Having your wildlife and eating it too: an analysis of hunting sustainability across tropical ecosystems

Unsustainable hunting of wildlife or bushmeat for human consumption across the tropics threatens both wildlife populations and the livelihoods of people who depend on these resources. The probability that hunting can be sustainable depends in part on ecological conditions that affect the 'supply' of and 'demand' for wildlife resources. In this study, supply is estimated across a number of tropical ecosystem types by calculating the theoretical 'maximum sustainable offtake' in kg/km(2) for harvestable wildlife. Demand is estimated from observed harvests in kg/km(2). We examine how supply and demand vary across relatively undisturbed ecosystems, indexed by annual rainfall. Supply is potentially highest in dry forests and wetter savannah grasslands and decreases in moist forests and more xeric grasslands. Demand tends to exceed supply in moist forests and xeric grasslands. Analogous to this ecological variation along the rainfall gradient is the gradient created by the conversion of tropical forests by humans. We hypothesise that the wild meat supply is greater in secondary forests and forest-farm-fallow mosaics than in undisturbed forests and test this with available data. We conclude that the probability that hunting will be sustainable varies with ecosystem type and degree of human disturbance and should influence where land is zoned for protected areas and where for wildlife harvests.