Old World monkeys I

(Colobinae)

Class Mammalia

Order Primates

Family Cercopithecidae

Subfamily Colobinae

Thumbnail description
Medium-sized, essentially arboreal mammals with forward-facing, quite large eyes, relatively large brains and a quadrupedal pattern of locomotion involving grasping hands and feet

Size
Average body weights range from 9 lb 13 oz (4.45 kg) to 33 lb 5 oz (15.1 kg)

Number of genera, species
10 genera; 59 species

Habitat
Essentially forest-living, but occur in a range of forest types extending from relatively open dry forest to dense evergreen tropical rainforest

Conservation status
Critically Endangered: 4 species; Endangered: 14 species; Vulnerable: 7 species; Near Threatened: 6 species; Data Deficient: 5 species

Distribution
Asia and Southeast Asia, and Africa south of the Sahara

Evolution and systematics

Higher primates (suborder Anthropoidea) include the broad-nosed monkeys of the New World (infraorder Platyrrhini) and the narrow-nosed monkeys and apes of the Old World (infraorder Catarrhini). Old World monkeys and apes, which are widely distributed in Africa, Asia, and Southeast Asia, are uniformly characterized by a dental formula of I2/2 C1/1 P2/2 M3/3. They hence differ from all New World monkeys by reduction in the number of premolars from 3 to 2 in each tooth row. All Old World monkeys and apes have trichromatic color vision comparable to that of humans. Old World monkeys (superfamily Cercopithecoidea) differ from apes (superfamily Hominoidea) in possessing in both upper and lower jaws four-cusped molars with their cusps linked in pairs to form transverse cutting ridges (bilophodonty). Moreover, all Old World monkeys possess prominent hardened sitting pads (ischial callosities) on the buttocks, which are supported by broad, roughened bony flanges (ischial tuberosities) on the pelvis. Apart from gibbons, such a development is lacking in apes. Old World monkeys (family Cercopithecidae) are divided into two main groups, leaf-monkeys (subfamily Colobinae) and cheek-pouched monkeys (subfamily Cercopithecinae). Defining features of these two subfamilies reflect feeding habits. Whereas all cercopithecine monkeys are characterized by possession of cheek pouches for temporary storage of food, all leaf-monkeys have a complex stomach. The complex stomach, which is unique among primates, is subdivided into 4 distinct compartments (cardiac pouch, gastric sac, gastric tube and pyloric chamber). The complex stomach represents an adaptation for housing symbiotic bacteria to permit digestion of plant cell walls in a typically leaf-rich diet. Available evidence indicates that colobine monkeys have somewhat lower basal metabolic rates than cercopithecine monkeys, and this may be connected with their leaf-eating specialization. Leaf-monkeys also differ consistently and obviously from cheek-pouched monkeys in skull morphology: the distance between the eye sockets (interorbital distance) is large in colobines and small in cercopithecines.

Although there seems to be a fairly clear distinction between leaf-monkeys living in Asia and Southeast Asia and those living in sub-Saharan Africa, this is not recognized in any formal subdivision (e.g., as tribes) in current classifications.

Numerous Old World monkeys show some form of sexual dimorphism, in which males and females differ in features not directly related to reproduction. Males and females of a species can differ markedly in general appearance, in overall body size and/or in the size of the canine teeth, although these features can vary somewhat independently. As a general rule, sexual dimorphism is less pronounced in leaf-monkeys than in cheek-pouched monkeys. Nevertheless, there are some quite striking examples of dimorphism in leaf-monkeys as well. The most outstanding example of sexual dimorphism in all three aspects is provided by the proboscis monkey (Nasalis larvatus), in which males weigh more than twice as much as females, have significantly bigger canine teeth and exhibit

more extreme development of the prominent nose that characterizes this species.

Although morphological evidence is equivocal, chromosomal and molecular evidence indicates that the African and Asian groups of leaf-monkeys are both monophyletic, each being derived from a separate common ancestor after the leaf-monkeys diverged from the cheek-pouched monkeys. The African leaf-monkeys, which can be referred to collectively as colobus monkeys, include 15 species belonging to 3 genera (Colobus, Piliocolobus, and Procolobus). All of these monkeys were originally included in the single genus Colobus, but it is now recognized that their diversity merits separation at the generic level. Nevertheless, the Asian leaf-monkeys are undoubtedly more diverse both numerically and morphologically, and the 44 species are allocated to 7 different genera. Some of the Asian leaf-monkeys are generally labeled langurs and can be allocated to 3 genera (Presbytis, Semnopithecus, and Trachypithecus). The remaining Asian leaf-monkeys all show some kind of special modification of the nose and can be collectively labeled "odd-nosed leaf-monkeys." They can be allocated to four different genera: Nasalis, Pygathrix, Rhinopithecus and Simias.

