Cercocebus atys

Geographic Range

Sooty mangabeys are primarily endemic to Upper Guinea in coastal West Africa (Kingdon 1997, Santiago et al. 2005). The native range used to extend from the Casamance River in Senegal to the Sassandra/Nzo River system in Ivory Coast, but their population has been reduced and is mostly extinct today in Senegal, Guinea Bissau, and parts of Guinea (Rowe 1996, Groves 2001). Large numbers of sooty mangabeys still exist in Sierra Leone, Liberia, and western Ivory Coast (Santiago et al. 2005). Their range overlaps with that of other mangabey species (Estes 1991).

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Sooty mangabeys are primarily terrestrial and reside in valleys in primary, secondary, flooded, dry, mosaic and mangrove forests in the Guinean Forest Zone. They also inhabit gallery forests and are commonly spotted near swamp and palm forests (Kingdon 1997, Carey and Judge 2000).

The Tai National Park in southwestern Ivory Coast is the only primary forest left in West Africa, and many wild sooty mangabey groups are found and studied extensively there (Range and Noe 2002). In this park, there are two dry seasons and average rainfall is 1,830 mm. The mean temperature is 24 degrees Celsius (McGraw 1998).

Sooty mangabeys live from sea level up to 1000 m above sea leval, possibly higher in the Lome Mountains in Sierra Leone (Oates, Gippoliti, and Groves 2011).

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest

• Wetlands
• swamp swamp

• Other Habitat Features
• agricultural agricultural
• riparian riparian

Physical Description

A member of the Cercopithecinae , monkeys with cheek-pouches, sooty mangabeys are a smoky, slate-grey or brown-grey monkey with lighter white on their ventral side (Groves 2001). They are noted for their light colored facial whiskers, which have the greatest contrast in color in the eastern populations, and hands and feet of slightly darker color than the body. Their bare facial skin is mottled dark grey and pink salmon color, while the upper eyelids are white and the orbits and muzzle are more rectangular than round in outline (Kingdon 1997, Rowe 1996, Meester and Setzer 1971). Their face has a blackish muzzle and their ears are a similar color to their muzzle. Enlargement of the second premolar (P4) relative to the first molar separates the sooty mangabey’s dentition from other closely related species (Daegling et al. 2011). This species is also less sexually dimorphic than Cercocebus torquatus (Groves 2001). The skull of the male is smaller than in C. torquatus and also has a narrower, shorter face. Both sexes also have a significantly lower ascending ramus of the mandible compared to other closely related species (Groves 1978).

Male sooty mangabeys are larger, heavier, and have larger canines than in females (Fruteau, Range, and Noe 2010). The female skull is 87% the size of that of the male (Groves 1978).

The mass of the sooty mangabey ranges from 8.5 to 14 kg for males and 5 to 9 kg for females, with an average of 8.593 kg (Kingdon 1997, Rowe 1996, Mann et al. 1983). The head and body length is 40 to 60 cm in females and 47 to 67 cm in males, while tail length is 40 to 80 cm in both sexes. The height at shoulder for females is 38 to 42 cm and 40 to 45 cm in males (Kingdon 1997).

The skin of the sooty mangabey has unique histological and biochemical properties including subepidermal cholinesterase-reaction nerve fibers over the body surface, and specialized nerve end organs in many areas of the body. There are also specialized nerve end-organs at the base of the epidermal ridges of the fingertips (Machida et al. 1965).

There are two known subspecies of C. atys . The first, Cercocebus atys atys , is noted for being smoky gray, occasionally with a small dorsal stripe but never with a whorl or crown on the head, and crown hairs with a black tip and straw-colored band. The second, Cercocebus atys lunulatus (white collared (crowned) mangabeys) is noted for a whorl or crown on the head, a darker face, a more prominent dorsal stripe, and a white oval mark edged with black on the nape. The hands and feet in white collared mangabeys are more similarly colored to the body and have a white underside (Groves 2001).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Sooty mangabeys live in multi-male, multi-female groups of 15 to more than 100 individuals (Stahl and Kaumanns 2003). This social structure has led to a polygynandrous (promiscuous) breeding system, where both males and females have multiple partners (Gouzoules 1984; Fruteau, Range, and Noe 2010).

