Differential responses of large mammals to logging and edge effects

Selective logging is one of the most widespread disturbances to tropical forests worldwide, yet its impacts on large mammals remain poorly understood. We used camera trapping and hierarchical models to compare local abundance of a variety of terrestrial mammal species in Borneo between selectively logged and unlogged forest, and to assess the impacts of edge effects. Our methods circumvent confounding factors that have plagued previous assessments of logging impacts by explicitly accounting for differential detection probability among habitats, separating the effects of hunting from those of logging-induced habitat disturbance, and explicitly measuring the distances over which edge effects occur. We found that mammalian carnivore species were either largely or completely confined to primary forest, although habitat use for the Sunda clouded leopard (Neofelis diardi) increased toward the ecotone. Several large ungulates, however, were either completely (elephant Elephas maximus and banteng Bos javanicus) or mostly (sambar Rusa unicolor) found in logged forest. This suggests that, in the absence of hunting, disturbed habitats can be important for the conservation of certain endangered and vulnerable species. Sambar and muntjac (Muntiacus spp.) both strongly avoided habitat edge in logged forest and primary forest, respectively. Lower habitat use by these species persisted 2–4km from the habitat boundary – farther than has been observed for the infiltration of other edge effects such as canopy desiccation. Such avoidance of ecotones implies that 20–40% of the intact primary forest habitat in our study area is actually degraded “edge habitat” from the point of view of primary forest specialists. Our results suggest that, while selectively logged forests retain conservation value for certain large mammal species, it is critical that thresholds in logging intensity be identified so as to avoid declines in habitat use by taxa, such as carnivores, which appear intolerant of intensive logging pressure.