The early fossil history of the Old World monkeys is poorly known. Early Miocene deposits of Africa, dated at about 20 million years ago (mya), have yielded Prohylobates and Victoriapithecus, both possessing bilophodont molar teeth. These early fossil forms were originally known exclusively from isolated teeth and jaw fragments. This is still the case for Prohylobates, but a fairly complete skull and parts of the postcranial skeleton are known for Victoriapithecus. As a result, it is known that this genus was characterized by possession of ischial tuberosities on the pelvis and by a short interorbital distance. It is unclear whether Victoriapithecus is specifically related to modern cheek-pouched monkeys, as might be suggested by the small interorbital distance, but there is certainly no trace as yet of an early relative of leaf-monkeys. It is not until the late Miocene and the Pliocene (less than 10 mya) that Old World monkeys become relatively well documented in the fossil record. By that stage, it is certainly possible to distinguish between colobines (relatives of leaf-monkeys) and cercopithecines (relatives of cheek-pouched monkeys). Skulls of colobine monkeys are comparatively common in Pliocene and Pleistocene deposits of northern and sub-Saharan Africa (e.g., Libypithecus, Paracolobus, and Cercopithecoides). In southern Europe the late Miocene leaf monkey Mesopithecus is documented by several skulls and almost all elements of the skeleton, and the Pliocene genus Dolichopithecus is also well documented. Furthermore, partial jaws and isolated teeth from late Miocene deposits in Pakistan have been allocated to the modern genus Presbytis as the species Presbytis sivalensis.

Physical characteristics

In the head, the eyes are always directed directly forwards and the snout is typically relatively short. As is the rule for higher primates, a rhinarium (a naked, moist area of skin around the nostrils that is present in most mammals) is always

completely absent. The nostrils are relatively close-set and typically downward-pointing (with the notable exception of the Mentawai Islands snub-nosed leaf-monkey Simias concolor), and in some species the nose is prominently developed. Cheek pouches are never present. As in all other Old World monkeys and apes, the dental formula is I2/2 C1/1 P2/2 M3/3. The canine teeth are typically large, stabbing teeth (although generally less prominent than in cheek-pouched monkeys), and the rear edges of the upper canines are honed against the leading edges of the anterior premolars in the lower jaw. In both upper and lower jaws, all molar teeth are bilophodont. Colobine monkeys typically walk and run quadrupedally in the trees and, in some cases, on the ground. In the trees, they are typically agile climbers. In contrast to cheek-pouched monkeys, the legs are typically somewhat longer than the arms. In the hand, the thumb is generally reduced, and in the colobus monkeys it is virtually vestigial. Fine manipulative actions of the hand are thus largely precluded. Well-developed hardened sitting pads (ischial callosities) are present on the buttocks, and these are supported by broad, roughened bony flanges (ischial tuberosities) on the pelvis. Reflecting the predominance of arboreal habits, the tail is usually relatively long, although it is reduced to a short appendage in some species, for example in the snub-nosed leaf-monkey.

In many species, coloration of the body fur is relatively inconspicuous or even cryptic, generally being darker dorsally and paler ventrally. In several species, infants have a distinctive coloration. The face is usually virtually naked, although there is occasionally tufts of hair on the cheeks and/or chin. Body size ranges from the olive colobus (Procolobus verus), with a head and body length a 19.0 in (48.0 cm) for males and 18.5 in (46.5 cm) for females, and a tail length of 22.5 in (56.0 cm) for males and 23 in (57.5 cm) for females, to the proboscis monkey (Nasalis larvatus), with a head and body length of 30 in (74.5 cm) for males and 25 in (62.0 cm) for females, and a tail length of 26.5 in (66.5 cm) for males and 23 in (57.5 cm) for females. Body mass ranges from 10 lb 6 oz (4.7 kg) for males and 9 lb 4 oz (4.2 kg) for females in the olive colobus (Procolobus verus) to 45 lb (20.4 kg) for males and 21 lb 10 oz (9.8 kg) for females in the proboscis monkey (Nasalis larvatus).

Distribution

In contrast to cheek-pouched monkeys of the subfamily Cercopithecinae, the leaf-monkeys predominantly occur in Southeast Asia, where they are very widely distributed. The only colobine monkeys to occur in Africa are the colobus monkeys (genera Colobus, Piliocolobus, and Procolobus), although they are quite widely distributed south of the Sahara. The remaining seven genera (Nasalis, Presbytis, Pygathrix, Rhinopithecus, Semnopithecus, Simias, and Trachypithecus) are restricted to Asia and Southeast Asia.