Although in a promiscuous system females are expected to be aggressive towards each other when competing for mates, no such behavior has been found in the sooty mangabey. However, females are often the victims of aggression from males, and resident males sometimes slap females when they present themselves at the beginning of the breeding season. Males are part of a linear dominance hierarchy, where the highest-ranking male attempts to copulate with all females (Range 2005). Overall, more highly ranked males mount females more often (Fruteau, Range, and Noe 2010).

Non-resident males who visit a group often attack mothers with infants, and often succeed in committing infanticide. Older and higher ranking males defend the females they mated with against such infanticide. After infanticide has been committed, the female immediately goes into estrous, giving the attacking, sneaky male an opportunity to mate with her (Fruteau, Range, and Noe 2010).

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Male sooty mangabeys become sexually active at a little less than 1 year of age, but their earliest ejaculation is at 4 years old. Young males, starting at 1 year, mount sexually mature females. Males actively mount more females from the ages of 3 to 4, during adolescence, than from ages 5 to 6, during sexual maturity (Gust and Gordon 1991). Juvenile males are even more likely to mount sexually mature females than adult males (Rowe 1996). The age of first perineal swelling for females is at 30 to 39 months, around the age of the first menses, and the first birth is usually approximately a year later at 49 to 55 months (Ehardt 1988a, Ehardt 1988b, Mann et al. 1983). The average time between births is 13 to 16 months; having a longer interbirth interval is associated with lower infant mortality rates (Gust and Gordon 1991). Sooty mangabeys give birth to a single infant at a time. Their birthrate is 0.92/yr, and their average gestation period is 167 days (Refisch and Kone 2005).

Female perineal swellings during the estrous cycle last 34.5 days and signal to males that they are capable of mating. Males are able to distinguish between a female’s maximal fertile swelling and a postconception swelling, which occurs during the postconception estrus (Rowe 1996). However, sexual swellings in captive females were not shown to accurately reflect peak fertility, but do represent overall ability to copulate (Whitten and Russell 2006). Females sexually present themselves more frequently to males than to other females, do almost all of the presenting, receive all of the mountings, and perform as many genital inspections as males (Bernstein 1976). More highly ranked males mount females more often than do lower ranked males (Fruteau, Range, and Noe 2010).

Mating first begins with the male grasping the female’s ankles while he mounts her from behind; the female then vocalizes and darts away from him before allowing him to mount her again. Females make a soft grunt during copulation (Gust and Gordon 1994). Females often manually stimulate their perineal area during copulation (Gust and Gordon 1991).

In the wild, mating begins in May, peaks in July to August, and ends in September, although births are sometimes seen throughout the year (Mann et al. 1983). Sooty mangabeys in captivity do not show strong seasonality in mating (Bernstein 1976).

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

At birth, infants are carried on their mother's ventral side but are later carried on the back after a few months. The mother of the infant gives it intensive care for the first 2 to 7 months of life, and more general attention throughout the rest of the first year (Bernstein 1976). The lactation period is 4 to 10 months (Fruteau, Range, and Noe 2010). Aunts of the infant groom the infant from ages 10 to 12 months more than the mother does; siblings, both male and female, also groom infants they are related to (Bernstein 1976). Mothers have also been observed grooming the infants’ eyelashes with a stone (Kyes 1988). Males occasionally carry young to protect the young, but not as a social buffer, since they usually carry infants that they sired themselves (Range and Noe 2002).

Females who lose their infants within six months of their birth immediately re-enter estrus, while mothers who do not lose their infants do not. Therefore, males who kill infants within these six months can reproduce with the female soon after committing infanticide (Fruteau, Range, and Noe 2010).

