Howler monkeys and spider monkeys

(Atelidae)

Class Mammalia

Order Primates

Suborder Anthropoidea

Family Atelidae

Thumbnail description
The largest New World monkeys, possess prehensile tails; range in color from pale blonde and light gray to black; some have completely black faces, others have pink and white facial mottling

Size
Ateles: head and body length 15–25 in (38–64 cm), tail length 20–35 in (51–89 cm), 13.2 lb (6 kg). Brachyteles: head and body length: 18–25 in (46–64 cm), tail length 23–36 in (59–92 cm), 15.4–33 lb (7–15 kg); Alouatta: head and body length 22–36 in (56–92 cm), tail length 20–35 in (51–89 cm), 8.8–22 lb (4–10 kg). Lagothrix: head and body length: 20–35 in (51–69 cm), tail length 23–28 in (59–72 cm), 12–24 lb (5.5–10.8 kg)

Number of genera, species
5 genera; 22–24 species

Habitat
Gallery forest, deciduous and semi-deciduous rainforest, some species also found in mangrove swamps or secondary forest

Conservation status
Critically Endangered: 3 species; Endangered: 3 species; Vulnerable: 5

Distribution
Mexico through Central and South America

Evolution and systematics

Mid-Miocene deposits of Colombia have yielded material assigned to the fossil genus Stirtonia, but there is little else in the way of fossil Atelidae until more recent Pleistocene fossils from caves in eastern Brazil. One of these, Caipora bambuiorum is considered to be a large juvenile with a distinctly Ateles-like crania. Another, Paratopithecus brasiliensis, is an even larger (approximately 55 lb, or 25 kg) adult, whose post-crania resembles extant Ateles and Brachyteles and some skeletal fragments found in the 1800s in the state of Minas Gerais. The crania of Paratopithecus resembles extant Alouatta, however, leading to uncertainties in interpreting such a mosaic of traits.

The Atelidae is now widely accepted as a monophyletic family, although some prior classifications included variously Pithecinae, Callicebinae, and Aotinae along with the Alouattinae and Atelinae. Alouatta has typically been distinguished from the other genera, but there is still controversy over the phylogenetic relationships among the atelins. Morphological analyses group Ateles and Brachyteles in a clade separate from Lagothrix, while molecular data suggests a Brachyteles/Lagothrix clade. Indeed, the karyotypes of these two genera are similar (2n=62 chromosomes), and differ from Ateles, which varies from 2n=32 to 2n=34 chromosomes.

Like many other primates, the Atelidae has recently undergone a major taxonomic revision. The result, for the most part, has been the splitting of previously recognized subspecies into distinct species, and in the case of Lagothrix, splitting the yellow-tailed woolly monkey, L. flavicauda, into a separate genus, Oreonax flavicauda. In many cases, the reclassifications have been prompted by new molecular analyses, but re-examinations of museum specimens have also played a role.

Physical characteristics

The Atelidae are the largest New World primates. In Alouatta and Lagothrix, females are much smaller than males, while in Ateles and Brachyteles, males and females are more similar to one another in body size. All of the Atelidae possess prehensile tails, which are bare on the distal underside. The tails are very sensitive, and are used for grasping much like an extra hand. All of the atelids also have 36 teeth, with a dental formula of (I2/2 C1/1 P3/3 M3/3). The relative size

and shapes of their teeth, as well as their jaws and chewing muscles, vary with their respective feeding adaptations.

Atelidae range in color from pale buff or gray (Brachyteles) to dark black (some Alouatta and Ateles). Some species of Alouatta are sexually dichromatic in body color. Alouatta, Lagothrix, and Brachyteles arachnoides have completely black faces. Oreonax has a lighter muzzle, many species of Ateles have distinctly paler eye patches, and Brachyteles hypoxanthus has pink and white patches of skin in variable patterns on the face. The latter also exhibit variation in pigment on the scrotum.

In both Ateles and Brachyteles females, the clitoris is pendulous and elongated. Male Brachyteles also have relatively large testes. Both of these genera also have long hooked fingers, and long limbs and tails relative to their bodies. Lagothrix and Alouatta have more compact bodies and limbs, and relatively shorter tails. Lagothrix travels by suspensory locomotion much less than Ateles or Brachyteles, but is faster and more agile than Alouatta. Alouatta possesses an enlarged hyoid bone, which contributes to the projection of long distance roars. Alouatta also has an elongated hindgut associated with the slow rate of food passage.

