJanuary.  With  evidence  to  patterns  suggest  (i.e.  temperatures, changes  the  in  exception that  mean  of  such daily  were  However,  pressure,  variation  the  in  at  least  captive  was  temperatures,  wind  December, result  daily  of  relative  responsible work  in  was  gross  weather  and  minimum  for  this  factors  humidity  ( A r n o l d and D u d z i n s k i  Further  there  maximum  more s u b t l e weather  partially  herd.  in  the  speed and  l i n k e d t o changes i n animal b e h a v i o u r probability,  collected  variability  precipitation).  barometric  data  no  such  have  been  1978) and, i n daily  area  as  all  behavioural  is  required  to  v a l i d a t e such a s u g g e s t i o n .  Day t o day changes Hancock  (1954)  ruminating  in  behaviour  reported  times  variation  in  of  times  that  dairy  have  day  to  (1957)  also  found g r a z i n g  day  for  light  influence  factors\" grazing  and  non-consecutive d a y s . . . \" . suggestion. consecutive  January's  times  between  \"are  and  in  and  Hancock  days  sampling data,  other  biotic  the  grazing  60% o f  the  total  attributed  these  vary  unlike  Sheppard e t  as p r e v i o u s l y  of  on c o n s e c u t i v e  of  other  mentioned,  for  \"climatic  all  study s u p p o r t s  those  and  significantly  factors\",  alike  d a t a from t h i s  days,  to  grazers.  They suggested t h a t  more n e a r l y  January's  and b e h a v i o u r a l  domestic  i n weather and range c o n d i t i o n .  \"pastures  behaviour,  50  activities.  c a t t l e , but much l e s s so f o r c o n s e c u t i v e d a y s . or  for  differences  accounted  these  daily variations to fluctuations al.  to  cattle  devoted  been documented  which  than  on  Sheppard's  months,  were  showed no day  to  day v a r i a t i o n .  D.  An  E f f e c t s of P h y s i o l o g i c a l  aberrant  physiological  C o n d i t i o n on D a i l y A c t i v i t y  condition  such  grossly a f f e c t the c a p t i v e herd's diurnal  96  as  malnutrition  Budgets  appeared  to  more  p a t t e r n t h a n normal pregnancy.  The  \u000Cincreased  grazing  times  of  sick  animals  i n d i v i d u a l s may have been an e a r l y winter.  In  animals  December,  appeared  pronounced  than  to the  with  to  remainder  an  of  October  over  attempt t o improve t h e i r  declining  convert  in  health energy  the  and  low  While  of  healthy  condition  before  reserves,  these  fat  conserving  herd.  that  strategy  even  maintaining  a  more  foraging  e f f o r t e q u i v a l e n t t o o t h e r herd members, t h e a i l i n g a n i m a l s bedded l o n g e r and reduced  energetically  costly  activities  such  as  travel  and  social  i nteractions.  T h i s observed b e h a v i o u r a l available. than  fat  t r e n d seemed c o n s i s t e n t w i t h t h e l i m i t e d  A r n o l d and D u d z i n s k i sheep under a l l  pasture  e a t i n g f a s t e r than f a t sheep. cold),  a  reversed  grazing times  trend  (1978) g e n e r a l i z e d t h a t  was  noted,  ( A r n o l d and D u d z i n s k i  starvation  rates  energy  conserving  with 1978).  grazing  longer  sheep  in  poor  Similarly,  condition  usually  higher  bedding  (i.e.  reducing  Roby (1979) found t h a t  times  from high  than  a  better  Moen (1973) suggested t h a t a deer employing  strategies,  including  bedding w i t h  c o u l d reduce energy l o s s e s t o 2 x BMR even i n -40\u00B0C w e a t h e r . would be o f o b v i o u s  and  range i n Greenland and s u f f e r i n g  demonstrated  n o u r i s h e d c a r i b o u herd i n A l a s k a . several  by  \" t h i n sheep eat more  However, under extreme weather c o n d i t i o n s  a c a r i b o u herd from a poor w i n t e r winter  conditions\"  literature  importance t o an a i l i n g animal  its  head down,  Such a s t r a t e g y  during d i f f i c u l t  foraging  conditions.  The f a c t t h a t pregnant ewes i n t h e herd demonstrated no g r e a t e r f o r a g i n g t i m e s l a t e i n pregnancy than d i d b a r r e n ewes i s a l s o c o n s i s t e n t w i t h t h e ( A r n o l d 1962, A r n o l d and D u d z i n s k i  1978).  