At birth, the infant is given a rank immediately below the mother, but male offspring quickly rise above the mother in the group ranking after a few years (Bernstein 1976).

Infant neglect and abuse, while not common, has been observed in captive sooty mangabey groups, and is more likely to impact first born young (Maestripieri, Wallen, and Carrol 1997).

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • male
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female
• maternal position in the dominance hierarchy affects status of young

Lifespan/Longevity

Average lifespan in the wild for sooty mangabeys is 18 years (Rowe 1996). Average lifespan in captivity for males is 26.8 years (Carey and Judge 2000).

Behavior

Sooty mangabeys are quadrupedal, terrestrial, diurnal monkeys who live in multi-male, multi-female groups (Rowe 1996, Range 2005). They have sexually dimorphic behavioral patterns: males engage in social behaviors more often and females engage in submission and receive agonistic behaviors more often. In captivity, they spend 70% of the day on the ground, and of that 35% of their day feeding and 5% of it drinking. Immature monkeys play more than adults do. They are always within 1 meter of another monkey, and are closer during harsher weather conditions, when huddling becomes more common (Bernstein 1976). In the wild, 74% of time is spent foraging or consuming food, and the rest of the time is spent resting and traveling (Range and Noe 2002). Although they are mostly terrestrial, they will occasionally become arboreal, especially to avoid predator attacks (Range and Fischer 2004).

Unlike many non-human primates, sooty mangabeys do not have a typical strictly matrilineal social structure (Gust and Gordon 1994). However, the behavior of wild juvenile sooty mangabeys indicates that the social structure of sooty mangabeys most closely resembles a matrilineal structure. Their social structure has also been described as a “contest competition,” where females establish matrilineal dominance based lines (Range and Noe 2002). Female ranks remain constant and resemble that of their mother upon birth, while males’ ranks initially resemble their mothers at birth but are subsequently unstable, perhaps at the same time they grow larger canines around 4 years of age. Males and females rank differently; all females are ranked below the alpha female, and all males age 5-6 are ranked higher than all females. Social rank for the sooty mangabey is not solely kin-based since brothers and sisters do not occupy similar ranks. This system may prevail since females do not commonly associate with their kin more frequently than non-kin, other than their own infants (Gust and Gordon 1994). They also show no kin-preferential behavior among adults (Ehardt 1988b). Juvenile males approach adult males more than females do, and juvenile females do not approach other females based on their rank (Range 2006). The female of the alpha matriline interacts more with males than other females, and preference is shown for grooming the oldest male (Ehardt 1988a). Captive sooty mangabeys do not exhibit a unidirectional matrilineal hierarchy, but are more affiliative and less kin-dependent (Stahl and Kaumanns 2003).

Females are philopatric, while males immigrate into other groups. Sooty mangabey males have a dispersal pattern where some males are always residents of the same group, while others leave their group for several months at a time. Solitary unknown males and resident males of near-by groups often interact with females. Females can distinguish between group and non-group member calls, possibly to help prevent infanticide attacks (Range 2005).

Sooty mangabeys have one of the lowest rates of agonistic behavior and contact aggression of any Old World monkey. Most biting behavior is harmless, consisting of a light bite on the tail or rump. Alliances and strong matrilineal support are relatively unimportant in this species, and thus a controlled form of aggression is observed. However, rank challenges by females, some even fatal, were observed in the formation of social rank in a captive group (Gust and Gordon 1991).

In captivity, higher ranked females have been observed to stay longer at feeding sites and eat higher quality foods than low ranking females. Males engaged in agonistic interaction with females when limited food was available, and thus females were submissive to males based on their own rank. Females in the wild associate with higher-ranking males in order to gain access to higher quality food patches. This association also protects females against potential predators and infanticidal males, while the male maintains access to a high quality female for mating (Stahl and Kaumanns 2003).

