text: mantled howler the mantled howler ( alouatta palliata ) , or golden - mantled howling monkey , is a species of howler monkey , a type of new world monkey , from central and south america . it is one of the monkey species most often seen and heard in the wild in central america . it takes its " mantled " name from the long guard hairs on its sides . the mantled howler is one of the largest central american monkeys , and males can weigh up to 9 . 8 kg ( 22 lb ) . it is the only central american monkey that eats large quantities of leaves ; it has several adaptations to this folivorous diet . since leaves are difficult to digest and provide less energy than most foods , the mantled howler spends the majority of each day resting and sleeping . the male mantled howler has an enlarged hyoid bone , a hollow bone near the vocal cords , which amplifies the calls made by the male , and is the reason for the name " howler " . howling allows the monkeys to locate each other without expending energy on moving or risking physical confrontation . the mantled howler lives in groups that can have over 40 members , although groups are usually smaller . most mantled howlers of both sexes are evicted from the group they were born in upon reaching sexual maturity , resulting in most adult group members being unrelated . the most dominant male , the alpha male , gets preference for food and resting places , and mates with most of the receptive females . the mantled howler is important to the rainforest ecology as a seed disperser and . although it is affected by deforestation , it is able to adapt better than other species , due to its ability to feed on abundant leaves and its ability to live in a limited amount of space . taxonomy the mantled howler belongs to the new world monkey family atelidae , the family that contains the howler monkeys , spider monkeys , woolly monkeys and muriquis . it is a member of the subfamily and genus alouatta , the subfamily and genus containing all the howler monkeys . the species name is a. palliata ; a pallium was a cloak or mantle worn by ancient greeks and romans . this refers to the long guard hairs , known as a " mantle " , on its sides . three subspecies are recognized : ecuadorian mantled howler , alouatta palliata aequatorialis , in colombia , costa rica , ecuador , panama and peru ; golden - mantled howler , alouatta palliata palliata , in costa rica , guatemala , honduras and nicaragua ; mexican howler , alouatta palliata mexicana , in mexico and guatemala . two additional subspecies of the mantled howler are sometimes recognised , but these are more generally recognised as subspecies of the coiba island howler , . however , mitochondrial dna testing of their status has been inconclusive : howler , alouatta palliata , in panama ; alouatta palliata , in panama . physical description the mantled howler 's appearance is similar to other howler monkeys of the genus alouatta except for coloration . the mantled howler is primarily black except for a fringe of yellow or golden brown guard hairs on the flanks of the body earning the common name " mantled " howler monkey . when the males reach maturity , the scrotum turns white . females are between 481 and 632 mm ( 18 . 9 and 24 . 9 in ) in body length , excluding tail , and males are between 508 and 675 mm ( 20 . 0 and 26 . 6 in ) . the prehensile tail is between 545 and 655 mm ( 21 . 5 and 25 . 8 in ) long . adult females generally weigh between 3 . 1 and 7 . 6 kg ( 6 . 8 and 16 . 8 lb ) , while males typically weigh between 4 . 5 and 9 . 8 kg ( 9 . 9 and 21 . 6 lb ) . average body weights can vary significantly between monkey populations in different locations . the brain of an adult mantled howler is about 55 . 1 g ( 1 . 94 oz ) , which is smaller than that of several smaller monkey species , such as the white - headed capuchin . the mantled howler shares several adaptations with other species of howler monkey that allow it to pursue a folivorous diet , that is , a diet with a large component of leaves . its molars have high shearing crests , to help it eat the leaves , and males have an enlarged hyoid bone near the vocal cords . this hyoid bone amplifies the male mantled howler 's calls , allowing it to locate other males without expending much energy . behavior social structure the mantled howler lives in groups . group size usually ranges from 10 to 20 members , generally 1 to 3 adult males and 5 to 10 adult females , but some groups have over 40 members . males outrank females , and younger animals of each gender generally have a higher rank than older animals . higher - ranking animals get preference for food and resting sites , and the alpha male gets primary mating rights . animals in the group are generally not related to each other because most members of both sexes leave the group before sexual maturity . grooming activity in the mantled howler is infrequent and has been shown to reflect social hierarchy , with dominant individuals grooming subordinates . most grooming activities are short and are typically females grooming infants or adult males . aggressive interactions between group members is not often observed either . however , studies have shown that aggressive interactions among group members do occur , and are probably not often observed because these interactions tend to be quick and silent . mantled howler groups that have been studied have occupied home ranges of between 10 and 60 hectares ( 25 and 148 acres ) . groups do not defend exclusive territories , but rather several groups have overlapping home ranges . however , if two groups meet each group will aggressively attempt to evict the other . on average , groups travel up to about 750 metres ( 2 , 460 ft ) each day . the mantled howler has little interaction with other sympatric monkey species but interactions with the white - headed capuchin sometimes occur . these are most often aggressive , and the smaller capuchins are more often the aggressors . however , affiliative associations between the capuchins and howlers do