pregnant ewes have i n c r e a s e d n u t r i t i o n a l development,  it  appears  that  these  While i t  97  i s g e n e r a l l y accepted that  demands d u r i n g f i n a l  increased  literature  demands  are  stages of not  fetal  extensive  \u000C( B l a x t e r 1962) and a r e p o s s i b l y met by an i n c r e a s e than  an  increase  particularly  in  grazing  time  (Arnold  in  1962).  Such  a  rather  response  is  p o s s i b l e d u r i n g l a t e s t a g e s o f pregnancy when f o r a g e q u a l i t y  and  q u a n t i t y i s g e n e r a l l y h i g h and t h e f o r a g e i s e a s i l y  E.  rate of e a t i n g ,  harvested.  Energy E x p e n d i t u r e E s t i m a t e s f o r t h e Herd  The average  BMR's  estimated  for  the  herd members u s i n g C h a p p e l ' s  predictive  - 0 73 model  ranged  Kcal  kgW  from  - 0 73 *  Brody's  hr *  in  -  average  (Blaxter  2.75  Kcal June.  figure  1962).  KgW  for  *  hr *  These  values  mammals  I t would appear t h a t  h i g h e r than t h a t f o r domestic sheep. Ritzman and B e n e d i c t  (1930,  in  in  -  July  were  of  -  August  generally  2.94  Kcal  the estimated  to  4.79  higher - 0 73  than  kgW~ '  hr l -  b i g h o r n BMR's were  also  Both Marston (1948, i n B l a x t e r 1962) and  Blaxter  1962)  found FMR's  of  only  2.46  Kcal  - 0 73 kgW~ ' values  hr l  for  -  of  our c a p t i v e  seem u n r e a s o n a b l e , researchers For  hr-l  merino  bighorns  since  Blaxter  from  period.  (1962,  various In  However,  the  monthly  (and FMR's) specific Table  studies  addition,  ewes.  nor  BMR's  t o be both s p e c i e s  example,  estimated  adult  have  showed  ranged  Ritzman  variability  from  and  3.33  Benedict  the to  irregular  herd o n l y  seasonal  slightly  these  FMR's  4.01  (1938,  in  values  by  other  species.  of  Kcal Blaxter  steers - 0 73 kg 1962)  by 40% o r more, and they  v a r i a t i o n appeared t o be a s s o c i a t e d w i t h t h e time o f  y e a r , maximum v a l u e s b e i n g o b t a i n e d i n t h e s p r i n g and e a r l y The  of  elevated  variable within  that  . . . . \" f o u n d metabolism t o vary i n t h e same i n d i v i d u a l showed t h a t much o f t h i s  the  been demonstrated  and h i g h l y  17)  neither  fluctuations  resembled t r e n d s  (1978) found s p r i n g and p a r t i c u l a r l y  in  the  reported fall 98  BMR's  summer\".  developed  by o t h e r  for  the  researchers.  FMR v a l u e s t o be n o t i c e a b l y  captive Chappel higher  \u000Cthan  winter  animals  to  values. be  higher  (1973, b i g h o r n s ) . wild,  high  Chappel in  reduced w i n t e r  found and  seasonal  cervids  c a r i b o u and r e i n d e e r , the  spring  A similar  latitude  also  forage  intake  fall  than  trend  has been  (white-tailed  in  deer,  rates  reflect  a winter  of  winter,  as  et  his  study  did  recognized  Silver  McEwan and Whitehead 1 9 7 0 ) .  rates  Hebert  for  aK  several  1969,  1970;  I t has been suggested t h a t  \"growth  dormancy\"  period  (Reimer  1979) which e n a b l e s t h e a n i m a l s t o best cope w i t h low w i n t e r t e m p e r a t u r e s and food s h o r t a g e s .  The g e n e r a l l y h i g h e r s p r i n g t o f a l l  rates, in turn,  coincide  w i t h \" . . . t h e i n c r e a s e d energy requirements i n t h i s season due t o r a p i d g r o w t h , lactation,  moulting,  antler  Although the t y p i c a l  spring  values  were  unusually been  an  factors  estimated  for  growth -  early  the  and  increased  summer peak  captive  herd,  activity\"  and l a t e w i n t e r late  l o w , compared t o t r e n d s d i s c u s s e d above. artifact  for  of  the  based on a c t u a l  Chappel's  June  to  predictive  September  model,  period  were  on m e t a b o l i s m .  h i g h ambient t e m p e r a t u r e s From t h i s  information,  1979).  low i n BMR  summer-fall  BMR's  were  T h e i r low v a l u e may have since  seasonal  extrapolated  FMR r e a d i n g s from h i s study a n i m a l s .  