Spatial Factors and Stochasticity in the Evaluation of Sustainable Hunting of Tapirs

Sustainable hunting, the extraction of game without reducing its density, is a desirable approach to the use of wildlife. Assessment of sustainable extraction in many parts of the world is difficult; it has recently been done by a method proposed by Robinson and Redford (1991): a maximum number of animals that can be extracted per unit area is calculated based on life-history parameters and density estimates. If extraction is higher than that maximum number, it is deemed unsustainable. We extended the method by adding spatial and stochastic components through an individual-based model of a population of female tapirs (  Tapirus sp.) and conducted a sensitivity analysis to evaluate the importance of spatial and life-history parameters. Our analysis suggests that spatial factors, such as the shape of the hunted area and the size of the surrounding population, may be important in determining the sustainability of extraction. For long-lived, slow-reproducing mammals such as tapirs, survival to age of last reproduction is the most critical parameter, but the shape of the hunting zone and population density can be critical, especially in unsustainable hunting scenarios. We advocate long-term studies of tapirs to collect information on spatial movements and survival rates that could then be used for development of proper management plans.