Habitat

Leaf-monkeys are essentially forest-living, but they occur in a wide range of forest types, including relatively open dry forest, bamboo jungle, gallery forest, swamp forest, mangrove forest, and dense evergreen tropical rainforest.

Behavior

All members of the subfamily Colobinae are diurnal and most species are arboreal in habits. In all cases, locomotion is typically quadrupedal, although suspensory behavior is also quite common during arboreal feeding. Gregarious social groups that move around and feed as relatively cohesive units are formed by all species, but these vary from multi-male troops through one-male troops to a few rare cases of monogamy. In some species that exhibit one-male groups, surplus males form bachelor male groups. Moreover, there are certain species in which individual groups temporarily combine to form larger bands. In most species, females tend to stay in their natal groups, whereas males migrate at round the time of sexual maturity. However, there are exceptions. For example, in guerezas (genus Colobus), males migrate between groups, whereas in red colobus (genus Piliocolobus) it is the females that migrate.

Feeding ecology and diet

As is indicated by their name, leaf-monkeys feed predominantly on relatively low-energy leaves and other plant parts, although many species show a preference for relatively nutritious young leaves. The bilophodont teeth that characterize all Old World monkeys probably represent an adaptation for mastication of resistant material such as leaves, so it seems likely that the common Old World ancestor of both cheek-pouched monkeys (subfamily Cercopithecinae) and leaf-monkeys (subfamily Colobinae) was at least to some extent folivorous. However, uniquely among primates, colobine monkeys also possess a complex, four-chambered stomach that permits them to digest plant cell wall material with the aid of symbiotic bacteria. Despite this fundamental adaptation for digestion of resistant plant parts, there is considerable variation in diet among colobine monkeys, and some of them have become specialized for feeding on seeds rather than leaves (e.g., Colobus satanas).

Reproductive biology

Generally polygynous. Single births are typical, although twins are born very occasionally, and two teats (mammae) are consistently present in the chest region. All species have a

menstrual cycle lasting approximately a month and marked by externally visible menstrual bleeding. In contrast to cheek-pouched monkeys, females generally lack a conspicous sex skin in the genital region that changes in coloration and size over the course of the ovarian cycle. The only exceptions are the olive colobus monkey (Procolobus verus), in which females have a moderately developed sex swelling, and some species of red colobus (Procolobus preussi), in which the sex swelling is enormous. Subadult red and olive colobus males also have a "perineal organ," which mimics the female's sexual swelling. Placentation is of a highly invasive hemochorial type. The gestation period is even longer than in cheek-pouched monkeys, varying between 195 days and 212 days for few species for which data are available.

Conservation status

Four species are Critically Endangered (Piliocolobus rufomitratus, Rhinopithecus avunculus, Trachypithecus delacouri, and Trachypithecus poliocephalus), 14 are Endangered (Nasalis larvatus, Presbytis comata, Piliocolobus badius, Piliocolobus kirkii, Piliocolobus pennantii, Pygathrix nemaeus, Pygathrix nigripes, Rhinopithecus bieti, Rhinopithecus brelichi, Simias concolor, Trachypithecus auratus, Trachypithecus geei, Trachypithecus pileatus, and Trachypithecus vetulus), seven are Vulnerable (Colobus satanas, Colobus vellerosus, Presbytis potenziani, Piliocolobus gordonorum, Rhinopithecus roxellana, Trachypithecus francoisi, and Trachypithecus johnii), and six are Near Threatened (Colobus polykomos, Presbytis femoralis, Presbytis melalophos, Presbytis thomasi, Procolobus verus and Semnopithecus entellus). Five species are listed as Data Deficient (Presbytis fredericae, Presbytis frontata, Presbytis hosei, Trachypithecus laotum, and Trachypithecus villosus).

Significance to humans

Leaf-monkeys are commonly hunted for food (bushmeat) in Asia, Southeast Asia, and Africa, although they are sometimes protected by local taboos in parts of Southeast Asia, as is the case with the northern plains gray langur (Semnopithecus entellus) in India. Despite the fact that they are just as closely related to humans as the cheek-pouched monkeys (subfamily Cercopithecinae), monkeys in the subfamily Colobinae have rarely been used in biomedical research because they are relatively difficult to maintain in captivity.