Distribution

The family is found only in Central and South America. Howler monkeys (genus Alouatta) have the most extensive distribution, which ranges from southern Mexico in the north to northern Argentina in the south. Spider monkeys (genus Ateles) occur from southern Mexico, through Central America and the Amazon. Woolly monkeys (genus Lagothrix) are restricted to the Amazon, with the recently recognized genus Oreonax, or the yellow-tailed woolly monkey, found only in the northeastern montane cloud forest of Peru. Muriquis (genus Brachyteles) are found only in the southeastern Atlantic forest of Brazil.

Howler monkeys occur sympatrically with one, and sometimes two of the other genera. Alouatta is the only genus in this family that occurs sympatrically with Brachyteles. In some regions in the Amazon, Alouatta, Ateles, and Lagothrix are found together.

Habitat

All species are arboreal, although Alouatta, Ateles, Brachyteles, and Lagothrix have been observed to descend to the ground to eat, drink, play, and travel for brief periods. With the exception of Oreonax, they are found in a wide variety of habitats. Alouatta and Brachyteles in particular are still found in disturbed and secondary patches of forest, where their ability to consume large quantities of leaves may contribute to their persistence. Lagothrix and Ateles are more

restricted to primary tropical rainforest, although some species of Ateles are also found in semi-deciduous and degraded forest patches.

Atelids appear to prefer the upper canopy, but they also use their tails to exploit foods at lower levels in the forest. They tend to rest on secure branches, but are adept at feeding from terminal branches and lianas.

Behavior

All species live in multimale, multifemale groups, although one-male, multifemale groups of Alouatta are also common. In the three well-known atelin genera (Ateles, Brachyteles, and Lagothrix), males are philopatric, while females disperse from their natal groups to join other groups of males. In Alouatta, both males and females disperse from their natal groups, usually to establish new troops. Female red howler monkeys (Alouatta seniculus) may be retained in their natal troops, while males sometimes disperse in pairs to establish new troops together.

Alouatta are renowned for their loud, long-distance roars. Neighboring troops engage in howling displays, often, but not exclusively, at the boundaries of their ranges. Howler monkey calls can be heard by humans as far as 0.6 mi (2 km) away. Ateles and Brachyteles have large repertoires of vocalizations, including a long-distance call that resembles a horse's whinny, and an alarm call that resembles a dog's bark. They also have softer, less far ranging "chuckles," which may help them to maintain contact with one another while they are spread out during travel and foraging.

None of the species defend exclusive territories, although encounters between groups, especially of Alouatta, can be highly aggressive. In Lagothrix, Ateles, and Brachyteles, large neighboring groups exploit large, overlapping home ranges. Home range overlap is greater at high population densities. Home range sizes vary from 25 acres (10 ha) in Alouatta to over 2,220 acres (900 ha) in woolly monkeys and muriquis living in continuous forest in the Amazon and southern Atlantic forest, respectively.

All of the genera are primarily diurnal. Observers that leave the monkeys asleep at dusk often find them in the exact same positions the next morning. Activity patterns differ with climate and season. In general, bouts of morning traveling and feeding are followed by mid-day siestas, and then more traveling and feeding before the groups settle down for the night. Howler monkeys devote up to 70% of their daylight hours to resting, and travel shorter distances each day than the other genera. Spider monkeys and muriquis devote about half of the day to resting, and can travel up to 1.9 mi (3 km) in a day. Woolly monkeys are intermediate in their resting and traveling habitats, at least at the sites where they have been studied to date.

Feeding ecology and diet

All species show clear preferences for ripe fruit when it is available, and supplement their diets with various quantities of leaves. Woolly monkeys at La Macarena, Colombia also consume substantial quantities of insects. Other foods, such as flowers and nectar, and new shoots are eaten when available, while bark and bamboo supplement diets during periods of preferred food scarcity.

Howler monkeys are by far the most folivorous, but the proportion of leaves in their diets varies greatly by habitat. Sympatric species exhibit considerable overlap in diet, feeding on many of the same fruit, leaf, and flower species, sometimes from the same trees or lianas. There are interesting parallels in the proportion of fruits versus leaves in the annual diets of sympatric spider monkeys and howler monkeys, on the one hand, and those of sympatric muriquis and howler monkeys, on the other hand. In each pair, the howler monkeys are substantially more folivorous than either spider monkeys or muriquis.

