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See ss Spee et Par eS een ee ee Pe eee Ss a eee ea SS 2 nen tm = ren eee SS ee eee SSeS an =e Se Siere ae : ae ee eee eee = ee Seay eee ee eee ee a eh hae Poet << SS ee ie ete tee ee = Sst ee pe ee re a ee ee Se Se pats —— ee ee eo Re pe eg pee Se Spee Ses eee en ar eer Ee ee Sey : ¥ or ies i rt Tih + wn) ay Ne tye ' i itt) | - i i ‘ie aa - if i. 7 oe, a te = ig: 7 s ‘2 i Se a ‘- ee Pee . ie ‘. ' ' ‘ - re 4 + 4 ' 7 ' , | - « 1 1 ; p ‘ ‘ .. - 1 : cd } i ‘ } ps - =) a ‘ ‘ 1 ' \ J + - ' j 3 :. i. ? i ‘ ‘ o : ' | ; ' ; : . ‘ ; » f - i i , , ! rm é SMITHSONIAN INSTITUTION UNITED STATES NATIONAL MUSEUM Bulletin 113 Rs iP LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS 6 a ORDER LONGIPENNES BY ARTHUR CLEVELAND BENT Of Taunton, Massachusetts WASHINGTON GOVERNMENT PRINTING OFFICE 1921 1 ' , i * a ; : ’ ; : } 1 J a be { - 7 ‘ ‘ e 7 ‘ - + c e © a i : 0. * : ' )e Ps - : ‘ 1 ‘4 i, PEs 113 BULLETIN NATIONAL, MUSEUM S. U. “qf I *H "6SE ANVd AAS NOlLdIHOS3q HOY “TINH ONIHSNV] *euUBISINO'T ‘puRIs] a10peT ye SMITHSONIAN INSTITUTION UNITED STATES NATIONAL MUSEUM Bulletin 113 LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS ORDER LONGIPENNES BY ARTHUR CLEVELAND BENT Of Taunton, Massachusetts WASHINGTON GOVERNMENT PRINTING OFFICE 1921 os beats aut OFF eee ‘ SEW Aye : “ww ts? a ' I OVITA ; La Ain ry a #2 &! R z je AssTf ee. Off. ADVERTISEMENT. The scientific publications of the United States National Museum consist of two series, the Proceedings and the Bulletins. The Proceedings, the first volume of which was issued in 1878, are intended primarily as a medium for the publication of original, and usually brief, papers based on the collections of the National Museum, presenting newly-acquired facts in zoology, geology, and anthro- pology, including descriptions of new forms of animals, and revisions of limited groups. One or two volumes are issued annually and dis- tributed to libraries and scientific organizations. A limited number of copies of each paper, in pamphlet form, is distributed to specialists and others interested in the different subjects as soon as printed. The date of publication is recorded in the tables of contents of the volumes. The Pulletins, the first of which was issued in 1875, consist of a series of separate publications comprising chiefly monographs of large zoological groups and other general systematic treatises (oc- casionally in several volumes), faunal works, reports of expeditions, and catalogues of type-specimens, special collections, etc. The ma- jority of the volumes are octavos, but a quarto size has been adopted in a few instances in which large plates were regarded as indis- pensable. Since 1902 a series of octavo volumes containing papers relating to the botanical collections of the Museum, and known as the Contribu- tions from the National Herbarium, has been published as bulletins. The present work forms No. 113 of the Bulletin series. Wiuuram vEC. Ravenet, Administrative Assistant to the Secretary, In charge of the United States National Museum. Wasuineron, D. C. it baa on . oe. ae {enoiieh oper: to cue ag atenames a —— -50) asaiteent sidsmoteza [sr9n93, odio ‘bas, ay seOTs _ghoidibeqze to etoger adzow Ldanst ,(zscanloy Lex -sct sdf .939 2noiioslios (aindge aqsutinaae-sqyd 1 eaiaatn ased ae oe & ane coal ta mae Pan INTRODUCTION. This Bulletin contains a continuation of the work on the life his- tories of North American birds, begun in Bulletin 107. The same general plan has been followed and the same sources of information have been utilized. Nearly all of those who contributed material for, or helped in preparing, the former volume have rendered similar service in this case. In addition to those whose contributions have been previously acknowledged, my thanks are due to the following contributors : Photographs have been contributed, or their use authorized, by D. Appleton & Co., S. C. Arthur, A. M. Bailey, R. H. Beck, B. S. Bowdish, L. W. Brownell, G. G. Cantwell, F. M. Chapman, H. H. Cleaves, Colorado Museum of Natural History, E. H. Forbush, A. O. Gross, O. J. Heinemann, A. L. V. Manniche, W. M. Pierce, M. S. Ray, J. Richardson, R. B. Rockwell, R. W. Shufeldt, J. F. Street, University of Minnesota, C. H. Wells, J. Wilkinson, and F. M. Wood- ruff. Notes and data have been contributed by S. C. Arthur, R. H. Beck, F. H, Carpenter, H. H. Cleaves, E. H. Forbush, F. C. Hennessey, R. Hoffmann, F. C. Lincoln, H. Massey, O. J. Murie, C. J. Pennock, J. H. Rice, Katie