Cercocebus sanjer Mittermeier 1986
Creators: name: Russell A. Mittermeier
name: Anthony B. Rylands
name: Don E. Wilson
Publisher: name: Lynx Edicions
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Primates
Cercopithecidae
Cercocebus
Cercocebus sanjer

description: 26.
Sanje River Mangabey
Cercocebus sanjer
French: Mangabey de la Sanje / German: Sanje-Mangabe / Spanish: Mangabey del Sanje
Other common names: Sanje Crested Mangabey, Sanje Mangabey
Taxonomy. Cercocebus sanjei Mittermeier, 1986,
Tanzania, Sanje Waterfall, Mwanihana Forest.
Some experts have regarded C. sanjei as a subspecies of C. galeritus. Monotypic.
Distribution. S Tanzania, confined to Mwanihana Forest and the E slopes of the Udzungwa Mts.
Descriptive notes. There are no specific measurements available. In his 1997 Field Guide to African Mammals, J. Kingdon provided the following estimates: head-body c.b0-65 cm, tail ¢.55-65 cm. Body masses of male and female Sanje River Mangabeys are c.10-3 kg and c.5-8 kg, respectively. Crown, back, limbs and tail are speckledgray. Hands and feet are darker, and tail has a whitish tuft; belly and chest are pale orange. Face is pale grayish, with pink around the eyes and on the nose, and eyelids are off-white. Crown hairs part along midline or form a slight whorl; hairs extending back and to the sides are longer, with shorter hairs protruding outward along the brow. Body skin is bluish-white. Skin on hands,feet, and earsis dark grayish. Paracallosal skin is bluish gray, with narrow pink callosities. Sanje River Mangabeys are clearly sexually dimorphic; adult males are larger than adult females.
Habitat. Montane and submontane forest fragments, preferring riparian forest and scrub at elevations of 400-1600 m. The Sanje River Mangabey is often found in the lower understory and spends more than 50% ofits time foraging on the forest floor. It frequently moves through and uses disturbed areas and mosaic habitat. Most of the information on ecology, behavior, and reproduction of the Sanje River Mangabey comes from a habituated group in the Mwanihana Forest studied by K. Mwamende.
Food and Feeding. The Sanje River Mangabey has a variable diet, feeding on plant material (mainly fruits and seeds), insects, millipedes, and small animal prey, including slugs, snails, chameleons, frogs, and freshwater crabs. About 50% of the diet is made up offruit, 27% seeds, 11% insects and other invertebrates, 4% leaves, 2% flowers, and 2% bark and gums. They also occasionally eat more than 20 species of fungi, buds, lichens, and roots (4%).
Breeding. Sanje River Mangabeys mate throughoutthe year. Females develop prominent perineal swellings during receptive periods. Mean menstrual cycle length is 32 days, and the gestation period averages 173 days. Females give birth to a single young. As in other mangabey species, female Sanje River Mangabeys exhibit post-conception swellings, on average, 67 days after conception.
Activity patterns. Sanje River Mangabeys are diurnal and semi-terrestrial. They sleep in clumps oftall trees. One study group regularly used eight different sites scattered through its home range.
Movements, Home range and Social organization. Group sizes of Sanje River Mangabeys are c.15 to more than 40 individuals, and they are multimale-multifemale. Males disperse, and femalesare philopatric. An habituated study group in Mwanihana Forest Reserve had at least 63 individuals, including ten adult males, 21 adult females, and three subadults. Mean daily movement ofthis group was 1760 m, and its home range was ¢.240 ha. Home range and movement patterns differed significantly between seasons. During the dry season, the group moved larger distances between forest patches and traveled significantly faster than during the wet season. Groups of Sanje River Mangabeys sometimes split temporarily to travel and forage separately (fission-fusion). Estimates of 0-3-0-6 groups/km?, with a mean of 10-2 ind/group, have suggested 900 mangabeys in the 177km? Mwanihana Forest. Males display loud vocalizations known as the “whoop-gobble” calls.
Status and Conservation. CITES Appendix II. Classified as Endangered on The [UCN Red List. The Sanje River Mangabeyis listed as Class B in the African Convention on the Conservation of Nature and Natural Resources. It is estimated that fewer than 1300 individuals remain in two main populations, some 85 km apart (one consists of five distinct subpopulations). Sanje River Mangabeys are occasionally caught in snares set by local hunters. Across its distribution, the Sanje River Mangabey is threatened by habitat loss and degradation because of agriculture, infrastructure development, fires, wood extraction, and hunting. They occur in three protected areas: Mwanihana Forest Reserve, Udzungwa Mountains National Park, and Udzungwa Scarp Forest Reserve in Tanzania. Efforts to expand the boundaries of Udzungwa Mountains National Park to improve the level of protection in the current Udzwunga Scarp Forest Reserve have been unsuccessful. Demographic surveys are needed. There is a need to enforce laws prohibiting hunting in forest reserves and increase prevention of habitat alteration.
Bibliography. Ehardt (1999/2000), Ehardt & Butynski (2006, 2013), Ehardt et al. (2005), Groves (1996, 2001, 2005b), Grubb (2006), Grubb et al. (2003), Homewood & Rodgers (1981), Jolly, C.J. (2007), Jones et al. (2006), Kingdon (1997), Marshall et al. (2005), McGraw & Fleagle (2006), Mwamende (2009), Rovero, Marshall et al. (2009), Rovero, Struhsaker et al. (2006), Swedell (2011), Wasser (1985, 1993).
description: Published as part of Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, pp. 550-755 in Handbook of the Mammals of the World – Volume 3 Primates, Barcelona :Lynx Edicions on page 652, DOI: 10.5281/zenodo.6867065