sometimes occur , mostly involving juveniles playing together , and at times the capuchins and howlers may feed in the same tree , apparently ignoring each other . diet the mantled howler is the most folivorous species of central american monkey . leaves make up between almost 50 % and 75 % of the mantled howler 's diet . the mantled howler is selective about the trees it eats from , and it prefers young leaves to mature leaves . this selectivity is likely to reduce the levels of toxins ingested , since certain leaves of various species contain toxins . young leaves generally have less toxins as well as more nutrients than more mature leaves , and are also usually easier to digest . mantled howler monkeys possess large salivary glands that help break down the leaf tannins by binding the polymers before the food bolus reaches the gut . although leaves are abundant , they are a low energy food source . the fact that the mantled howler relies so heavily on a low energy food source drives much of its behaviour – for example , howling to locate other groups and spending a large portion of the day resting . although leaves tend to make up the majority of the mantled howler 's diet , fruit can also make up a large portion of the diet . when available , the proportion of fruit in the diet can be as much as 50 % , and can sometimes exceed the proportion of leaves . the leaves and fruit from ficus trees tend to be the preferred source of the mantled howler . flowers can also make up a significant portion of the diet and are eaten in particularly significant quantities during the dry season . the mantled howler tends to get the water it needs from its food , drinking from tree holes during the wet season , and by drinking water trapped in bromeliads . like other species of howler monkeys , almost all mantled howlers have full three color vision . this is different from other types of new world monkeys , in which most individuals have two color vision . the three color vision exhibited by the mantled howler is believed to be related to its dietary preferences , allowing it to distinguish young leaves , which tend to be more reddish , from more mature leaves . locomotion the mantled howler is diurnal and arboreal . movement within the rainforest canopy and floor includes quadrupedalism ( walking and running on supports ) , bridging ( crossing gaps by stretching ) , and climbing . it will also sometimes leap to get to another limb . however , the mantled howler is a relatively inactive monkey . it sleeps or rests the entire night and about three quarters of the day . most of the active period is spent feeding , with only about 4 % of the day spent on social interaction . this lethargy is an adaptation to its low energy diet . it uses its prehensile tail to grasp a branch when sleeping , resting or when feeding . it can support its entire body weight with the tail , but more often holds on by the tail and both feet . a study has shown that the mantled howler reuses travel routes to known feeding and resting sites , and appears to remember and use particular landmarks to help pick direct routes to its destination . communication the mantled howler gets the name " howler " from the calls made by the males , particularly at dawn and dusk , but also in response to disturbances . these calls are very loud and can be heard for several kilometers . the calls consist of grunts and repeated roars that can last for four to five seconds each . the volume is produced by the hyoid bone — a hollow bone near the vocal cords — amplifying the sound made by the vocal cords . male mantled howlers have hyoid bones that are 25 times larger than similarly sized spider monkeys , and this allows the bone to act like the body of a drum in amplifying the calls . females also call but their calls are higher in pitch and not as loud as the males ' . the ability to produce these loud roars is likely an energy saving device , consistent with the mantled howler 's low energy diet . the roars allow the monkey to locate each other without moving around or risking physical confrontations . the mantled howler uses a wide range of other sounds , including barks , grunts , woofs , cackles and screeches . it uses clucking sounds to maintain auditory contact with other members of its group . the mantled howler also uses non - vocal communication , such as " urine rubbing " when in a social situation . this consists of rubbing the hands , feet , tail and / or chest with urine . it marks its scent by rubbing its throat on branches . lip smacking and tongue movements are signals used by females to indicate an invitation to mate . genital displays are used to indicate emotional states , and group members shake branches , which is apparently a playful activity . the mantled howler is usually indifferent to the presence of humans . however , when it is disturbed by people , it often express its irritation by urinating or defecating on them . it can accurately hit its observers despite being high in the trees . tool use the mantled howler has not been observed using tools , and prior to 1997 no howler monkey was known to use tools . however , in 1997 a venezuelan red howler ( alouatta ) was reported to use a stick as a club to hit a linnaeus 's two - toed sloth , ( didactylus ) , that was resting in its tree . this suggests that other howlers , such as the mantled howler , may also use tools in ways that have not yet been observed . reproduction the mantled howler uses a polygamous mating system in which one male mates with multiple females . usually , the alpha male the breeding opportunities , but if the alpha male is distracted , a lower - ranking male can get an opportunity to mate . and in some groups , lower - ranking males do get regular mating opportunities and do sire offspring . alpha males generally maintain their status for about 2 ½ to 3 years , during which time they may father 18 or so infants . females become sexually mature at 36 months , males at 42 months . females reaching sexual maturity are typically 42 months old by their first birth . they undergo a regular estrus cycle , with an average duration of 16 . 