Passive sampling effects and landscape location alter associations between species traits and response to fragmentation

Abstract

As tropical reserves become smaller and more isolated, the ability of species to utilize fragmented landscapes will be a key determinant of species survival. Although several ecological and life history traits commonly are associated with vulnerability to fragmentation, the combination of traits that are most highly influential and the effectiveness of those traits in predicting vulnerability across distinct landscapes, remains poorly understood. We studied use of forest fragments by 25 mid- and large-sized neotropical mammals in Guatemala to determine how seven species traits influence vulnerability to fragmentation. We measured vulnerability in two ways: one measure that did not remove passive sampling effects (proportion of fragments occupied), and one that did (difference in occupancy rates within continuous and fragmented sites). We also examined the influence of species traits on patch occupancy rates of the same set of mammals on two landscapes in Mexico. When not accounting for passive sampling effects, body size, home range size, and vulnerability to hunting influenced how species responded to fragmentation. However, after controlling for passive sampling effects, only vulnerability to hunting strongly influenced sensitivity to fragmentation. Species that were heavily hunted were much less common in forest patches than in continuous forest sites of the same sampling size. The cross-landscape comparison revealed both similarities and differences in the species traits that influenced patch occupancy patterns on each landscape. Given the ubiquity of hunting in tropical environments, our findings indicate that management efforts in fragmented landscapes that do not account for hunting pressure may be ineffective in conserving heavily hunted tropical species. Our study also indicates that species traits may be useful in predicting relative patch occupancy rates and/or vulnerability to fragmentation across distinct landscapes, but that caution must be used as certain traits can become more or less influential on different landscapes, even when considering the same set of species.