Sooty mangabeys have been observed using a stone for grooming infants. It is unclear whether this use represents tool use (Kyes 1988). Frugivorous monkeys, like the sooty mangabey, who require high levels of spatial memory, are expected to have high levels of intelligence, so tool use does not seem unreasonable for their level of intelligence. Sooty mangabeys can also distinguish between trees that are fruiting and not fruiting, and choose to approach fruiting trees with a higher probability. They also may have the ability to assess whether a tree is fruiting without visual cues, based on spatial memory of previous tree visits. They even remember the location of fallen fruit, and return later to retrieve it when it becomes accessible (Janmaat, Byrne, and Zuberbuhler 2006).

• Key Behaviors
• scansorial
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social
• dominance hierarchies dominance hierarchies

Home Range

Sooty mangabeys live in groups in the wild that are spaced 3 km from each other (McGraw and Bshary 2002). They can live in groups of over 100 individuals with home ranges of 6-8 km2 (700-800 ha), which often overlap with other groups (McGraw, Vick, and Daegling 2011; Janmaat, Byrne, and Zuberbuhler 2006).

Communication and Perception

The most common call of sooty mangabeys is a soft grunt, also known as a staccato bark, which consists of a multitude of rapid grunts and a whoop that is finished by a multi-syllabled rumble (Kingdon 1997). Sooty mangabey vocalizations can be grouped into several main categories. Grunts, low frequency vocalizations, are the most common vocalization, and are more commonly produced by males and in foraging activities. Twitters, ranging from soft, melodic sounds to harsher sounds, are only heard from adult females and juveniles of both sexes in foraging and social interactions. They can consist of up to 23 syllables. Twitters can be heard when a female approaches another group member, and are common when foraging in widely dispersed areas to locate another foraging group. Screams, which are loud, noisy agonistic vocalizations, are mostly heard from juvenile and adult females during contact aggression. Growls are multi-syllabic, also occur in agonistic situations, and are often accompanied by a raised eyebrow. Grumbles, hoos, intense threats, and waus are other calls heard during agonistic interactions. Copulation calls have a complex phrase structure and last up to 10 seconds. They can be heard from females during copulation and occasionally during defecation, as well as from males after ejaculation. Whoop gobbles are long calls, only used by adult males, and are associated with contacting other groups. Alarm calls are produced by both males and females, and have been heard in response to Gaboon vipers, leopards, and African crowned eagles. There appears to be a different alarm call specific to each predator (Range and Fischer 2004).

Sooty mangabeys exhibit many variable facial expressions, most of unknown meaning (Kingdon 1997). A lipgrin with a protrusion of the tongue is often seen but its significance is unknown (Bernstein 1976). Frequent eyelid raising indicates a threat (Gust and Gordon 1994).

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Sooty mangabeys are hard object feeders with a narrow diet primarily consisting of fruits and nuts, especially palm nuts, with specialization on their flesh and kernels. They are also known to eat stems, roots, shoots, and leaves of swamp plants, as well as grass, seeds and fungi (Kingdon 1997, Macdonald 2001). Invertebrates are another staple of their diet (McGraw, Vick, and Daegling 2011). They have extremely strong, powerful jaws and massive incisors that allow them to consume a hard object diet. Powerful post-canine biting allows them to crack and consume hard nuts that other animals cannot eat (Rowe 1996, Estes 1991). A complex premolar profile and their thicker enamel also reflect their hard object feeding lifestyle (Daegling et al. 2011).

The most common food in their diet and hardest item they feed on is nuts from Sacoglottis gabonensis , which can comprise 25 to 80% of the whole diet seasonally and which they crush using their large premolars. These nuts are mostly recovered from leaf litter on the forest floor and are covered with an extremely hard casing (McGraw, Vick, and Daegling 2011). When consuming these nuts, they exhibit a powerful isometric bite with incisal preparation and powerful post-canine crushing (McGraw, Vick, and Daegling 2011). The fruit of Anthonota fragrans was observed to seasonally form up to 25% of the diet (Janmaat, Byrne, and Zuberbuhler 2006).