do i n d i c a t e t h a t  (Reimer  correction  values  and  However, C h a p p e l ' s  (&gt; 10\u00B0C) have a d e p r e s s i v e  one c o u l d s p e c u l a t e t h a t  not data  effect  b i g h o r n s may  l o w e r t h e i r m e t a b o l i c r a t e s f o l l o w i n g peak r e p r o d u c t i v e and growth demands and prior  to  rutting  and p r e - w i n t e r i n g  d u r i n g t h e hot summer p e r i o d . heat direct late  loading,  in  poorly  solar radiation. summer  reduction  insulated  forage  c o n d i t i o n which would l i k e l y behavioural  studies  to  combat e x c e s s i v e  heat  B l a x t e r (1962) d i s c u s s e d t h e p o t e n t i a l  However, in  periods  domestic  bighorn intake  arise with  animals  researchers by  these  loading f o r such  exposed  to  have not  r e p o r t e d on a  animals  reduced m e t a b o l i c  (Hebert rates.  extensive,  1973),  Similarly,  (Kornet 1978, Van Dyke 1978, t h i s s t u d y ) have shown  o r no a v o i d a n c e o f t h e h o t t e s t p o r t i o n o f t h e day by b i g h o r n s ,  99  a  little  a behavioural  \u000Cp a t t e r n which s h o u l d have been e v i d e n t further  work  on l a t e  summer b i g h o r n  s a i d on t h i s a s p e c t o f t h e i r  Activity  costs  correlated  monthly  captive  their  herd d i d  BMR's  energy  not  metabolism  (r2  = .93,  rely  expenditures,  been  be t r u e ,  important  relatively direct energy  it  in  on  determining  returns  the  the  declining  Until  little  can  be  were  in  behavioural  spite  29.8  adaptions of  behavioural energy  of  activity  information  the  adjustments t o BMR.  net  significantly  to  that  modify  animals  were  While t h i s may  adaptions  balance.  may have  In  general,  ( w a l k i n g , r u n n i n g , \" o t h e r \" ) which o f f e r e d no  spring  from  basis  expenditures  herd's  comprised  from  completed,  &lt; 0.05),  can be demonstrated t h a t  expenditures  proportions  p  seasonal  since  \"expensive\" a c t i v i t i e s  energetic  is  One might c o n c l u d e from t h i s  p r e d o m i n a n t l y c o n t r o l l e d by p h y s i o l o g i c a l largely  l o a d i n g was a problem.  t h e herd on a monthly  budget changes o v e r t h e y e a r . the  heat  biology.  estimated for  to  if  a  decreasing  (April)  to  to  11.5%,  proportion  late  winter  respectively.  of  the  herd's  (March),  (Because  with  of  high  t r a v e l t i m e s i n December, i n t e r p r e t e d i n t h e p r e v i o u s s e c t i o n , t h i s t r e n d was disrupted s l i g h t l y essential  activities  energetic  returns  proportion exception with  of of  speculated of  (grazing,  (i.e.  the  that  assimilated  herd's  the  rising this  Conversely,  energy  animals,  forage)  at  in  expenditures  which  yielded  from A p r i l  to  March  during  to  84.9% i n  emphasis the  March.  improved  daylight  the  hours,  flow.  100  gross  (with  It net by  e l i m i n a t i n g t h o s e p e r i o d s o f high n e g a t i v e energy f l o w and i n c r e a s i n g o f p o s i t i v e o r n e u t r a l energy  yet  increasing  where g r a z i n g t i m e s were u n u s u a l l y  activity  least  \"inexpensive\"  comprised a g e n e r a l l y  from 67.7% i n A p r i l  shift  relatively  bedding-ruminating)  December and J a n u a r y ,  proportions  balance  in mid-winter).  the  low), can  be  energy largely periods  \u000CThe  extent  to  which  consistent  with  the  calculated  from  the  herd's  activity  literature.  the  costs  of  Moen  five  costs  exceeded  (1973)  different  found  regimes  of  of  Unlike t h i s  throughout  (i.e.  bedding,  the year.  Consequently,  ruminating)  began  to  60  kg  costs  s t u d y , Moen  (1973) demonstrated d e c l i n i n g m u l t i p l e s o f BMR from summer t o f a l l  value  a  BMR,  Similarly, activity  o f a 60 kg pronghorn were e q u i v a l e n t t o 1.45 x BMR.  However, t h i s d e c l i n e was l a r g e l y t h e r e s u l t  appeared  multiples  activity  w h i t e - t a i l e d d e e r , t o vary from 1.23 t o 1.98 x BMR.  