Species accounts

List of Species

Mantled guereza

Colobus guereza

subfamily

Colobinae

taxonomy

Colobus guereza Rüppell, 1835, Ethiopia. The genus Colobus originally contained all colobus monkeys, but it is now restricted to the black-and-white colobus monkeys, some of which are known as guerezas. Eight subspecies of the mantled guereza can be recognized.

other common names

English: Mantled black-and-white colobus; French: Guéréza; German: Guereza.

physical characteristics

Fur black dorsally and ventrally, with a starkly contrasting U-shaped mantle of white fur descending from the shoulders and running across the lower back. The face is black and framed with a fringe of white hair. The end of the tail is white, with the length of the white region varying between subspecies. There is moderate sexual dimorphism in body size. Head and body length: 24.5 in (61.5 cm) for males and 23 in (57.5 cm) for females; tail length: 26.5 in (66.5 cm) for males and 27.5 in (68.5 cm) for females. Body mass: 29 lb 12 oz (13.5 kg) for males and 20 lb 5 oz (9.2 kg) for females.

distribution

Extensive range from Nigeria and Cameroon in the west, eastwards through the northern Democratic Republic of Congo into southern Sudan and Ethiopia, western Uganda and isolated areas in Kenya and northern Tanzania.

habitat

Inhabits primary and secondary rainforest, gallery forest and wooded grassland, including some forested areas with a prolonged dry season.

behavior

Diurnal and arboreal. Typically live in relatively small one-male social groups containing less than a dozen individuals, but some multimale groups have been reported. Groups show conspicuous territorial behavior. Males migrate from the natal group on reaching maturity.

feeding ecology and diet

Primarily eats leaves, but supplements its diet with fruits. Diet includes a large proportion of mature leaves, and there is commonly heavy concentration on a few tree species as sources of leaves.

reproductive biology

Polygynous. Births are typically single and occur year-round. Young infants are commonly passed around among females other than the mother, and also carried by them, even quite soon after birth. This species has been little studied in captivity, so basic reproductive features such as the gestation period remain unknown.

conservation status

Not threatened.

significance to humans

Frequently hunted for bushmeat.

Western red colobus

Piliocolobus badius

subfamily

Colobinae

taxonomy

Piliocolobus badius (Kerr, 1792), Sierra Leone. Red colobus monkeys were long included in the genus Colobus, but they are sufficiently distinctive to merit the separate genus Piliocolobus. Three subspecies of the western red colobus can be recognized.

other common names

French: Colobe bai, colobe ferrugineux; German: Roter Stummelaffe; Spanish: Colobo herrumbroso occidental.

physical characteristics

Fur black or dark gray dorsally and contrastingly bright red ventrally. The cheeks and the lower parts of the limbs are also bright red. There is relatively little sexual dimorphism in body size; males are only marginally bigger than females. Head and body length: 23 in (57.0 cm) for males and 21 in (53.0 cm) for females; tail length: 26.5 in (66.5 cm) for males and 26.5 in (66.5 cm) for females. Body mass: 18 lb 7 oz (8.36 kg) for males and 18 lb 2 oz (8.21 kg) for females.

distribution

Originally widely distributed in West Africa, from the coast of Senegal to Ghana.

habitat

Inhabits primary and secondary rainforest, gallery forest and wooded grassland, often occurring together with mantled guerezas. Prefers rainforest providing young leaves throughout the year.

behavior

Diurnal and arboreal. Typically live in moderately sized multi-male groups. Groups lack conspicuous territorial behavior. Unusually among Old World monkeys, females migrate from the natal group on reaching maturity.

feeding ecology and diet

Predominantly eat leaves, but also consume appreciable quantities of flowers, shoots and fruits. Feed selectively, exhibiting a marked preference for young leaves.

reproductive biology

Polygynous. Births are typically single and occur year-round. In contrast to guerezas, young infants are never held or carried by females other than the mother. Little-studied in captivity, but the gestation period has been reported to be 198 days.

conservation status

Listed as Endangered; one subspecies, P. b. waldronae is believed extinct.

significance to humans

Frequently hunted for bushmeat.

Olive colobus

Procolobus verus

subfamily

Colobinae

taxonomy

Procolobus verus (van Beneden, 1838), Africa. This is the only species in the genus Procolobus and no subspecies are recognized. The olive colobus was originally included in the genus Colobus along with all other colobus monkeys, but several distinctive features (such as the sexual swelling of females) justify its classification in a separate genus.

other common names

English: Green colobus; French: Colobe vert, colobe de van Beneden; German: Grüner Stummelaffe; Spanish: Colobo verde.

physical characteristics

This is the smallest species in the subfamily Colobinae. Fur dull olive-brown dorsally and light gray to white ventrally. The face is framed with gray hair and there is a low crest of hair along the midline of the head. There is only mild sexual dimorphism in body size. Head and body length: 19.0 in (48.0 cm) for males and 18.5 in (46.5 cm) for females; tail length: 22.5 in (56.0 cm) for males and 23 in (57.5 cm) for females. Body mass: 10 lb 6 oz (4.7 kg) for males and 9 lb 4 oz (4.2 kg) for females.