There is also extensive intraspecific variation in diets. For example, populations of southern muriquis inhabiting disturbed or regenerating forest fragments devote up to 70% of their feeding time to leaves, whereas those inhabiting undisturbed, continuous forest devote up to 70% of their feeding time to fruits. The latter also utilize much larger home ranges, and occur at much lower population densities. Whether low population density permits them to maintain a more frugivorous diet by expanding their home range, or whether undisturbed forests have more abundant fruit is not yet known.

All genera possess prehensile tails, which permit them to feed for long periods of time in suspended postures. Secured by their tails, they can access foods close to the ground or from plants and branches that are too small or flimsy to support their body weights. Their tails also free up their hands, which they can use to sort foods and bring them to their mouths. The atelins also travel by suspensory locomotion, using their arms and tails to swing through the canopy. Suspensory locomotion permits them to travel long distances rapidly, and may contribute to their ability to monitor dispersed patches of preferred fruits. Howler monkeys are quadrupedal, traveling much shorter distances more slowly than the atelins.

Reproductive biology

Females exhibit proceptive behaviors, which in Brachyteles and Ateles are now known to correspond with their ovarian cycles. Males frequently inspect the genitalia of females by visual and olfactory means. Copulations sometimes occur with the females sitting, instead of standing as occurs in most other primates.

Female atelins typically mate with multiple partners, although the degree to which single males monopolize access to females and exclude other males from mating varies greatly. In multimale troops of red howler monkeys, the alpha male can account for 100% of all fertilizations, resulting in the genetic equivalent of a single-male troop. In woolly monkeys

and spider monkeys, high-ranking males account for most observed copulations. In muriquis, females mate with multiple partners, often one right after the other, and there is no evidence that males compete overtly with one another for access to mates.

There is no evidence of paternal or allo-parental care among the atelins. However, male howler monkeys will sometimes carry infants or position themselves between infants and extra-troop males, which may threaten infants in their efforts to take over female troops.

Reproductive seasonality varies widely across species and populations of the same species, with a tendency for more seasonal reproduction in more seasonal habitats. It is unclear whether reproductive seasonality reflects maternal condition at the time of conceptions, or the availability of food at the time of weaning. The tendency is for births to occur in the dry season when preferred fruits and new leaves are scarcest, and both conceptions and weaning to occur in the rainy season when preferred foods are most abundant.

Gestation length ranges from 6 months in Alouatta, to 7 months in Ateles, to 7.2 months in Brachyteles. Average inter-birth intervals range from 2 years in Alouatta to 3 years in the atelins. Age at first reproduction for females ranges from about 4 years in Alouatta to at least 9 years in Brachyteles.

Conservation status

Both species of Brachyteles, along with the recently recognized genus, Oreonax, are classified as Critically Endangered based on their highly restricted distributions, small population size, and deteriorating habitats. Brachyteles is the only genus of Atelidae endemic to the Brazilian Atlantic forest. The brown howler monkey, Alouatta guariba, is also endemic to the Atlantic forest, and is classified as Vulnerable. The status of Brachyteles hypoxanthus is probably more critical than that of B. arachnoides because the latter still retains relatively large populations in protected forest. Population estimates for Brachyteles hypoxanthus are under 500 individuals, with nearly 200 found in one small reserve in Minas Gerais. Oreonax population size is estimated at fewer than 300 individuals.

Three species are classified as Endangered (Alouatta coibensis, Ateles marginatus, and A. hybridus) and five species are classified as Vulnerable (Alouatta guariba, Ateles belzebuth, Lagothrix cana, L. lugens, and L. poeppigii). Local populations of several subspecies are also considered to be Endangered or Vulnerable. In all cases, restricted geographic distributions coupled with habitat destruction and hunting pressures contribute to the precariousness of their futures.

The large body size and large group size of atelid make them attractive prey to hunters. In addition to the toll that hunting takes on local populations, many have suffered due to habitat destruction and fragmentation. The construction of roads increases access for hunters and degrades habitats, while the cutting and burning of forest for pasture and agriculture.