M. Roads, and G. H. Stuart. With the consent of Dr. L. C. Sanford and R. H. Beck, the American Museum of Natural History has placed at the author’s disposal Mr. Beck’s extensive notes made on the Brewster and Sanford expedition to South America. The distributional part of this Bulletin has been done mainly by the author, with considerable volunteer help from Mr. F. Seymour Hersey, whose time is now otherwise occupied. Dr. Louis B. Bishop has devoted much time to revising the paragraphs on distribution and on plumages. Our attention has been called to an error in Bulletin 107. On page 32 a quotation from Dr. T. S. Roberts was inserted as referring to the food of the eared grebe; this really refers to the food of Franklin’s gull and not to that of the grebe. Readers of Bulletin 107 have suggested some changes. Conse- quently, in this and subsequent Bulletins in this series, the exact details will be given, when available, in such casual records as are given; but it must be remembered that no attempt will be made to t VI BULLETIN 113, UNITED STATES NATIONAL MUSEUM. mention all casual records; only a few can be given, to suggest the limits of the wanderings of the species. Another addition of value, suggested and furnished by Dr. T. S. Palmer, is information regard- ing reservations and the species which are protected in them. As some readers have questioned the scale on which the eggs are illus- trated, it seems desirable to say that in Bulletin 107, in this one, and in subsequent Bulletins, all eggs are, and will be, shown exactly life- size, the plates being produced by an exact photographic process. Tue Avrnor. TABLE OF CONTENTS. Mami VU SUCRCORATION Gs] Scene ee eS @atharacta ska == eee ee ee ee DTS ERE UE O Ties eh ee he nk a eee @WatharserrehilensSigns sia. oe en ORV chara Uae ee ee Se ee eee VSR RUS ea ee es. TRB D TESS feeb UC TR rn creek a ek ee SLerconauusnpoMmarinus.= 2226 28 ok  ate ae Fe a ee Eee hy Reem eae ae ef ee ee ROP ESSt Nor PUEBLA) Ne eos Ea 2 ST ee ee SLeLCOMPrIUS: IONPICAUGUS 2 Se ee OHS LATICES Om Glorieta Pee a ETP ee ia cred ean Be Mes Lee ae BESTEL OTN fe tt teen Se eR ee REeU EV aw TON LOR Or se Stet a ee ih Sk NE SS Aer ay iat ekgy ahh by hee ee a ys COTS Vea ee ee ene a eT ee PRET Tig ee rw ne ra ermal Be cee A eg as os aes Fes PRODESS Cosh Eva) Coe et a Sa Se ee ARISSaM ETC ACEYyI a. LLIGACLY 1a Et oe PRRSRCS ET Varese tee eran ac AS. 9 SRL eRe TP a tay oe Bg ce ARES VE Seg =e AS yl aS eee 2 ee eS ANODE ESTE Ghd 0 Tee ee i I A aS HAISSAMCTICACLYIE (DOLNCALIS =o See hae ee see eee ee IPAPIG Om ler GhiWial ke sas see ee eee, ae PS Se eee IRE a iss ose Se Bae ee OSCR eULOMeee Sea ie eu ale ees Sg Cae eS ae Maris DV PeCrDOLCHS 2 = bs oo Se 2 ee ee es ee ee WUISITTCO Sie OUD tea cerns oly ee ee ee ee ReMCaLs EU Reet apetmmetne Sr see Ols h aP e HURT EVEN ET OW es re ee ee ee es ee eA LUMmIEECOULCLUS Sone Le ces oe I ee aS oe Gel stanermrorine cease ee ee a eee EATER SE Reena seen ee ad alles Ca eee ES an eo ee ee net PURER ARNG UU OL Lek CONN Pe ase rr te ee ee Page. pt pee et PRWTANAQAN A OHHH HB _ He 28 VIII TABLE OF CONTENTS. Family Laridae—Continued. Page. IEBTUS) LIATICCSCEMS! ei See oe ike AEs NO este ree een eee pas Se 65 GIS COUS= WATS Cd eT a Ne lee VMN PAR ey LR Ne SN Noe 65 Eabitees = | 2280S eg IS pra Ra Ee ae eis ert OE ee 65 PAS tere EON st ae rte aa a Se weg ede. lags 73 Darus. Family Laridae—Continued. SPST 2 Tne Coa in ee tre eS oe os I SO DREHER ER a SS Ri a OE Ha rUse pute Oe No tie ee eee oes eee ES ee SES TVD rsa Lectin a rece ng ee Pe a ee TE Tea pei ss omen nae ered ee Re ie ee ee nee eae el TD ISS ELGLO Mase Ne ee ee ee 2 ee MPiy sd SUMS MoT VAME TUR SUS er co kN ee a a eee Gui lems Samlleemo meres sd wee ee ee ee ae FERED Sees eee Be GRE Reh he A OT SERS Fed ee hd POP TSSESPSI CULO Ta ses ee a ee! ee ee ey he eee RUBOGOStCEBT ANT OSCA 2 2 fx = 8 a ee nl ae eh NOS S| SOT) Meee Ss = Sees Fo ee ha a ie te BF Tein ice 2 Ae ok be ee ce ee, 2. Family Laridae—Continued. Page. PUy CGE WU? 3 fT a ee ee 227 Habits ee re St ee 227 DESH PA Tetra ee SEES 228 Starman forste rns = ene eS I ee ee ees ORE 229 Worse LS Here ea ee 229 ART Sa DW Ss a aaa ee 229 Disbribrsti on jee a ee 235 Sterna: hirundo. 