Occupancy and abundance of a West African mangabey species (Cercocebus atys Audebert, 1797) in forest patch habitat

Sooty mangabeys are Old World primates from the Upper Guinea Rainforests of West Africa. They suffer from habitat degradation due to deforestation and hunting for the bush-meat trade. Tiwai Island and adjacent small islands are a small protected area surrounded by the Moa River that is known for its high diversity of primate species. We evaluated the occupancy and abundance of sooty mangabeys on Tiwai Island and the surrounding islands using camera traps during 2008-2011. Over two seasons, we obtained a naive occupancy rate of 0.77 for Tiwai Island but only 0.19 for surrounding smaller islands. We used Abundance-Induced Heterogeneity Model and Royle Repeated Count Model to estimate the abundance of 326 +/- 92 (SE) and 530 +/- 102 (SE) individuals of sooty mangabeys respectively. Based on these occurrences, sooty mangabeys usually appeared in riparian, mature and young secondary forests. Activity patterns of sooty mangabeys based on circadian patterns of detections confirmed that they were diurnal with several activity peaks during the daylight hours. The results of this study suggest that a viable population of sooty mangabeys still inhabits Tiwai Island and its vicinity, but that their core population is primarily limited to the Tiwai Island reserve. Thus, there is a need to protect the island and its adjacent habitats to ensure the conservation of sooty mangabeys in particular and other primate species in general.