Conservation efforts are widespread, and include the establishment of protected parks and reserves as well as legislation that prohibits hunting. However, enforcement of prohibitions is often impeded by insufficient funds. Conservation education efforts and international collaborations between habitat countries and nongovernmental organizations (NGOs) can be effective, but require long-term commitments at all levels.

Significance to humans

Atelidae are represented in the art and legends of the people they live nearby. Their large body size and social habits have probably always made them a source of prized meat. The large testes of Brachyteles were associated with sexual potency, and made into purses by hunters.

None of the Atelidae are considered to be agricultural pests or dangerous to humans. The docile behavior of Ateles and Brachyteles also contribute to their desirability as pets.

Species accounts

List of Species

Mantled howler monkey

Alouatta palliata

subfamily

Mycetinae

taxonomy

Mycetes palliata (Gray, 1849), Nicaragua.

other common names

None known.

physical characteristics

Black, with a "fringe" on flanks of long gold or brown hair. Backward forehead hair forms a straight crest on crown.

distribution

Mexico through Central America to western Colombia and Ecuador.

habitat

Evergreen rainforest, dry decidious forest in lowland and some mangrove forest.

behavior

Mantled howler monkeys live in cohesive, multimale, multifemale groups with 4–21 individuals. Both males and females establish dominance hierarchies. Glander found that young females become top ranking when they immigrate into troops, but achieve their highest reproductive success as older, mid-ranking troop

members. Males compete aggressively for high rank, and rarely maintain their alpha status for more than a few years. Both sexes disperse from their natal groups. Inter-troop interactions are usually aggressive and occur wherever they are within their overlapping home ranges, which vary from 25 to 148 acres (10–60 ha) in size.

feeding ecology and diet

Leaves comprise over 60% of mantled howler monkey diets. They exhibit preferences for young leaves over mature leaves, and eat fruits and flowers whenever they can. Consistent with a heavy dietary reliance on leaves, which are low in energy, mantled howler monkeys spend nearly two-thirds of their days resting, and day ranges are rarely longer than 0.6 mi (1 km).

reproductive biology

Polygamous. Alpha males have higher mating success than other males. Births occur throughout the year, but tend to be concentrated in the dry season in more seasonal habitats. Average birth intervals are just under two years, and gestation is about six mos. Females give birth to their first infants at about four years of age, similar to other species of Alouatta and younger than the other atelidae genera.

conservation status

Not listed by the IUCN, although the subspecies Alouatta palliata mexicana is classified as Vulnerable.

significance to humans

Hunted for meat.

Venezuelan red howler monkey

Alouatta seniculus

subfamily

Mycetinae

taxonomy

Simia seniculus (Linnaeus, 1766), Colombia.

other common names

English: Red howler monkey.

physical characteristics

Dark red-maroon head, back, and limbs, with lighter, more golden sides. Crown hair as runs forward to meet the forehead hair in a concave V.

distribution

South and eastern Venezuela and northwestern Brazil; may also be sympatric with Alouatta palliata.

habitat

Gallery and semi-deciduous forest, secondary forest.

behavior

Both males and females disperse, but over 20% of females may remain and breed in their natal troops. Females that remain in their natal troops reproduce earlier than females that disperse. Recruitment of daughters appears to be constrained by troop size, with four females being the usual limit. Male red howler monkeys are tolerated in their natal troops longer than male mantled howler monkeys, and may disperse more than once during their lifetimes. Troops may include more than one male, and males sometimes remain together after dispersing from their natal troops. Coalitions of males appear to be more successful at rebuffing threats from extra-troop males, and may therefore hold onto their position in female troops longer than solitary males.

feeding ecology and diet

Like other species of howler monkeys, red howler monkey diets are highly folivorous. Their day ranges are similarly short, and their home ranges similarly small compared to other atelidae genera.

reproductive biology

Polygamous. Alpha males have higher mating success than other males, and in multimale troops, the alpha male may account for 100% of the fertilizations. Births occur throughout the year, and birth intervals average just under two years. Male red howler monkeys that takeover a troop have been reported to kill infants sired by the males they have ousted.

conservation status

Not listed by the IUCN, although one subspecies, Alouatta seniculus insulanus, is classified as Vulnerable and three subspecies, A. s. amazonica, A. s. juara, and A. s. puruensis are classified as Data Deficient.

significance to humans

Hunted for meat.