BMR's  to winter.  o f Moen's use o f a s t a n d a r d BMR when  less  comprise  a  \"expensive\"  larger  activities  proportion  of  the  a n i m a l s ' d a y , t h e d a i l y a c t i v i t y c o s t s became l e s s e x p e n s i v e , r e l a t i v e t o BMR. Had Moen i n c l u d e d e x p e c t e d seasonal  variations  in  BMR, a l e s s  obvious  trend  would l i k e l y have a r i s e n .  That t h e peak l a c t a t i o n p e r i o d o f t h e c a p t i v e herd was t h e most e x p e n s i v e t i m e of  year,  even  researchers 1962)  more  of  animal  developed  caloric  value  so  than  pregnancy,  bioenergetics.  a  general  formula  (Kcal  kg-1)  = 304.8  lactation  this  milk  has  been measured a t  would  be  for  1962),  and  that  they  for dairy  produce  and  f  (f  milk  with  Gaines  energy  = % fat  875  1980),  the  Kcal k g *  of  -  used f o r  maintenance  in  of  milk,  where  content).  Since 44 days  caloric milk  cattle, at  a  value  of  1.6  on a d a i l y  101  basis.  least  kg  day-1  of  produced.  from M o l l g a a r d 1929, i n rate  of  Blaxter  a t c o n v e r t i n g m e t a b o l i z i b l e energy  p r o d u c t i o n f o r a b i g h o r n ewe would r e q u i r e a t  above t h a t  findings  (1933  content  v a l u e e s t i m a t e d f o r d o m e s t i c sheep d u r i n g peak l a c t a t i o n , milk  the  b i g h o r n ewe d u r i n g t h e f i r s t  5% ( A t k i n s o n  approximately  (estimated e f f i c i e n c y  the  + 114.1  Assuming t h a t sheep a r e 60% e f f i c i e n t milk  consistent  Overman  the f a t content of milk of a C a l i f o r n i a of  is  into  Blaxter (minimum  from Munroe 1 9 6 2 ) , 2300 Kcal  T h i s would  of  result  energy in  an  \u000Cenergy e x p e n d i t u r e 1.7 t i m e s t h a t e s t i m a t e d f o r May a c t i v i t y c o s t s , a m u l t i p l e even h i g h e r than p r e d i c t e d by Moen (1973) final  stages,  is  relatively  inexpensive,  f o r deer. a  a t t r i b u t e d i n d o m e s t i c sheep t o t h e r e l a t i v e l y in utero,  e s t i m a t e d t o be s i m i l a r  ( B l a x t e r 1962).  fact  Pregnancy, which  has  even i n largely  been  low m e t a b o l i c  r a t e o f t h e lamb  per kg o f w e i g h t t o t h a t  o f t h e a d u l t ewe  Consequently, . . . \" i n p r a c t i c a l t r i a l s ,  i t has been  t o measure any i n c r e a s e i n t h e energy needs o f t h e pregnant animal her t o t a l w e i g h t \" .  its  ( B l a x t e r 1962).  102  difficult per kg o f  \u000CSUMMARY  A.  Social Organization  Agonistic  1)  interactions  between  p r i m a r i l y comprised of butts conspicuous  adult  ewes  or horn t h r e a t s .  absence of horn d i s p l a y s ,  were  It  b r i e f . encounters,  is postulated that  characteristic  the  of bighorn rams, was  the r e s u l t of limited v a r i a b i l i t y in horn s i z e of the adult ewes.  2)  Interactions between ewes were infrequent, r e l a t i v e to that reported for  rams.  It  behavioural  is  postulated  strategy  that  adopted  this  reduced  by ewes  social  to minimize  activity  is  a general  energy expenditures  on  a c t i v i t i e s not v i t a l to maintenance or to reproductive success.  3)  A dominance hierarchy developed among adult ewes.  several  dominance  postulated that  reversals,  the  hierarchy  was  the homogeneously d i s t r i b u t e d  not  However, because of linear.  food resources  of  It  was  the ewes  reduced food competition, thus eliminating the need for a r i g i d l y maintained and orderly hierarchy.  4)  The hierarchy,  stable  over  the  although neither  study  period.  rigid  A rise  nor l i n e a r , in  status  of  remained  relatively  two r e l a t i v e l y  low  ranking ewes appeared related to t h e i r reproductive success.  5)  Neither  consistently  horn lengths correlated  nor body weights were shown to be strongly to  social  status.  103  Because aging techniques  and were  \u000Cconsidered  a c c u r a t e o n l y to s i x  and dominance number  of  1)  Dominant  subordinate  2)  be adequately initiated)  investigated.  