distribution

Range extends from Sierra Leone to eastern Nigeria, with some intervening gaps.

habitat

Occupies a range of habitats, including evergreen rainforest, swamp forest and even dry deciduous forest.

behavior

Diurnal and arboreal. Typically live in small unimale groups with less than a dozen members. It is possible that females migrate from the natal group on reaching maturity, which would make this species another exception among Old World monkeys.

feeding ecology and diet

Food is taken from a large number of different tree species. Approximately two thirds of the diet consists of young leaves, but mature leaves, seeds, flowers and fruits together make up the rest.

reproductive biology

Generally polygynous. Births are typically single. There are restricted mating and birth seasons. The species is unique among higher primates in that infants are carried in the mother's mouth. Olive and red colobus are also unusual among colobine monkeys in that females exhibit a moderate-sized sexual swelling around the time of ovulation. The species has been little studied in captivity, so basic reproductive features such as the gestation period are unknown.

conservation status

Listed as Lower Risk/Near Threatened.

significance to humans

Frequently hunted for bushmeat.

Banded leaf-monkey

Presbytis melalophos

subfamily

Colobinae

taxonomy

Presbytis melalophos (Raffles, 1821), Sumatra, Indonesia. This species was originally combined with two forms that are now regarded as separate species: Presbytis femoralis and Presbytis siamensis. Following separation from these two species, the more narrowly defined Presbytis melalophos includes three subspecies.

other common names

English: Mitered leaf-monkey, Sumatran surili; French: Semnopithèque mélalophe; German: Roter Langur; Spanish: Langur de cresta.

physical characteristics

There is considerable variation in coat coloration between subspecies. Fur ranges from off-white/gray through reddish orange to chocolate dorsally and from white through cream to pale orange ventrally. There is relatively little sexual dimorphism in body size, with males being only slightly bigger than females. Head and body length: 19.5 in (49.0 cm) for males and 20 in (49.5 cm) for females; tail length: 28.5 in (71.0 cm) for males and 28.5 in (71.0 cm) for females. Body mass: 14 lb 8 oz (6.59 kg) for males and 14lb 4 oz (6.47 kg) for females.

distribution

Restricted to the southern part of Sumatra.

habitat

Primarily inhabits primary lowland rainforest, but also occurs in plantations and forest subject to logging.

behavior

Diurnal and arboreal. Social groups are variable in composition. The species commonly lives in relatively small one-male groups, but larger multi-male groups also occur. Home ranges overlap and no overt territorial behavior is shown. As is typical for most Old World monkeys, males migrate from the natal group at maturity, but some females also migrate.

feeding ecology and diet

Feed on items from a wide range of tree species, consuming young leaves, mature leaves, flowers, seeds and fruits. This is one of the exceptional leaf-monkey species that includes less than 50% of leaves in its diet and therefore does not fit the standard definition of "folivory."

reproductive biology

Polygynous. Births are typically single. This species has scarcely been studied in captivity, so little is known about its reproduction and the gestation period is unknown.

conservation status

Listed as Lower Risk/Near Threatened.

significance to humans

Occurs quite frequently in plantations. Frequently hunted for bushmeat.

Northern plains gray langur

Semnopithecus entellus

subfamily

Colobinae

taxonomy

Semnopithecus entellus (Dufresne, 1797), Bengal, India. This species was previously included in the genus Presbytis, but there are enough distinctive characters to justify a separate genus. Furthermore, several of the original subspecies included in the species Semnopithecus entellus are now regarded as separate species.

other common names

English: Hanuman langur, sacred langur, common langur; French: Houleman; German: Hanuman; Spanish: Langur hanuman.

physical characteristics

Fur gray to brownish gray dorsally and white to creamy white ventrally. The face and ears are black, and the face is framed by long white or pale gray hairs. Long, stiff hairs point forward from the brow ridge. Limbs are slightly darker than the rest of the body; the hands and feet are black. There is moderate sexual dimorphism in body size. Head and body length: 25.5 in (64.0 cm) for males and 23.5 in (58.5 cm) for females; tail length: 36.5 in (91.0 cm) for males and 34.5 in (86.0 cm) for females. Body mass: 28 lb 11 oz (13.0 kg) for males and 21 lb 13 oz (9.9 kg) for females.

distribution

Pakistan and India, between the Godavari and Krishna Rivers in the south and the Ganges River in the north.

habitat

Occurs in a wide range of forest types, from dry, thorny scrub forest to evergreen tropical rainforest.

