The nutritional ecology of the Zanzibar red colobus (Piliocolobus kirkii) within modified habitats

Abstract

As primate habitats are being continually altered by human activity, animals need to adapt in various ways in order to survive. This is particularly true for folivorous primates as modified landscapes usually results in directly affecting their food resources. With disturbed habitats comes an increased number of introduced plant species. These exotic plants most often contain unfamiliar secondary compounds that can be potentially harmful when ingested. There is currently little work that investigates how living in a modified environment impacts the dietary ecology of folivores, which is vital when implementing conservation strategies to ensure their survival. This study focuses on four groups of endangered Zanzibar red colobus monkeys (Piliocolobus kirkii) that live in a variety of anthropogenically modified habitats in the Jozani Chwaka-Bay National Park & Biosphere Reserve, Zanzibar. One group resided in the southern part of the National Park, utilising heavily disturbed regenerated edge forest and the surround shambas (farmlands). Three other groups deeper in the forest were also followed, whose habitat disturbance levels ranged from low to moderate. Within these environments, some groups have adopted the unusual behaviour of consuming charcoal, which is thought to serve as a detoxification agent by adsorbing harmful phenolic compounds found in many of these introduced plant species. By comparing data on different habitats, behaviours, diets and the chemical constituents of food plants, a better understanding of how these folivores have adapted to cope with modified environments, will be gained. Results indicate that habitats, behaviours, diets and feeding strategies have changed since research was conducted in the area by Mturi (1991) and Siex (2003). Overall, the shamba group had a larger home range, a broader dietary diversity containing more exotic plant species and consumed charcoal most frequently, compared to the forest groups. Nutritional analysis of samples from each groups diet, indicated that the ZRC food items differed greatly in levels of important constituents; with the overall nutritional profile of samples from one group being higher in protein, while that of the other groups excelled in energy, minerals or was relatively balanced. Habitat disturbance levels did not coincide with the nutritional fingerprints of the samples analysed. This study elucidates how the ZRC are using their habitats when exposed to modified habitats along with how better conservation strategies can be implemented to benefit this endemic species.