2&2 se ee a ee ee ee 236 Crm OT ea ea a ee ee 236 TED ea UGS 2 eee ae eA ta 236 ME Stereo rae ee Ee ee 248 Sterna: paren Cis ay eats Se ee eae pea gee 249 ACETIC TODD eT Een SA Sa ce Rg sat oe 249 ERDAS ess a ek cs ee eee A ain ea 249 MUSE rea ba ct Ora ee a a re ee a 255 Serre CO Ui eee ETS Bs a ec a cr teeeee e e 256 TRC SEESU TEs iE NCTM se ee tee Ip ee eg SL Dg 256 BREMEN ES ee a FR a ia Re A Sy at area 256 DISEL TD UEN ON eS ae gaa or a 264 Sterna ple meica sac re es ee a a aig a Dy ma Ee 265 PANT Ty ER RUC Tera a Se SS I a POE cl da SS ee 265 SEW By AGS Sacre ete sane em oma ese aera Re ee 265 SUDA Eee Ga GE EN ea aL sc rs ae 269 Sterna: -antillarum:.- 2.22 ~ += ee ape Si ey any PO 270 WheaSted@rn i222 282 a ee i re SE ee 270 SBEW SB RS fA I a 270 ESE rea PU CO rac a iS ae a 278 Ste remiss Cant as a a a ee Renae 279 Soo bay te rene a a a ee ee 279 TENN Tt he Se Ty 2s 279 USED TLON el A ek ae 286 Sternavcanaethetar: 02k 2 a eS ee ee eee 287 MBE eR LG heat eT NER EO Se pl eed 287 Wa bits. 2 2c 3 ae a ean ele 287 US GrEP TUE a a Le 289 Chiidonias nigra: Ssurinamensis ss 2 oe ee eee 290 Peer kesh rea! Se oe pow Re Pe 290 FMA UD EES ese Aa a pe Lk Bh ee gen ce a 290 DUS trib WE TO Mae a pea ih ak ahaa a See 298 Chiidontas*leucoptera. By Artuur CLeyELAND Bent, of Taunton, Massachusetts. Family STERCORARIDAE, Skuas and Jaegers. CATHARACTA SKUA Briinnich. SKUA. HABITS. The following quotation from the graphic pen of Mr. F. St. Mars (1912) gives a better introduction to this bold and daring species than anything I could write, and his article, The Eagle Guard, from which I shall quote again, is well worth reading as a striking char- acter study: Then the scimitar wings shut with a crisp swish, and he became a statue in duH, unpolished bronze, impassively regarding the polecat, who lay with her back broken, feebly struggling to drag into cover. It is a shock to the human nerves to see the life blasted out of a beast almost ’twixt breath and breath; what one moment is a gliding, muscular form, instinct with life and energy, confident in power, and the next moment a crumpled heap of fur, twitching spasmodically. But it was a searchlight on the reputation of the eagle guard and the stories one had heard anent the superstitions of the natives. The polecat, being hungry with the gnawing hunger of a mother and pre- suming on a swirl of mist, had tried to steal up the knoll to the two great eggs that lay in the hollow atop all unguarded. Had come then a thin, high, whirring shriek, exactly like the noise made by a sword cutting through the air, and a single thud that might have been the thud of a rifle bullet striking an animal. Then—well, then the scene described above. Big, powerfully built, brown with the black brown of his own native peat bogs, armed to the teeth, long and slash-winged, whose flight feathers were like the cutting edge of a sword, insolent with the fine, swelling insolence of power, and greatly daring, no wonder men had chosen him as the eagle guard, this mighty bird, this great skua of the naturalists, this Bonxie, mascot, and super- stitious godling of the fishermen. Wah! he was a bird. We know so little about the skua, as an American bird, that I shall have to draw largely from European writers for its life history. It is rare on the American side of the Atlantic Ocean, and is not known to breed here regularly, although it probably does so occasion- ally or sparingly in Greenland or on the Arctic Islands. 2 BULLETIN 118, UNITED STATES NATIONAL MUSEUM. Nesting —Yarrell (1871) says: The great skua arrives in the Shetlands about the end of April, and its nest, which consists of a neatly rounded cavity in the moss and heather of the highest moorlands, is prepared in the latter half of May. According to Maj. Feilden, the birds appear to prepare several nests before they decide on using one. There is no difficulty in finding the nests, as the parent birds at once attack any intruder upon their domain with fierce and repeated swoops. When handling the nestling the editor found their assaults were unremitting; first ene bird and then the other wheeling short,.and coming down at full speed, almost skimming the ground. At about 15 yards’ distance the strong clawed feet are lowered and held stiffly out, producing for the’ moment a very ungainly appearance, and it seems as if the bird would strike the observer full in the eenter of the body, but on quickly raising the hand or stick the bird rises also, the whirr and vibration of its pinions being distinctly heard and felt. Its ordinary flight is Soaring and stately. On leaving the territory of one pair, the attack is taken up by another, and so on; for the great skuas do not nest in close proximity. Morris (1903) writes: The nest of the skua is of large size, as well as somewhat carefully con- structed; the materials used being grasses, lichens, moss, and heath. The bird places it on the tops of the mountains or cliffs in the neighborhood of the sea, but not on the rocks themselves. They build separately in pairs. Eyggs.