3 days , and display sexual skin changes , particularly swelling and color change ( from white to light pink ) of the labia minora . the copulatory sequence begins when a receptive female approaches a male and engages in rhythmic tongue flicking . the male responds with the same tongue movements before the female turns while elevating her rump , which allows for mating to begin . females apparently also use chemical signals , since males smell the females ' genitals and taste their urine . the gestational period is 186 days ; births can occur at any time of year . the infant 's fur is silver at birth , but turns pale or gold after a few days . after that , the fur starts to darken , and the infant takes on the adult coloration at about 3 months old . the infant is carried under its mother , clinging to its mother 's chest , for the first 2 or 3 weeks of its life . after that , it is carried on its mother 's back . at about 3 months the mother will usually start to push the infant off , but will still carry the infant some of the time until it is 4 or 5 months old . after the young can move on its own , the mother will carry it across difficult gaps in the trees . juveniles play among themselves much of the time . infants are weaned at 1 ½ years old at which point maternal care ends . adult females typically give birth every 19 to 23 months , assuming the prior infant survived to weaning . the mantled howler differs from other howler monkey species in that the males ' testes do not descend until they reach sexual maturity . upon reaching sexual maturity , the young monkeys are usually evicted from their natal group , although the offspring of a high - ranking female may get to stay in its natal group . however , many infants do not reach sexual maturity ; high - ranking adults sometimes harass or kill the offspring of lower - ranking monkeys to eliminate competition to their own offspring for an opportunity to remain with the group upon reaching maturity . natal emigration is performed by both sexes , with 79 % of all males and 96 % of the females leaving their original social group . when a male from outside the group the previous alpha male , he normally kills any infants so that the mothers come into estrus quickly and are able to mate with him . predators , such as cats , weasels , snakes and eagles , also kill infants . as a result , only about 30 % of mantled howler infants live more than one year . the highest reproductive success occurs in the middle - ranking females , with the alpha position lower possibly because of competitive pressures , and infant mortality appears to be lower when the timing of births in a group of females is clustered . if it survives infancy , the mantled howler 's lifespan is typically 25 years . distribution and habitat the mantled howler is native to colombia , costa rica , ecuador , guatemala , honduras , mexico , nicaragua , panama and peru . within honduras , nicaragua , costa rica and panama , the mantled howler is found in locations throughout the countries . in colombia and ecuador , it is found in a narrow corridor bordered by the pacific ocean to the west and the andes mountains to the east and also in colombia in a small area near the caribbean sea close to the panama border . in guatemala , the mantled howler is found through the central part of the country , and into southeastern mexico south of the yucatán peninsula . the mantled howler is among the most commonly seen and heard primates in many central american national parks , including manuel antonio , corcovado , monteverde and . the mantled howler lives in several different types of forest , including secondary forest and semi - deciduous forest but is found in higher densities in older areas of forest and in areas containing evergreen forest . the mantled howler is sympatric with another howler monkey species , the guatemalan black howler , a. , over a small part of its range , in guatemala and mexico near the yucatan peninsula . conservation status the mantled howler is regarded as " least concern " from a conservation standpoint by the iucn . nonetheless , its numbers may be adversely affected by rainforest fragmentation which has caused forced relocation of groups to less habitable regions . in 2011 , the primatologist joaquim studied in los biosphere reserve in veracruz , mexico , the impact due the fragmentation of populations and identified an increase in stress , especially among females , when a male from outside the group approached the area , because they felt that their offspring are being threatened . in addition , food limitation in areas of reduced surface area was forcing individuals to adapt their diet to increased food deprivation . highlighted that “ although this situation revealed up to what point individuals have the capacity for adaption , in some cases , undernourishment can lead to health problems that would make the population ” . results can be compared to humans who “ do not always eat everything which they should , for example in underdeveloped countries that have problems with malnutrition , rickets , a range of illnesses , but this does not put an end to the population , but rather provokes them to change their characteristics ” . however , the mantled howler can adapt to forest fragmentation better than other species due to its low energy lifestyle , small home ranges and ability to exploit widely available food sources . the mantled howler is important to its ecosystems for a number of reasons , but especially in its capacity as a seed disperser and , since passing through the monkey 's digestive tract appears to aid the germination of certain seeds . dung beetles , which are also seed dispersers as well as nutrient recyclers , also appear to be dependent on the presence of the mantled howler . the mantled howler is protected from international trade under appendix i of the convention on international trade in endangered species ( cites ) .