Piliocolobus rufomitratus (Peters, 1879)

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 550-755 : 709

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Tana River Red Colobus

Piliocolobus rufomitratus

French: Colobe de la Tana / German: Tana-Stummelaffe / Spanish: Colobo rojo del Tana

Other common names: Eastern Red Colobus

Taxonomy. Colobus rufomitratus Peters, 1879 ,

Kenya, Tana River, Muniuni. (2° 6’ 24” S, 40° 6’ E).

Modern taxonomic arrangements of the colobus monkeys either divide the red colobus and the Olive Colobus into two genera, Piliocolobus and Procolobus , respectively, or consider them to belong to one genus, Procolobus , with two subgenera ( Procolobus for the Olive Colobus and Piliocolobus for the red colobus). We follow here C. P. Groves in his publications of 2001 and 2007 in using two genera. Monotypic.

Distribution. SE coastal Kenya, confined to a narrow stretch of forest along the lower Tana River, mainly from Garsen N nearly as far as Wenje; recently also found in the forests of the Tana River Delta.

Descriptive notes. Head-body ¢.50 cm,tail ¢.65 cm; weight ¢.9 kg. The Tana River Red Colobusis a very small species, nearly as small as the Zanzibar Red Colobus ( P. kirkii ). Males are larger than females, with a somewhat shorter tail. Skull is distinct, and strongly different from all other species of red colobus. It is very broad across orbits but narrow across canines, and teeth are notably large. Pelage is dark gray, with a slight buffy tinge above and a grayish-white underside. Limbs are lighter in color than the body, and tail darker, becoming nearly black toward the tip. Hands and feet are a little, if at all, darker than the rest of the limbs. Crown is brick-red and surrounded by a dark gray rim, with a whorl behind each ear leading to a low transverse crown crest. There is a whorl on either side of the crown above the ears, and the forehead and hairs over the ears are rimmed with black. Adult females have a large, prominent clitoris. DNA analysis places the Tana River Red Colobus close to other East African species, including the Ashy Red Colobus ( P. tephrosceles ), Lang’s Red Colobus ( P. langi ), and Foa’s Red Colobus (P. foa).

Habitat. Relict evergreen gallery forest patches and narrow riparian forest strips, bordering rivers, streams, lakes, and wetlands in a landscape that otherwise has few trees.

Food and Feeding. The Tana River Red Colobus eats mainly young leaves, although flowers and fruit can make up a significant part ofits diet.

Breeding. There is no information available for this species.

Activity patterns. The Tana River Red Colobus is diurnal and arboreal. Studies have shown that it tends to spend 48-55% ofits day resting, 23-30% feeding, 7-24% moving, and 2-7% engaging in social activities.

Movements, Home range and Social organization. Average daily movements of Tana River Red Colobus are 461-603 m, with home ranges of 9-13 ha. Group sizes are 4-24 individuals, with 1-2 adult males in each group. Dispersal is much more common in females than males. Reported densities are 33-253 ind/km?.

Status and Conservation. CITES Appendix I. Classified as Least Concern on The IUCN Red List (as Procolobus rufomitratus ). The Tana River Red Colobus is listed as Class B in the African Convention on the Conservation of Nature and Natural Resources. It is threatened by changes in vegetation due to dam construction, irrigation projects, and water diversion that have altered the water table; forest clearing for agriculture; fires eroding levee forests; degradation due to livestock and firewood collection; selective felling of fig trees ( Ficus , Moraceae ) for canoes; and hunting. The area inhabited (25 km?) is broken into more than 70 patches, but two-thirds of the population occurs in the continuous forest belt along either side of the Tana River between Munazini and Makere ya Gwano, near the northern end of its distribution. The total population is estimated at 1100-1300 individuals, down from an estimated 1200-1800 in 1975. This is not considered a significant decrease and suggests that the Tana River Red Colobus may have developed strategies to cope with its shrinking habitat. Recent surveys indicate that at least 86 groups occur in 34 forest patches; mean group size has declined by c.50% since the 1970s. It is now protected somewhat within the confines of the Tana River National Primate Reserve. Regardless, it has a very small extent of occurrence (52 km?), which is gradually becoming smaller and more fragmented. The Tana River Red Colobus occurs at less than five locations, and there is continuing decline due to the current rapid destruction of habitat. About 40% of the remaining population is in 13 km? offorest in the 169km* Tana River National Primate Reserve. Stringent habitat protection is required, and there is a need to reestablish the Mchelo Research Station. The proposed Tana Integrated Sugar Project in Tana River and Lamu districts threatens more than 200 km? of semi-natural habitat in the area. Tana River Red Colobus requires regular monitoring because it could very quickly become critically endangered.

Bibliography. Decker (1994b), Decker & Kinnaird (1992), Butynski & Mwangi (1995), Groves (2001, 2007b), Groves et al. (1974), Grubb et al. (2003), Marsh (1978, 1979a, 1979b, 1981a, 1981b, 1981c), Mbora (2000, 2003), Mbora & Meikle (2004a, 2004b), Mowry et al. (1996), Ting (2008).

Figures

Distribution. SE coastal Kenya, confined to a narrow stretch of forest along the lower Tana River, mainly from Garsen N nearly as far as Wenje; recently also found in the forests of the Tana River Delta.