—The skua lays ordinarily two eggs, rarely three, and some- times only one. These vary in shape from ovate or slightly elongated ovate to short ovate. The shell is smooth, with a dull luster. The ground color is “ Saccardo’s olive,” “Isabella color,” or “ deep olive buff.” The markings are usually not profuse and consist of spots and blotches, scattered irregularly over the egg, of “sepia,” “ bis- ter,” “snuff brown,” or “tawny olive.” There are also usually a few faint spots or blotches of pale shades of drab or gray. Rev. F.C. R. Jourdain has collected for me the measurements of 68 eggs, which average 70.58 by 49.43 millimeters; the eggs showing the four ex- tremes measure 76.3 by 50.4, 71.5 by 53.2, and 62 by 44.5 millimeters. Young —Macgillivray (1852) quotes Captain Vetch as saying: The young bird is a nimble, gallant little animal, and almost as soon as hatched leaves the nest. On the approach of danger he secretes himself in holes or behind stones with great art, and when captured at least makes a show of defense that is quite amusing. Plumages.—I have never seen the downy young, but Coues (1903) describes it as “buffy-gray, ruddier above than below.” Ridgway (1887) quotes Dresser as calling it “brownish or cinnamon-gray, rather darker in color on the upper parts than on the under surface of the body.” I have not been able to examine enough specimens to come to any definite conclusions as to the sequence of molts and plumages. Coues (1903) gives the following good description of the young of the year: Size much less; bill weaker and slenderer; cere illy developed; striae not apparent and its ridges and angles all want sharpness of definition. Wings U. S. NATIONAL MUSEUM BULLETIN 113 Ris Job. Kk. I Chatham, Mass. Wilkinson. ie Kaldafarnes, Iceland, POMARINE JAEGER SKUA. FOR DESCRIPTION SEE PAGE 329. LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 3 short and rounded, the quills having very different proportional length from those of adults; second longest, third but little shorter, first about equal to fourth. The inner or longest secondaries reach, when the wing is folded, to within an inch or so of tip of longest primary. Central rectrices a little shorter than the next. Colors generally as in adult, but duller and more blended, having few or no white spots; reddish spots dull, numerous, and large, espe- cially along edge of forearm and on least and lesser coverts. On underparts the colors lighter, duller, and more blended than above; prevailing tint light dull rufous, most marked on abdomen, but there and elsewhere more or less obscured with ashy or plumbeous. Remiges and rectrices dull brownish-black ; their shafts yellowish-white, darker terminally. At bases of primaries there exists the ordinary large white space, but it is more restricted than in adults, and so much hidden by the bastard quills that it is hardly apparent on outside of wing, though conspicuous underneath. Young birds may become indistinguishable from adults at the first postnuptial molt, when a little over a year old, but perhaps not for a year or two later. Adults seem to have but one complete molt—the postnuptial—in August. Adults can be distinguished by their larger size and by the elongated feathers of the neck with the whitish central streaks. Food.—Yarrell (1871) writes of the food of the skua: Their food is fish, but they devour also the simaller water birds and their eggs, the flesh of whales, as well as. other carrion, and are observed to tear their prey to pieces while holding it under their crooked talons. They rarely take the trouble to fish for themselves, but, watching the smaller gulls and terns while thus employed, they no sooner observe one to have been successful than they immediately give chase, pursuing it with fury; and having obliged it from fright to disgorge the recently swallowed fish, they descend to catch it, being frequently so rapid and certain in their movements and aim as to seize their prize before it reaches the water. The stomachs of a pair which were shot were full of the flesh of the kittiwake, and the castings consisted of the bones and feathers of that small gull. Heysham has noticed an adult female on the coast of Cumberland, which allowed herself to be seized while she was in the act of killing a herring gull. It also feeds on fish offal, and the editor found by the side of a nestling some disgorged but otherwise uninjured herrings of large size. Behavior.