behavior

Diurnal and semi-arboreal. Although arboreal activity is common, much time is spent on the ground, and this is one of the most terrestrial species among the leaf-monkeys. Patterns of social organization are notably variable. In some areas, northern plains gray langurs live in one-male groups, with surplus males forming bachelor groups. Violent takeovers of one-male groups by males from bachelor groups are quite common. In other cases, however, multi-male social groups are formed and such violent upheavals are lacking. This langur species is renowned for the occurrence of infanticide, which has been observed quite frequently in association with male takeovers. Typically, males emigrate from their natal groups on reaching maturity.

feeding ecology and diet

Leaves (particularly mature leaves) form the largest component in the diet, but buds, flowers and fruits are also eaten. In addition, animal prey, plant exudates and various other items are also consumed occasionally. As leaves make up less than 50% of the diet, this species does not in fact meet the standard definition of "folivory."

reproductive biology

Variable mating system (polygyny, promiscuity). Single births are typical. Births often occur throughout the year, but there is a confined birth season in areas with marked seasonality in rainfall. Females do not have sexual swellings, but they display receptivity around the time of ovulation by means of behavioral signals (behavioral estrus). Gestation period 212 days.

conservation status

Listed as Lower Risk/Near Threatened.

significance to humans

In many regions, this species is protected from harm by local custom, and food is often provided, particularly in the form of offerings at temple sites. One of the common names of this species is derived from the Hindu monkey-god Hanuman.

Silvery leaf-monkey

Trachypithecus cristatus

subfamily

Colobinae

taxonomy

Trachypithecus cristatus (Raffles, 1821), Sumatra, Indonesia. Originally included in the genus Presbytis as the species Presbytis cristata. Two subspecies can be recognized.

other common names

English: Silvery lutung, silvered langur; German: Haubenlangur.

physical characteristics

Fur brownish gray to black dorsally and pale gray ventrally. A silvery appearance results from the fact that the hairs on the back have gray or yellowish tips. There is a crest of long hairs down the midline of the head, although its prominence differs between the two subspecies. There is mild sexual dimorphism in body size. Head and body length: 22 in (55.5 cm) for males and 20 in (50.5 cm) for females; tail length: 29.5 in (73.5 cm) for males and 28 in (70.0 cm) for females. Body mass: 14 lb 9 oz (6.61 kg) for males and 12 lb 11 oz (5.76 kg) for females.

distribution

Widely distributed in Southeast Asia, occurring along the west coast of the Malayan peninsula as well as on Borneo, Sumatra, the Natuna Islands, Bangka, Belitung, and various islands in the Riau Archipelago.

habitat

Occurs in a wide range of forest types, including primary and secondary rainforest, gallery forest and mangrove forest.

behavior

Diurnal and arboreal. Live in one-male groups. There is no clear-cut territorial behavior. All males and some females migrate from their natal groups on reaching maturity.

feeding ecology and diet

Diet consists predominantly of leaves, supplemented by shoots and fruits. Food items are taken from a wide range of tree species.

reproductive biology

Polygynous. Typically gives birth to a single infant. The infant is bright orange in color for the first 3 months of life and is passed among, and carried by, adult females other than the mother. The species has rarely been kept in captivity, so basic reproductive features such as the gestation period remain unknown.

conservation status

Not threatened.

significance to humans

Often found in plantations. Frequently hunted for bushmeat.

Proboscis monkey

Nasalis larvatus

subfamily

Colobinae

taxonomy

Nasalis larvatus (Wurmb, 1787), Indonesia. This is now the only species in the genus Nasalis, and no subspecies are recognized. The species Simias concolor has sometimes been included in the genus Nasalis, but it is sufficiently distinctive to deserve its own genus.

other common names

French: Nasique; German: Nasenaffe; Spanish: Mono narigudo.

physical characteristics

This is the largest species in the subfamily Colobinae. Fur reddish orange on the crown and back and grayish white ventrally. The fur on the shoulders, neck and cheeks is pale orange. The legs and the tail are grayish white. In males, the penis is bright red in color, contrasting with the black scrotum. Both sexes have a prominent nose, but there is marked sexual dimorphism in that the nose is particularly long and drooping in males, whereas it is shorter and forward-pointing in females. Sexual dimorphism in body size is also very pronounced, with adult males weighing more than twice as much as adult females. Head and body length: 30 in (74.5 cm) for males and 25 in (62.0 cm) for females; tail length: 26.5 in (66.5 cm) for males and 23 in (57.5 cm) for females. Body mass: 45 lb (20.4 kg) for males and 21 lb 10 oz (9.8 kg) for females.

