Bushmeat hunting and management: implications of duiker ecology and interspecific competition

Duikers Cephalophus spp. are an important source of food and income throughout the forest regions of Central and West Africa, and current levels of hunting are probably unsustainable, at least near large settlements. The direct effects of hunting consist of two main aspects: overexploitation of target species, and incidental hunting of non-targeted or rare species because hunting is largely non-selective. There are many methodological and practical problems to a technical approach to overexploitation, and there are increasing calls for alternative measures such as zoning and enforcement of exclusive local resource rights. There is also increasing recognition of the need to ensure that hunting is more selective. This paper reviews current knowledge of duiker ecology and niche separation in order to assess likely indirect effects of these measures on different species. The main factor separating fundamental niches of sympatric species is body size, which limits dietary choice. Additional descriptive factors include anatomical features - particularly the jaw musculature and size of mouth and neck; activity patterns and habitat preferences within closed canopy forest. However, there is wide overlap of diets and broad tolerance of habitat disturbance by most species, and therefore niche overlap and interspecific competition may be high. In the Upper Guinean forest in West Africa, but not in Central Africa, differential use of closed canopy forest and secondary vegetation also appears to be an important factor in niche separation; three pairs of species seem to be separated primarily by this factor. Distributional variations in habitat use suggest that at least in the case of the yellow-backed duiker and the endangered Jentink's duiker, the separation is due to competition rather than to fundamental niche constraints. Selective hunting or zoning will thus have indirect effects on non-targeted species through changes in competitive dominance in different habitats.