—In appearance as well as in habits the skua seems to share the attributes of the Raptores and the Laridae; its strong, hooked bill and its sharp, curved claws enable it to stand upon and rend asunder the victims of its rapacious habits. Its flight is also somewhat hawk like. Yet it stands horizontally and runs about nimbly like a gull. Morris (1903) says that it “soars at times at a great height, and flies both strongly and rapidly, in an impetuous, dashing manner.” Mr. Walter H. Rich has sent me the following notes on the flight of this species: When on the wing, which is the greater part of the time, the skua shows in the air hawk like, rather than like the gulls, with whom we rather expect 4 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. to find its resemblances. Its appearance in the air is somewhat like the puteonine hawks, except that its wing action, in its seemingly restrained power and forceful stroke, suggests the unhurried flight of a falcon, or, perhaps, more accurately—since the wings are at all times fully opened, employing their full sweep in their action, their primaries slightly separated at the tips and slightly recurved—the majestic flight of an eagle. The wing spread is ample, the wing well balanced in its proportions of length and breadth, well combined to produce both power and speed. The figure is somewhat burly and chunky as compared with the lighter appearance of the gull and the more racy lines of the yager. The impression of muscularity is heightened by the short, square-cut tail, carried somewhat uptilted, giving the fowl an appearance unmistakable in the eyes of one having ence recognized it. This peculiarity of tail, which to me seemed slightly forked instead of having the central feathers lengthened, as in others of this group, together with the broad white patch across the bases of the primaries, furnishes a good field mark for the identification of the species. Macgillivray (1852) says: Its voice resembles that of a young gull, being sharp and shrill, and it is from the resemblance of its cry to that of the word skua or skui that it obtains its popular name. Mr. Rich’s notes state: Whatever the case elsewhere, on the fishing grounds this seemed a silent species. The writer heard no sound at all which he was able with certainty to trace to it during his acquaintance with it. The most interesting phase of the skua’s life history is its behavior toward other species. It is certainly a bold and dashing tyrant, more than a match for anything of its size and a terror to many birds and beasts of larger size. Mr. F. St. Mars (1912) describes. its attack on the golden eagle, which dared to venture too near its nest, in the following graphic words: Some minutes elapsed, in spite of the warnings, before the human. eye could have made out a faint dot growing out of the mist round tbe tail of an inlet. It enlarged rapidly, however, that dot, and one saw that it was really a real, live eagle, a golden eagle of Scotland. Mind you, there was none of that sublime soaring in the infinite that the books tell of. He came, as any mere common bird might have come, beating up along the shore with heavy, flapping flight, which, by the way, looked much slower than it really was, and he said nothing as he came. The picture, as it stood, of that somber, bronze-gold winged giant, beating slowly up against the wind in a setting of dim gray sky, jade sea, and dark- velvet land, was very fine. It seemed that nothing could have added to its bold, wild grandeur. Then something seemed to move across the heavens very quickly, and there was a hissing sound as if a mighty sword had cleaved the air. Followed then a second phenomenon just like the first, and almost in the same instant one realized two distinet facts: Firstly, that the two skuas were no longer near their nest; and, secondly, that the eagle had, with five stu- pendous flaps of those vast wings, shot upward into the clouds. eee 