Effects of hunting and fragmentation on terrestrial mammals in the Chiquitano forests of Bolivia.

In recently fragmented landscapes, hunting pressure increases because hunters can access previously remote habitats. Yet fewer than 0.5% of fragmentation studies with mammals have also assessed the impacts of hunting. Herein, by means of camera-traps and track-plots, we analyzed the impact of hunting and forest fragmentation on species richness and relative abundances of twelve species of large and medium-sized mammals. With both methods we found fewer species in hunted sites than in control sites, but the effect was inconsistent in fragmented habitats with hunting. Hunting negatively affected the indices of abundance for five of the 12 species and never had a positive effect. Contrary to the hypothesis that the combination of fragmentation and hunting would lead to the largest decrease in abundance, we found that the addition of fragmentation in hunted landscapes negatively affected only two species (red bracket deer [Mazama americana] and margay cat [Leopardus wiedii]) and positively affected three smaller species (crab-eating foxes [Cerdocyon thous], coatis [Nasua nasua], and agoutis [Dasyprocta spp.]). We also found a significant relationship between body mass and the effects of fragmentation (smaller species positively affected), but no relationship between body mass and the effect of hunting. Had we only compared results from the control with fragmented sites, we would have found a negative effect of fragmentation on five species abundance indices, a negative effect on species richness, and a positive effect on three species abundance indices. These results indicate that a failure to explicitly incorporate the effects of hunting into the design of fragmentation experiments can lead to widely different conclusions.