Geoffroy's spider monkey

Ateles geoffroyi

subfamily

Atelinae

taxonomy

Ateles geoffroyi Kuhl, 1820, Nicaragua.

other common names

English: Black-handed spider monkey.

physical characteristics

Body coat varies in color from yellow, to red, to black, with black hands and feet. Cheek hairs stand out, and that hair on the top of the head forms a cowl that ends in a triangular crest over the brows.

distribution

Northeast and west coast of Mexico to Panama.

habitat

Evergreen rainforest, semi-deciduous forest, mangrove forest.

behavior

Multimale, multifemales groups with over 40 individuals routinely split up into smaller foraging parties and are rarely observed together. Males remain in their natal groups, and tend to associate more with one another than with females. Males have hierarchical relationships, but also affiliate more closely with one another than with females. At Barro Colorado Island, Panama, males were observed to engage in fur-rubbing behavior more commonly than females.

feeding ecology and diet

Geoffroy's spider monkeys at Santa Rosa National Park, Costa Rica prefer fruit, which comprises over 70% of their annual diet. Chapman found that they adjust the size of their feeding parties to the size of fruit patches. Day ranges average about 4,265 ft (1,300 m), within a home range of 420 acres (170 ha). They may be important seed dispersers of the fruit species they eat.

reproductive biology

Ovarian cycles last from 20 to 23 days in length. Birth intervals are about three years, and may be concentrated in more seasonal habitats.

conservation status

Not listed by the IUCN.

significance to humans

Hunted for meat.

Peruvian spider monkey

Ateles chamek

subfamily

Atelinae

taxonomy

Simia chamek (Humbolt, 1812), Peru.

other common names

English: Black-faced black spider monkey.

physical characteristics

Pelage and face is black, with a silvery genital patch and sometimes, white facial hairs.

distribution

Peru to the Rio Tapajós in Brazil.

habitat

Primary tropical rainforest.

behavior

A study of Peruvian spider monkeys (previously, Ateles paniscus chamek) at Manu National Park, Peru, emphasized the fluidity of grouping patterns and sex differences in behavior. Males associate and groom with one another more than with females, and maintain hierarchical relationships. Males are dominant over females, and spend more time traveling and less time feeding than females. Encounters between males from different groups are hostile, and involve both vocalizations and chases.

feeding ecology and diet

Peruvian spider monkeys devote up to 80% of their feeding time to fruit. They supplement their diets with young leaves and flowers, as well as occasional insects. Like other species of spider monkeys, they adjust their grouping patterns to the size of fruit patches, and travel widely between dispersed patches of fruits. This results in large home ranges, long day ranges, and very fluid grouping patterns.

reproductive biology

Polygamous. Birth intervals average about three years.

conservation status

Not listed by the IUCN.

significance to humans

Like other Atelidae, they are hunted for meat.

Southern muriqui

Brachyteles arachnoides

subfamily

Atelinae

taxonomy

Ateles arachnoides (É. Geoffroy, 1806), Brazil.

other common names

English: Woolly spider monkey; French: Atèle arachnoïde, eroïde, singe-araignèe; Spanish: Mono grande, muriki.

physical characteristics

Muriquis are distinguishable by their large body size, light pelage, elongated limbs, and prehensile tails. Southern muriquis have black faces and black genitalia, and are lacking a thumb. The canines of males are larger than those of females.

distribution

Atlantic forest within the states of São Paulo, Paraná, and probably Rio de Janeiro.

habitat

Semi-deciduous montane forest.

behavior

Behavioral data from two populations in São Paulo indicate substantial variation that is most likely related to ecological differences. At Fazenda Barreiro Rico, Milton (1985) observed a group of 7 individuals, including females and immatures. Females associated only loosely with adult males, except when a

female was sexually receptive and mated with multiple males in close succession. At Parque Estadual de Carlos Botelho, Moraes et al. (1998) described a larger group of over 20 individuals including adult males, females, and immatures that usually split up into smaller foraging parties. Low population densities at Carlos Botelho may account for the low frequency at which long-distance vocalizations are heard. Peaceful associations among group members, including adult males, seem to be an unusual behavioral feature of the genus.

