Piliocolobus kirku (Gray, 1868)

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 : 706-707

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Zanzibar Red Colobus

Piliocolobus kirku

French: Colobe de Zanzibar / German: Sansibar-Stummelaffe / Spanish: Colobo rojo de Zanzibar

Other common names: Kirk's Red Colobus

Taxonomy. Colobus kirkii Gray, 1868 ,

Tanzania, Zanzibar.

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. P. kirkii is the easternmost representative of the genus. Monotypic.

Distribution. Zanzibar I (mainly in the SE) and Muyuni and Uzi Is, off E Tanzania. Introduced on nearby Pemba I.

Descriptive notes. Head-body 45-50 cm, tail 42-55 cm; weight 7-9 kg. It is possible that female Zanzibar Red Colobus are larger than males. It is the smallest and most distinctive species of Piliocolobus . Hindlimbs are elongated. It is an essentially tricolored form; arms, shoulders, and forepart of the back are black, with the remainder of the back, crown, and base of the tail brick-red. Shaggy hair surrounds the face like a halo. Underside (including inner surfaces of forelimbs and all of hindlimbs) and terminal part of the tail are creamy-white. Hands and feet are black and fringed with white hairs. Face is black with a pink zone around the mouth and lower part of the nose; this pattern occurs in juveniles of many other red colobus, but it is retained for life only in Zanzibar Red Colobus . Eyes are ruby-red. Skull has a short facial skeleton but a long palate. A mtDNA places the Zanzibar Red Colobus in a distinct East African clade with the Udzungwa Red Colobus ( P. gordonorum ), with which it shares very similar vocalizations.

Habitat. Secondary forest patches, swamp forest, mangrove, fallow bush, and agricultural land, from sea level to 110 m. The Zanzibar Red Colobus is found primarily in areas of groundwater forest and scrub forest on coral rag on the southern and eastern side of the island. It originally inhabited tropical evergreen forest (now largely destroyed). It prefers the forest canopy.

Food and Feeding. Young leaves and leaf buds account for more than 50% of the diet of the Zanzibar Red Colobus . In forest-dwelling groups, unripe fruit accounts for an additional 25% of the diet, whereas in groups living in agricultural areas, leaves from herbaceous species are the second-most consumed item (c.15% of the annual diet). Some groups frequently feed on mangrove leaves, and groups living on coral rag appear to subsist on a drier, coarser diet than any recorded for red colobus monkeys. Individual Zanzibar Red Colobus occasionally eat soil or insect clay, and also charcoal from a burned stump.

Breeding. Female Zanzibar Red Colobus display a substantial pink sexual swelling during the periovulatory period. Births take place throughout the year, and a single young is born after a gestation of ¢.5 months. The interbirth interval is 26-55 months. The neonatal coat is white (not blackish as in other red colobus).

Activity patterns. The Zanzibar Red Colobus is diurnal and arboreal. Studying groups at two differentsites, K. Siex found they spent 44-47% of their time resting, 29% feeding, 6-12% traveling, 7-15% engaging social activities, and 7-15% in other activities.

Movements, Home range and Social organization. Daily movements average 310-565 m, and home ranges are 13-25 ha (home ranges overlap). The Zanzibar Red Colobus lives in multimale-multifemale groups, averaging 30 individuals.

Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List (as Procolobus kirkii ). The Zanzibar Red Colobusis listed as Class A in the African Convention on the Conservation of Nature and Natural Resources. It is nominally protected in Tanzania under the Forest Resource Management and Conservation Act of 1996. These beautiful monkeys are threatened by hunting and land clearance. Two specimens of the Zanzibar Red Colobus obtained in the mid-19" century reportedly came from the Pangani River, on mainland Tanzania, but it is certainly extirpated there now. Vast tracts of Zanzibar’s native forest have been destroyed for timber, charcoal production, cultivation, and bush-burning. Local people tolerate the Zanzibar Red Colobus and seem to appreciate its importance as a tourist attraction; however, it is occasionally shot for food or sport, or as a crop pest. On Zanzibar, it is found mainly in the south-eastern part of the island in Jozani-Chwaka Bay National Park, adjacent agricultural areas to the south, and the coral thickets and mangrove swamps of Uzi Island, 10 km to the south-west. It is also found at low densities in isolated populations in coral thickets along Zanzibar’s eastern coast from Kiwengwa in the north to Mnyambiji in the south. On the western coast, there is a small isolated group in mangrove swamps of Maji Mekundu. While the Zanzibar Red Colobus has adapted well to human encroachment, its extent of occurrence is less than 5000 km* and probably less than 760 km?, and there is severe fragmentation and continuing declines in area of occupancy, habitat, and numbers of mature individuals. Less than 50% of the population is legally protected and reasonably secure in the small Jozani Chwaka Bay National Park (c.60 km®). There are occasional deaths due to road kills south of the park, but the installation of speed bumps at Jozani has reduced these incidences. The highest densities occur in ¢.40 ha of agricultural land adjacent to the southern border ofJozani Chwaka Bay National Park (784 ind/km? in 1999), but they are due to population compression following the destruction of adjacent habitat rather than intrinsic growth of the population. The density in coral thickets adjacent to Jozani Forest is probably less than 50 ind/km? The Jozani subpopulation was thought to contain ¢.500 individuals, and in 2008, the total population was estimated at less than 2000 individuals. A small translocated population (c.56 individuals) also occurs in the Masingini Forest Reserve. Creation of a new protected area at Kiwengwa, for the protection of remaining patches of coral thicket in the south and corridors between remaining habitat patches, is urgently needed for survival of the Zanzibar Red Colobus . About 14 individuals were introduced to Ngezi Forest Reserve, Pemba Island, around 1974, and a small population persists there today.

Bibliography. Camperio Ciani et al. (2001), Cooney & Struhsaker (1997), Gijzen et al. (1966), Groves (2001, 2007b), Grubb et al. (2003), Rodgers (1981), Siex (2003), Siex & Struhsaker (1999), Silkiluwasha (1981), Struhsaker (2005), Struhsaker & Leland (1980), Struhsaker & Siex (1996, 1998a, 1998b), Struhsaker et al. (1997).

Figures

Distribution. Zanzibar I (mainly in the SE) and Muyuni and Uzi Is, off E Tanzania. Introduced on nearby Pemba I.