Logging drives contrasting animal body-size effects on tropical forest mammal communities

Abstract

Anthropogenic disturbance of tropical ecosystems can re-configure mammalian communities, frequently through a process of differential impact on animal species, whereby medium- and large-bodied animals are more impacted than small-bodied animals, which often are even favored. Here we examine if logging –a prevalent activity in the tropics– drives a pattern of differential defaunation in a Neotropical forest managed by a community of indigenous people. Using a match-paired design, we conducted mammalian surveys during four consecutive years in three independent sites, each one including (1) areas for logging practiced by Maya communities of the Yucatan Peninsula (selective and interspaced harvesting), and (2) adjacent areas set aside as reserves. We found that in logged areas the abundance of medium and large mammals decreased (4.3-fold, overall), while the abundance of small mammals increased (2.5-fold, overall). We posit that these changes result from a combination of factors, including: (1) facilitated access for hunters of medium- and large-sized game, comprising both predators (potentially leading to small-prey release) and competitors of small-bodied species; (2) changes in vegetation (e.g., more shelter and food for rodents); and (3) contrasting animal life history traits (population growth rate, home range size). We conclude that although non-intensive logging interventions have negative consequences for the mammalian community (for at least ten years after harvesting), the indigenous practices of rotational harvesting and maintaining reserves help to prevent the landscape-wide mammalian declines known to occur under large-scale industrial logging.