1 LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 5 At the same instant it seemed as though a big brown projectile hurtled past exactly beneath him, and a fraction of a second later, as though another one had hit him. There was a burst of feathers and a whirl. The eagle appeared suddenly to grow much larger, miraculously to sprout an extra and smaller, thinner pair of wings, and to reel in his flight, recover, reel again, turn half over, as if grappling some invisible foe, drop like a thunderbolt some 200 feet, and then break into two pieces, the larger piece slanting upward on the one hand and the smaller executing the same wonderful aerial evolution on the other. Then were the facts made plain. The smallez portion was the skua. He had darted like lightning upon the eagie’s back and clung there for a second or two— only for a second or two, but it seemed minutes while the two fell—after the king had avoided his mate’s first reckless, headlong, crazy rush. I have no hope to describe to you what followed, because the laboring human eye was far too slow to see and the brain to grasp the electric-quick passage of events. I only know that one was dimly aware that some stupendous battle was going on up there in the dim northern heavens; that bodies, large bodies, bursting with life and a dozen uncurbed wild passions, were sweeping and swerving, and swooping, and swaying, and streaking, and stabbing, and slash- ing, and striving, and screaming in one wild weiter of wildering speed. And all the while the land below, save for the huddled sheep, lay as deserted as if a hand had come down and swept it clean of life. Yet one knew that in reality hundreds and hundreds of sharp eyes were watching from cover that battle of the overlords of the air and calculating the chances of life upon its issue. Slowly, second by furious second, inch by hard-fought inch it looked from the earth, but mile by mile it was really, up there in the unbounded airy spaces, the battle receded, receded upward and northward, til! the straining eye was at last only conscious of a faraway blur, a dancing of specks, as it were gnats, on the vision, and then, with an almost audible sigh from the hidden specta- tors, of nothing. Mr. Rich’s impressions of the behavior of the skua are expressed in his notes as follows: This is the overlord of the fishing grounds, fearing no bird here. Whether the skua would successfully contest with the black-backed gull the writer is unable to state, as the two did not come together under his observation, but he thinks that the skua need have little uneasiness as to the outcome of bat- tle. The difference in size between the black back and the skua is mostly a matter of measurements, due in part, at least, to the skua’s shortness of rudder. In bulk and weight there is less difference, probably, than is shown by these figures, and in physical powers, judging from appearances, there is little to choose between them. Of the two, the skua’s armament seems the better fitted for damaging an enemy, and he seems to possess greater speed and skill in maneuvering—a flight of greater power and control than has his rival, who, gull-like, is a drifter rather than a flier. Certain it is that the hag, tern, kittiwake, and herring gull move respectfully aside when the “sea hen” comes sailing above them, for all these he harries and robs constantly, performing in the realms of the sea the same robber tactics which the raptorial birds carry on among the feathered people ashore. Are the hags or the gulls squabbling over a bit of waste or striving to tear a “ poke-blown”’ fish which has drifted away from the steamer’s side; over the struggling mass there comes the shadow of broad wings; a heavy body drops among them regardless of what may be beneath it; the weaker move respectfully aside and leave the 6 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. newcomer in undisturbed possession of the spoil. Over his shoulder the skua gazes at the steamer, making only now and then a tentative pull at the body of his prey, until it has floated to a safe distance, when he begins to rip and tear it with his powerful beak. To lose all interest in that particular morsel, hag or gull that comes near the spoil needs to look but onee at that lowered head with its bristling crest, and the powerful wing upraised to strike. Winter.