feeding ecology and diet

Flexible grouping patterns allow southern muriquis to reduce competition over food, which includes primarily fruits, leaves, and flowers. In the large, continuous, more humid forest at the Parque Estadual Carlos Botelho, the majority of the diet is fruit, and home ranges may exceed 1,975 acres (800 ha). By contrast, in the smaller, drier forest at Fazenda Barreiro Rico, the diet is more seasonal and home ranges are much smaller.

reproductive biology

Polygamous. Milton (1985) described the mating patterns of one female at Fazenda Barreiro Rico. This female exhibited proceptive behavior, including a distinct "mating twitter" vocalization, and copulated with multiple males in close succession over the course of a few days. Births appear to be concentrated during the dry season months. Milton described the large quantities of ejaculate visible after copulations, which have also been observed in northern muriquis.

conservation status

Listed as Critically Endangered by the IUCN.

significance to humans

Although they are legally protected, hunters still seek adults for meat and infants as pets.

Northern muriqui

Brachyteles hypoxanthus

subfamily

Atelinae

taxonomy

Brachyteles hypoxanthus Kuhl, 1820, Bahia

other common names

English: Woolly spider monkey.

physical characteristics

Northern muriquis are born with black faces, which become dispigmented with pink or white mottling as they mature. Male testes are also variable in color and mottling. Some possess vestigial thumbs, which together with their facial mottling, distinguish the northern species from the southern one.

distribution

Atlantic forest within the states of Minas Gerais, Espírito Santo, and probably still in southern Bahia.

habitat

Semi-deciduous montane forest.

behavior

Behavioral data are available from two populations in Minas Gerais, including one long-term study initiated in 1982 at Fazenda Montes Claros, now known as the Estação Biológica de Caratinga/Reserva Feliciano Miguel Abdalla (EBC/RFMA). Strier (1999) documented an increase in one group's size from 22 to 70+ individuals over a 20 year period. Grouping patterns became more fluid as the number of group members increased, but adult males, which remain in their natal groups, routinely associate together in the same subgroups. Relationships among group members are strikingly peaceful and egalitarian.

feeding ecology and diet

Northern muriquis have highly seasonal diets corresponding to the availability of preferred fruits, flowers, and new leaves. They consume mature leaves, as well as bark and bamboo, primarily in the dry season when their preferred foods are scarce.

reproductive biology

Polygamous. Using non-invasive fecal steroid analyses, Strier and Ziegler (1997) found that females at the EBC/RFMA experienced 2–6 ovarian cycles prior to conceiving, intervals between ovulations averaged about 21 days, and gestation lasted 7.2 months. Females routinely mate with multiple partners. The mating season begins at the end of the annual dry season, with the majority of conceptions occuring during the peak of the rainy season. Births are concentrated during the dry season, and interbirth intervals average three years.

conservation status

Listed as Critically Endangered by the IUCN.

significance to humans

Although they are legally protected, hunters still seek adults for meat and infants as pets.

Gray woolly monkey

Lagothrix cana

subfamily

Atelinae

taxonomy

Simia cana (É. Geoffroy, 1812), Brazil.

other common names

English: Geoffroy's woolly monkey.

physical characteristics

Grayer, with an even darker gray head compared to the brown woolly monkey Lagothrix lagotricha, whose head is lighter in color than its body. Lowland specimens may be paler gray; in all, hands, feet, and tails are darker than the body.

distribution

Brazil, south of the Amazon and Peru, southern highlands.

habitat

Gallery, flooded, and unflooded rainforest.

behavior

Peres (1996) studied a group of 39–41 gray woolly monkeys in terre firme forest near the upper Urucu river in Amazonas, Brazil. Altogether, this group included nine adult and subadult males, 12–14 adult females with 5–8 infants, and 15–18 subadult females and juveniles. Group members spent most of their time spread out from one another, but in contrast to the fission-fusion societies of spider monkeys, their movements were not independent of one another and subgroups usually included a combination of adult males, females, and immatures. Gray monkeys use vocalizations, including a "loud neigh" to maintain contact with one another while spread out by more than 1,300 ft (400 m).

feeding ecology and diet

Gray woolly monkeys prefer fruits and flowers when these resources are available, but also eat a variety of foliage. They adjust the size of their feeding parties to the size of fruit and flower patches, and the degree to which they spread out while feeding coincides with seasonal variation in the density of fruit patches in their home range, which was estimated to exceed 2,220 acres (900 ha). Within their home range, they preferred unflooded forest to flood forest.

reproductive biology

No data are presently available from wild populations.

conservation status

Listed as Vulnerable by the IUCN.

significance to humans

A major source of meat in many areas.