Male and female sooty mangabeys have different dietary patterns. Males tend to eat more hard nuts, seeds, and invertebrates, while females typically consume softer seeds and fruits. Males tend to use more incisions and post-canine crushing. Adults and non-adults also differ in feeding patterns, with adults eating more fungi and soft seeds, and non-adults eating more S. gabonensis seeds (McGraw, Vick, and Daegling 2011).

• Primary Diet
• herbivore herbivore
  • granivore granivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• terrestrial worms

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts
• fruit

• Other Foods
• fungus

Predation

Sooty mangabey predators include crowned hawk eagles, leopards, humans, and chimpanzees. Sooty mangabeys are noted for their sentinel ability to spot predators on the ground (McGraw and Bshary 2002). Gaboon vipers also elicit alarm calls, although a death from one has yet to be observed in the wild (Range and Fischer 2004). In response to perched African crowned hawk eagles, sooty mangabeys produce an alarm call, and if one is observed flying, the sooty mangabeys descend trees onto the ground. When leopards are observed, sooty mangabeys ascend trees and vocalize alarm calls (Range and Fischer 2004).

Ecosystem Roles

Sooty mangabeys follow arboreal monkeys to feed on their dropped fruit. They also act as seed dispersers since their diet includes seeds (Rowe 1996).

Sooty mangabeys have been observed in the wild as participants in mixed primate species groups in the Tai National Park along with western red colobuses ( Piliocolobus badius ) and Diana monkeys ( Cercopithecus diana ). These inter-species groups ensure better protection against predators, and usually involve monkeys with different dietary needs to eliminate food competition (Macdonald 2001). These inter-species groups allow arboreal monkeys to come closer to the ground and extend their niche when sooty mangabeys are nearby, due to a perceived reduced threat of terrestrial predators. The sooty mangabey acts as a sentinel for ground predators, and its alarm call helps warn the less observant arboreal species of predators (McGraw and Bshary 2002).

A necroposy of a juvenile female sooty mangabey indicated the presence of lung worms of the Metastrongylidae family, the larval form of Porocephalus armillatus , the pancreatic fluke Brodenia serrata , and Hepatocystis kochi (Hysell et al. 1970). Abbreviata poicilometra , a physalopterid, can also infect this species (Slaughter and Bostrom 1969).

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Sooty mangabeys provide a good study primate for evolutionarily, behaviorally, ecologically, and medically related studies. They are studied in the wild at Tai National Park in southwestern Ivory Coast, and in a captive colony at the Yerkes Regional Primate Research Center at Emory University (Fruteau, Range, and Noe 2010; Gust and Gordon 1992). Anthropological research has allowed inferences on human behavior, such as hard object feeding, due to their relatively close phylogenetic relationship to humans (Daegling et al. 2011). This species is also an incredibly important medical study animal as it is a natural host of simian immunodeficiency virus 2 (SIV-2), giving researchers insights on HIV-2 in humans. Sooty mangabeys can also contract and spread leprosy (Hamilton et al. 2008; Riddick et al. 2010).

Sooty mangabeys are hunted for their meat (Refisch and Kone 2005).

• Positive Impacts
• food food
• research and education

Economic Importance for Humans: Negative

Sooty mangabeys are seen as agricultural pests since they frequently ravage farms, mostly rice paddies, where they can cause extensive economic damage (Kingdon 1997). Attempts to conserve this species may hurt industrialization in the region, since the habitat of this species is composed of trees useful for timber and firewood (Galat and Galat-luong 2006; Oates, Gippoliti, and Groves 2011).

Eastern sooty mangabeys, which are often infected with SIV-2, may have initially been the vectors for SIV-2 to evolve into HIV-2 in humans (Santiago et al. 2005).