distribution

Occurs throughout Borneo, wherever suitable forest habitat is available.

habitat

Occurs in a variety of habits, including lowland rainforest, gallery forest, peat swamp forest and mangrove forest.

behavior

Diurnal and essentially arboreal. Individuals and groups have been observed swimming across rivers and even in the sea near the coast. Typically form one-male social groups, with surplus males living in bachelor groups. Individual one-male groups sometimes combine with other groups temporarily. Groups do not show clear-cut territorial behavior.

feeding ecology and diet

Feeds predominantly on leaves, but also eats flowers, fruits (mostly unripe), seeds and a small amount of animal prey.

reproductive biology

Polygynous. Typically gives birth to a single infant. The species has rarely been kept in captivity and reproductive features such as the gestation period are hence unknown.

conservation status

Listed as Endangered.

significance to humans

Quite often hunted for bushmeat.

Red-shanked douc langur

Pygathrix nemaeus

subfamily

Colobinae

taxonomy

Pygathrix nemaeus (Linnaeus, 1771), Cochin-China (Indochina). Two subspecies were originally recognized in this species, but they have been raised to the rank of separate species, the other being Pygathrix nigripes. A third species, Pygathrix cinerea, was described only in 1997.

other common names

French: Rhinopithèque douc du nord; German: Nördlicher Kleideraffe; Spanish: Mono pigatrix.

physical characteristics

The douc langurs are probably the most colorful leaf-monkey species. In the red-shanked douc langur, the fur is grizzled medium gray dorsally and lighter gray ventrally. There is a fringe of black hair across the crown, and there are long, white

cheek whiskers. The eyes slant downwards towards the nose. Around the eyes and nose, the face is yellow-brown, contrasting with a distinctive white muzzle. The hands and feet are black, whereas the forearms and wrists are covered with white hair. The thighs are black, while the lower parts of the legs are reddish-brown. There is moderate sexual dimorphism in body size. Head and body length: 23.5 in (58.5 cm) for males and 24 in (60 cm) for females; tail length: 27 in (68 cm) for males and 24 in (60 cm) for females. Body mass: 24 lb 4 oz (11.0 kg) for males and 18 lb 10 oz (8.45 kg) for females.

distribution

Occurs throughout Laos and in the northern part of Vietnam.

habitat

Inhabits primary and secondary evergreen rainforest.

behavior

Diurnal and essentially arboreal. Lives in multimale groups containing up to two dozen individuals. Individuals of both sexes migrate from the natal group on reaching maturity.

feeding ecology and diet

Eats leaves, buds, flowers, fruits, and seeds from a wide variety of tree species.

reproductive biology

Polygynous. Typically have single births. Gestation period 210 days.

conservation status

Listed as Endangered.

significance to humans

Often hunted for bushmeat.

Golden snub-nosed monkey

Rhinopithecus roxellana

subfamily

Colobinae

taxonomy

Rhinopithecus roxellana (Milne-Edwards 1870), Sichuan, China. Some authors include snub-nosed monkeys in the genus Pygathrix, rather than recognizing the separate genus Rhinopithecus. Three subspecies can be recognized for the golden snub-nosed monkey.

other common names

English: Sichuan golden snub-nosed monkey; French: Rhinopithèque doré; German: Goldener Stumpfnasenaffe.

physical characteristics

This is one of the largest leaf-monkey species, second only to the proboscis monkey. Fur grayish brown with distinctive golden strands dorsally and yellowish to golden white ventrally. Crown of head dark, with a crest of short hairs. Around the eyes, the face is pale blue. The upturned nose with forward-facing nostrils, from which this species derives its common name, is located well back relative to the inflated white muzzle. Hands and feet yellowish. Males are more brightly colored than females. There is also marked sexual dimorphism in body size. Head and body length: 23.5 in (59 cm) for males and 20.5 in (51.5 cm) for females; tail length: 35 in (87.0 cm) for males and 28 in (69.5 cm) for females. Body mass: 39 lb 7 oz (17.9 kg) for males and 25 lb 9 oz (11.6 kg) for females.

distribution

Mountainous areas of central and western China, including parts of the provinces of Sichuan, Hubei, Ganssu and Shaanxi.

habitat

Lives in bamboo jungles, coniferous forests and deciduous forests up to altitudes exceeding 10,000 ft (over 3,000 m). In areas inhabited by golden snub-nosed monkeys, there is snow cover on the ground for about half the year.

behavior

Diurnal and semi-arboreal. Although these monkeys commonly feed in trees, they travel predominantly on the ground. Seasonally shifting ranges are characteristic for this species. Golden snub-nosed monkeys live in one-male social groups, with surplus males forming bachelor groups. Several groups may aggregate to form a band containing more than 200 individuals, and 2–3 such bands may temporarily join up.

feeding ecology and diet

Feed on leaves, buds, fruits and lichens.

reproductive biology

Polygynous. Single births are typical. Infants may be carried by adult females other than the mother. Gestation period 195 days.

conservation status

Listed as Vulnerable.

significance to humans

These monkeys are sometimes hunted for food.