Colombian woolly monkey

Lagothrix lugens

subfamily

Atelinae

taxonomy

Lagothrix lugens Elliot, 1907, Colombia.

other common names

None known.

physical characteristics

Highly variable in color and patterns, ranging from brown/black to lighter gray.

distribution

Restricted to the headwaters of the Orinoco tributaries in Colombia and Venezuela.

habitat

Lowland tropical forest

behavior

In contrast to gray woolly monkeys, the multimale, multi-female groups of Colombia woolly monkeys remain cohesive throughout the year. Males maintain hierarchical relationships, and rarely feed in the same trees with one another. Males are dominant over females, and may exclude non-lactating females and juveniles from feeding trees.

feeding ecology and diet

Like other species of woolly monkeys, including the silvery woolly monkey, Lagothrix poeppigii in Ecuador, Colombian woolly monkeys prefer fruits more than other food types. Unlike the other species, however, arthropods account for over 20% of Colombian woolly monkey diets. The inclusion of arthropods in their diet may reduce intragroup feeding competition, and therefore permit them to maintain cohesive groups instead of adjusting their grouping patterns to the size of fruit patches. At La Macarena, woolly monkeys occur sympatrically with capuchin monkeys, as well as with spider monkeys and howler monkeys. They compete for many of the same fruit patches used by these other primates, and directed more aggression toward the other species than they received.

reproductive biology

Polygamous. Matings occur throughout the year, but births at La Macarena are concentrated between August and December. Like spider monkeys and muriquis, birth intervals are three years. All males copulate with all sexually-receptive females, but high ranking males copulate more frequently than low ranking males.

conservation status

Listed as Vulnerable by the IUCN.

significance to humans

Hunted, mainly for meat.

Resources

Books

Crockett, C. M. Adaptive Radiations of Neotropical Primates. Edited by M. A. Norconk, A. L. Rosenberger, and P. A. Garber. New York: Plenum Press, 1996.

Crockett, C. M., and T. R. Pope. Juvenile Primates: Life History, Development, and Behavior, edited by M. E. Pereira and L. A. Fairbanks. New York: Oxford University Press, 1993.

Groves, C. Primate Taxonomy. Washington, DC: Smithsonian Institute Press, 2001.

Hartwig, W. C., A. L. Rosenberger, P. A. Garber, and M. A. Norconk. Adaptive Radiations of Neotropical Primates, edited by M. A. Norconk, A. L. Rosenberger, and P. A. Garber. New York: Plenum Press, 1996.

Nowak, R. M. Walker's Primates of the World. Baltimore: The Johns Hopkins University Press, 1999.

Peres, C. A. Adaptive Radiations of Neotropical Primates. Edited by M. A. Norconk, A. L. Rosenberger, and P. A. Garber. New York: Plenum Press, 1996.

Rowe, N. A Pictorial Guide to the Primates. New York: Pogomias Press, 1996.

Schneider, H., and A. L. Rosenberger. Adaptive Radiations of Neotropical Primates, edited by M. A. Norconk, A. L. Rosenberger, and P. A. Garber. New York: Plenum Press, 1996.

Strier, K. B. Faces in the Forest: The Endangered Muriqui Monkeys of Brazil. Cambridge, MA: Harvard University Press, 1999.

Sussman, R. W. Primate Ecology and Social Structure, Volume 2: New World Monkeys. Needham Heights, MA: Pearson Custom Publishing, 1999.

Periodicals

Campbell, C. J. "Fur Rubbing Behavior in Free-ranging Black-handed Spider Monkeys (Ateles geoffroyi) in Panama." American Journal of Primatology 51 (2000): 205-208.

Campbell, C. J., S. E. Shideler, H. E. Todd, and B. L. Lashley. "Fecal Analysis of Ovarian Cycling in Female Black-handed Spider Monkeys (Ateles geoffroyi)." American Journal of Primatology 54 (2001): 79-89.

Cartelle, C., and W. C. Hartwig. "A New Extinct Primate Among the Pleistocene Megafauna of Bahia, Brazil." Proceedings of the National Academy of Sciences 93 (1996): 6405-6409.

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Karen B. Strier, PhD