Status of Zanzibar Red Colobus and Sykes's Monkeys in Two Coastal Forests in 2005

Abstract

We censused two discrete subpopulations of the endangered Zanzibar red colobus (Procolobus kirkii) and sympatric Sykes's monkeys (Cercopithecus mitis albogularis) between February 2004 and September 2005 in two coastal forests in Zan- zibar, including the northernmost (Kiwengwa-Pongwe Forest) and some of the southernmost (Uzi and Vundwe Islands) extents of P. kirkii's range. Surveys totalled 365 hours and 307.8 km along >16 km of line transects; 472 sightings were made (Red colobus n = 252; Sykes's monkey n = 220). The southern forests (coral rag with adjacent mangrove) of Uzi and Vundwe Islands were found to support P. kirkii at a higher estimated density (29.6 groups/km²) relative to the northern coral rag forest (lacking mangrove) in Kiwengwa-Pongwe (7.5 groups/km²). However, for red colobus in coral rag, up to c.40% of these groups could EH�≥VXEJURXSV¥�EDVHGRQRXUREVHUYDWLRQVRIFRQVLVWHQW�oVVLRQ