Abstract:
Tropical savannas are biomes of global importance under severe pressure from anthropogenic change, including land-cover and land-use change. Bats, the second-most diverse group of mammals, are critical to ecosystem functioning, but vulnerable to such anthropogenic stresses. There is little information on how savanna bats respond to land cover and land use, especially in Africa, limiting our ability to develop conservation strategies for bats and maintain the ecosystem functions and services they provide in this biome. Using acoustic monitoring, we measured guild-specific (aerial, edge, and clutter forager) responses of bat activity to both fine-scale vegetation structure and landscape-scale land-cover composition and configuration across the wet and dry seasons in a southern African savanna undergoing rapid land-cover and land-use change. Responses were guild- and season-specific but generally stronger in the dry season. Aerial and clutter bats responded most strongly to landscape metrics in the dry season (positive responses to savanna fragmentation and water cover, respectively) but fine-scale metrics in the wet season (positive responses to water cover and grass cover, respectively). Edge bats responded most strongly (negatively) to the distance to water in the dry season and fine-scale shrub cover in the wet season. Our results show it is possible to maintain high levels of bat activity in savanna mosaics comprised of different land covers and land uses. Bats, and the ecosystem services they provide, can be conserved in these changing landscapes, but strategies to do so must consider foraging guild, spatial scale, and seasonal variation in bat activity.