—The status of the skua as an American bird is based largely on its occurrence on the fishing banks off the coasts of New- foundland and New Engiand. Probably the birds which occur there in winter are of this species, but the following notes by Mr. Rich suggest the possibility that the birds seen there in summer may be of one of the Antarctic species: In the main, the “sea hen” seems to have been considered a winter visitor to our coasts, somewhat unusual during the summer months, yet my records show its presence here from June 19 to November 5, with its period of greatest abundance from August 12 to September 10 (this in the ‘South part of the channel,” 35 miles east; south from Sankaty Head, 68° —42’ W.; 41° —20’ N.), with numbers diminishing thereafter until the last appearance therein noted on November 5, 1915. The writer remained upon the fishing grounds 21 days later, but did not again note its presence there. These facts have suggested to Mr. Norton that the “sea hen” of the sum- mer months may have come from the Antarctic with the shearwaters, returning thither to breed among the penguin rookeries of that little-known continent on the underside of the world; while the skuas of the winter months may come from the northern breeding grounds of the species. It is regrettable that I was unable to collect any specimens with which to make comparisons and to go deeper into this matter. There would have been very little difficulty in getting material, as the “sea hen,’ while more careful than the “ gull-chasers,’”’ was not very shy, and shots at 30 yards or even less would have been frequent. DISTRIBUTION. Breeding range.—Islands of the North Atlantic Ocean, Greenland, Iceland, the Faroe and Shetland Islands. Said by Kumlien to breed at Lady Franklin Island north of Hudson Strait. Winter range.—The North Atlantic Ocean, occasionally reaching land. From the Great Banks, off Newfoundland, and Georges Bank, off Massachusetts, to New York (Long Island). In Europe from the British Isles and Norway south to Gibraltar. Occasional in the Mediterranean Sea and on inland waters. Spring migration.—Migration dates in North America are so few as to appear little more than straggling records. Labrador: Straits of Belle Isle, June 22. Fall migration.—Birds reach Georges Bank in July. Massachu- setts dates: Ipswich, September 17; Woods Hole, August 30 and Sep- tember 19; Pollock Rip, September 10; and Nantucket Shoals, Octo- ber 17. Recorded from New York (Long Island) as early as August 10. LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. i Casual records.—Accidental inland in New York (Niagara River, spring, 1886). Egg dates.—Iceland: Twenty-four records May 20 to June 23; twelve records June 3 to 15. Greenland: One record June 21. CATHARACTA CHILENSIS (Bonaparte). CHILEAN SKUA. HABITS. The preceding species, Catharacta skua, has been reported, as a straggler, on the coasts of California and Washington, where speci- mens have been taken, as recorded below. These records have always seemed open to question as it seemed unlikely that a bird of the Atlantic Ocean would stray so far away from its normal habitat. There are at least two other species of skua, which are fairly com- mon in certain parts of the South Pacific and South Indian Oceans, which would be much more likely to wander to the coast of Cali- fornia. Thinking that these records might refer to Catharacta chilensis or Catharacta lonnbergi, I opened correspondence regard- ing them with Mr. Harry S. Swarth, which resulted in his sending me one of the birds. After consultation with Mr. Robert Cushman Murphy, who is familiar with these species in life, and after compar- ing it with series of specimens of chilensis, lonnbergi, and antarctica in various museums in Cambridge, New York, and Washington, I have decided to provisionally refer these birds to the above species, Catharacta chilensis, of which they probably represent an immature plumage or a dark phase. DISTRIBUTION. Breeding range —Unknown. Range.