Mentawai Island langur

Simias concolor

subfamily

Colobinae

taxonomy

Simias concolor (Miller, 1903), western Sumatra, Indonesia. This is the only species in the genus Simias. The species has sometimes been included in the genus Nasalis, but it is sufficiently distinctive to deserve its own genus. Two subspecies can be recognized.

other common names

English: Mentawai Islands snub-nosed leaf-monkey, pig-tailed snub-nosed langur, simakobu; German: Pagehstumpfnasenaffe.

physical characteristics

Fur is black or creamy buff dorsally, irrespective of species, and paler ventrally. The nose is prominently developed, but far less so than in the proboscis monkey. This species derives one of its common names from the fact that (uniquely among leaf-monkeys) the tail is very short, almost hairless and curled upwards. There is moderate sexual dimorphism in body size. Head and body length: 20.5 in (51.5 cm) for males and 20 in (50.0 cm) for females; tail length: 6 in (15.5 cm) for males and 5.5 in (14.0 cm) for females. Body mass known only for single individuals, 19 lb 5 oz (8.75 kg) for a female and 15 lb 12 oz (7.15 kg) for a female.

distribution

Restricted to the Mentawai Islands, occurring on Siberut, Sipura and the Pagai Islands, along with a few smaller islands.

habitat

Inland evergreen rainforest and swamp forest.

behavior

Diurnal and arboreal. Social organization is variable, sometimes as one-male groups (perhaps with just a single female) and sometimes as multimale groups.

feeding ecology and diet

Diet consists mainly of leaves and fruit, in a ratio of 2:1.

reproductive biology

Variable mating system (polygny, monogamy). Single births are typical. Breeding may be seasonal. No studies have been conducted in captivity, so reproductive features such as the gestation period are unknown.

conservation status

Listed as Endangered.

significance to humans

Frequently hunted for bushmeat.

Resources

Books

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Jablonski, Nina G. The Natural History of the Doucs and Snub-Nosed Monkeys. Singapore: World Scientific, 1998.

Ji, W.-Z., Zou, R.-J., Shang, E.-Y., Zhou, H.-W., Yang, S.-C. and B.-P. Tian. "Maintenance and breeding of yunnan snub-nosed monkeys (Rhinopithecus [Rhinopithecus] bieti) in captivity." In The Natural History of the Doucs and Snub-Nosed Monkeys, edited by Nina G. Jablonski, 323–335. Singapore: World Scientific, 1998.

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Kirkpatrick, R. C. "Ecology and behavior of snub-nosed and douc langurs." In The Natural History of the Doucs and Snub-Nosed Monkeys, edited by Nina G. Jablonski, 155–190. Singapore: World Scientific, 1998.

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Stewart, Caro Beth. "The colobine Old World monkeys as a model system for the study of adaptive evolution at the molecular level." In The Nonhuman Primates, edited by P. Dolhinow and A. Fuentes, 29–38. Mountain View, CA: Mayfield Pub. Co., 1999.

Struhsaker, Thomas T. The Red Colobus Monkey. Chicago: University of Chicago Press, 1975.

Struhsaker, T. T., and J. F. Oates. "Comparison of the behavior and ecology of red colobus and black-and-white colobus monkeys in Uganda: A summary." In Primate Functional Morphology and Evolution, edited by R. H. Tuttle, 103–124. The Hague: Mouton, 1975.

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Periodicals

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Wang, W., Forstner, M. J., Zhang, Y.-P., Liu, Z.-M., Wei, Y., Huang, H.-Q., Hu, H.-Q., Xie, Y.-X., Wu, D.-H., and D. J. Melnick. "A phylogeny of Chinese leaf monkeys using mitochondrial ND3-ND4 gene sequences." International Journal of Primatology 18 (1997): 305–320.

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Winkler, P., Loch, H., and C. Vogel. "Life history of hanuman langurs (Presbytis entellus): reproductive parameters, infant mortality, and troop development." Folia Primatologica 43 (1984): 1–23.

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Ziegler, T., Hodges, K., Winkler, P., and M. Heistermann. "Hormonal correlates of reproductive seasonality in wild female hanuman langurs (Presbytis entellus)." American Journal of Primatology 51 (2000): 119–134.

Robert D. Martin, PhD