was  feed.  were  not  based  on  It  was  shown  Aggressiveness  only  variable  (i.e.  found  to  be  status.^  have  comparison  postulated  of  that  higher fecal  quality  N and  dominance  diets  time  during  than  spent  at  feeding  is  to an animal o n l y when both feed and f e e d i n g spaces are  in s i m i l a r  Dominant  animals,  animals  limited.  resulted  activity  I t was p o s t u l a t e d t h a t s i m i l a r  were not  shown t o be more p r o d u c t i v e than  subordinate  winter m o r t a l i t y rates  I t was p o s t u l a t e d t h a t s i m i l a r d i e t s of the s o c i a l  in s i m i l a r  diets  budgets.  in terms of seasonal weight f l u c t u a t i o n s ,  lamb p r o d u c t i o n .  1)  between age  Dominant animals d i d not have reduced f e e d i n g times or i n c r e a s e d bedding  resulted  C.  the  to  times compared to s u b o r d i n a t e a n i m a l s .  3)  age, the r e l a t i o n s h i p  Dominance  animals animals,  supplemental  of  and c o n s i s t e n t l y c o r r e l a t e d to s o c i a l  Consequences of  beneficial  not  interactions  significantly  B.  could  years  l e v e l s of  or  classes  productivity.  Forage A v a i l a b i l i t y and Herd Behaviour  The  herd's  diurnal  activity  f e e d i n g and bedding p e r i o d s declined periods.  in  number  Although  and  pattern  in s p r i n g increased  daylength  was  characterized  and summer. in  duration  and weather  104  Activity during  conditions  were  by  successive  peaks  fall  generally  and  winter  shown t o  effect  \u000Cactivity rates were  patterns  to  i n the f a l l more  a minor  and w i n t e r  directly  degree,  it  was p o s t u l a t e d  that  resulting  from d e c l i n i n g  forage  responsible  for  the  increase  in  reduced  intake  availability  duration  of  activity  bouts d u r i n g t h i s p e r i o d of the y e a r .  2)  Although d a y l i g h t  year,  g r a z i n g times were r e l a t i v e l y  w i t h the e x c e p t i o n  daylight  of  (March).  periods.  The  c o i n c i d e d w i t h the most food s u p p l y ,  Prior  increased death,  times  inclement  weather  of  in  December  the w i n t e r  of to  reduced  nocturnal  and  January  and a supplemental  respectively.  to  their  grazing  moribund  winter  times animals  C o n d i t i o n on D a i l y A c t i v i t y  deaths,  relative  Budgets  most  moribund  animals  to healthy  animals.  Immediately  generally  bedding times r e l a t i v e t o h e a l t h y  2)  (April)  and l a t e w i n t e r months by i n c r e a s i n g grazing  the  the p r o p o r t i o n  i n c r e a e d from e a r l y s p r i n g  reduced  E f f e c t s of P h y s i o l o g i c a l  1)  throughout  I t was p o s t u l a t e d t h a t animals compensated f o r  i n t a k e r a t e s d u r i n g the f a l l  D.  and January v a l u e s ,  devoted t o f e e d i n g g e n e r a l l y  l a t e winter  grazing  December  constant  had s i m i l a r  grazing  times  demonstrated  but  increased  signifi-  animals.  E.  Energy E x p e n d i t u r e E s t i m a t e s f o r the Herd  1)  Both average BMR's and d a y l i g h t  in spring ( A p r i l  to  animals.  The f e e d i n g and bedding times of pregnant ewes d i d not d i f f e r  c a n t l y from non-pregnant  prior  activity  t o June) than in summer, f a l l  105  c o s t s f o r the ewes were h i g h e r and w i n t e r .  \u000CIt  was  demonstrated  values,  the  proportion  2)  providing  gross  that, of  energetic  with  the  daylight returns  g e n e r a l l y i n c r e a s e d from s p r i n g ( A p r i l )  106  exception  energy (i.e.  of  devoted feeding,  to l a t e w i n t e r  December to  those  and  January  activities  bedding-ruminating) (March).  \u000CBIBLIOGRAPHY A l e x a n d e r , G. 1961a. Energy e x p e n d i t u r e and m o r t a l i t y i n new-born lambs. P r o c . 4th I n t e r n a t l . Cong. Anim. R e p r o d . , 3 : 6 3 0 - 3 7 . A l l d e n , W.G. and J . A . McD. W h i t t a k e r . 1970. 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