• Negative Impacts
• injures humans
  • carries human disease
• crop pest

Conservation Status

While hunting sooty mangabeys is difficult because they live in dense, swampy forests, they are easily trapped since they spend the vast majority of their time foraging on the forest ground (Kingdon 1997). Sooty mangabeys are currently being hunted at two times a sustainable rate in the Tai forest region in Ivory Coast for their meat, which is decimating their population (Refisch and Kone 2005). Human activities and land use also threaten the sooty mangabey, as urbanization has caused deforestation in their natural habitat (Galat and Galat-luong 2006). Large-scale logging has greatly reduced the range of this species (Nowak 1991). For this reason, C. atys is listed as vulnerable according to the IUCN and is in Appendix II of the CITES database (Oates, Gippoliti, and Groves 2011; UNEP-WCMC 2012).

Sooty mangabeys, Cercocebus atys atys , are near threatened, as their population has declined 20 to 25% over the past few decades (Oates, Gippoliti, and Groves 2011). This subspecies is present in two protected areas, Tai National Park and Sapo National Park (Oates, Gippoliti, and Groves 2011).

White-naped mangabeys, Cercocebus atys lunulatus , are endangered, and was one of the 25 most threatened primate species (Galat and Galat-Luong 2006). The population has declined by at least 50% over the past 27 years, largely attributed to habitat destruction and hunting pressure, mostly in Ghana (Oates, Gippoliti, and Groves 2011). The recent addition of the AGEREF/Comoe-Leraba Reserve to the Comoe National park could substantially increase the likelihood of this subspecies’ survival (Galat and Galat-Luong 2006). This park, however, is currently threatened by civil conflict and hunting (Oates, Gippoliti, and Groves 2011). The West African Primate Conservation Action (WAPCA) has highlighted white-naped mangabeys as one of two primate species to save in West Africa and hopes to employ hunters of the monkeys as game wardens to ensure its preservation (Dale 2001).

Captive breeding programs in European zoos also hope to increase population numbers (Oates, Gippoliti, and Groves 2011).

The US Fish & Wildlife Service (USFWS) restrictions currently make continued research on captive sooty mangabeys and SIV challenging. The Yerkes facility is working with collaborators from other institutions to ensure the protection of wild sooty mangabeys, while using colony bred animals to learn more about the basic biology of this species. These institutions hope that their efforts will encourage the USFWS to ease restrictions on the research of the captive colony and SIV (Else et al. 2006).

Other Comments

Sooty mangabeys are natural hosts of SIV-2, meaning they acquire the infection but never show any symptoms for it. The captive colony of sooty mangabeys at the Yerkes facility are all infected with SIV-2 and have provided an important study opportunity for HIV researchers. SIV-2 is non-pathogenic in sooty mangabeys (Riddick et al. 2010). One possible route of exposure between these monkeys is through grooming, where blood sucking parasites are removed using the mouth (Santiago et al. 2005). The human genome sequencing center at the Baylor College of Medicine is currently sequencing the genome of sooty mangabeys to understand their “AIDS resistance” factors ("Sooty Mangabey" 2011).

Sooty mangabeys are the only primates other than humans known to acquire leprosy from their own species (Rowe 1996). Leprosy in wild sooty mangabeys, and subsequently in the captive Yerkes sooty mangabey colony, eventually led researchers to discover that Rhesus monkeys infected with SIV were more susceptible to also being infected with leprosy; conversely this led to the discovery that leprosy may prevent AIDS induced mortality (Hamilton et al. 2008).

Sooty mangabeys are often considered a subspecies of Cercocebus torquatus as Cercocebus torquatus atys (Nowak 1991). Cercocebus lunulatus has been proposed as a separate species rather than its current status as a subspecies of Cercocebus atys (Smith 2012).

Additional Links

Encyclopedia of Life

Contributors

Scarlett Lee (author), Yale University, Eric Sargis (editor), Yale University, Rachel Racicot (editor), Yale University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

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