—Most abundant on the coasts of Chile and Peru, but found on both coasts of southern South America, from Rio Janeiro, on the Atlantic side, to Callao, Peru, on the Pacific side. Wanders north- ward, perhaps regularly, in the Pacific Ocean to Japan (Sagami Sea, August 23, 1903), California (Monterey Bay, August 7, 1907, and August 4 and September 21, 1910), Washington (off Gray’s Har- bor, June 28, 1917), and British Columbia (off Vancouver Island, June 20, 1917). STERCORARIUS POMARINUS (Temminck). POMARINE JAEGER, HABITS, To most of us this and the other jaegers are known only as sum- mer and fall visitors on our coasts or on the fishing banks, where they are constantly harassing the smaller gulls, the terns, and the shearwaters, from whom they obtain by force a large part of their food supply. The pomarine is the largest of the three, but by no 174785—21——_2 8 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. means the most aggressive. Few of us have ever seen it on its breed- ing grounds, which lie within the Arctic Circle, where it is widely scattered over the boundless plains of the marshy tundra. Spring.—Dr. E. W. Nelson (1887) says of its arrival in northern Alaska : The earliest arrival of this bird in spring was May 13 at the Yukon mouth where the writer found it searching for food along the ice-covered river chan- nels. They became more common, until, by the last of the month, from a dozen to 20 might be seen every day, Mr. Frank C. Hennessey, who accompanied the A. P. Low expedi- tion to the regions north of Hudson Bay, says, in his notes, that “ the first of this variety was seen to arrive in the spring at Winter Har- bour on May 29th.” Nesting.—Very little has been published on the nesting habits of the pomarine jaeger. Mr. Hennessey, in the notes referred to above, which he kindly sent me, states that these birds are “ abundant about Winter Harbour, where they breed on the low, flat, marshy land in the neighborhood, choosing the small mounds or slight elevations that abound in these places upon which to rear their brood. The nest is a slight depression in the soil of the elevation and just deep enough to admit the eggs and breast of the bird. No material is used in its construction, but the bottom is covered with much loose soil and rub- bish apparently blown in accidentally.” Mr. C. Boyce Hill (1900) published the following account of the nesting habits of this species in Siberia: On our way down the Yenisei the steamer which was towing us fortunately ran ashore on one of the numerous sand banks which abound in this river. I say fortunately because it enabled us to discover this skua nesting. After having inquired the probable duration of our stoppage, Popan and I agreed to explore the small islands near at hand—a group named the Brekotsky. We took one each, and on mine, a large, flat marsh, I observed a Pomatorhine skua, which was presently joined by another. The birds did not appear at all demon- strative nor to resent intrusion, like the long-tailed skuas, so I thought they could not be nesting. But after much searching and watching I observed one settle right in the center of the marsh, so at once proceeded to the spot. The bird rose when I was within a few yards of it, and to my delight I saw the nest with two eggs. Mr. Ludwig Kumlien (1879) found this species breeding on the Greenland coast under very different conditions. He writes: I have, however, nowhere found them so very common as on the southern shores of Disko Island; at Laxbught and Fortuna Bay there must have been LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 9 many hundred pairs nesting. Their breeding place was an inaccessible cliff about half a mile from the seashore. The greater number of the birds nesting bere were in the plumage described in Doctor Coues’s monograph of the Laridae as the nearly adult plumage; but there were also a good many birds that were unicolored blackish brown all over, but with the long vertically twisted tail feathers. That these were breeding I think there can be no doubt, as I saw them carrying food up to the ledges on the cliff, for the young I suppose. Eggs—TYhe Pomarine jaeger lays two or three eggs to a set, usually the former. They are said to be scarcely distinguishable from certain eggs of the parasitic jaeger or of the mew gull, but are more pointed. The shape is ovate or pointed ovate. The shell is smooth and slightly glossy. The ground color varies from “ brown- ish olive ” or “ Brussels brown” to “ olive lake” or “ dark olive buff.” They are rather sparingly spotted with “bone brown,” “ bister,” “chestnut brown,” or “snuff brown,” and occasionally with under- lying spots or blotches of various shades of drab or gray. The meas- urements of 49 eggs, in various collections, average 62 by 44 milli- meters; the eggs showing the four extremes measure 72.6 by 44.9, 68 by 48, 57.2 by 48.6, and 58.5 by 40 millimeters. 