Response of bat activity to land cover and land use in savannas is scale-, season-, and guild-specific

Abstract

Tropical savannas are biomes of global importance that are 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 may be vulnerable to such anthropogenic stresses. However, there is little information on the response of savanna bats to land-cover and land-use change, especially in Africa. This limits 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 how guild-specific (aerial, edge, and clutter forager) bat activity responded to both fine-scale metrics of vegetation structure and landscape-scale metrics of land-cover composition and configuration across the wet and dry seasons in a savanna in southern Africa undergoing rapid land-cover and land-use change. We found that all three guilds responded more strongly to landscape metrics than fine-scale vegetation structure, although the specific metrics varied between guilds. Aerial and edge bats responded most strongly to the percent savanna cover and savanna fragmentation in both seasons while clutter bats responded to percent rural cover in the wet season and percent water cover in the dry. All three guilds responded more strongly to the landscape in the dry season than the wet season. Our results show it is possible to conserve bats, and the ecosystem services they can provide, in savannas undergoing anthropogenic land-use and land-cover change but strategies to do so must consider foraging guild, large spatial scales, and seasonal variation in bat activity.

The Limpopo River Exerts a Powerful but Spatially Limited Effect on Bat Communities in a Semi-Arid Region of South Africa

“…The attraction of water bodies to bats in southern African agricultural-savanna mosaic landscapes is guild-, season-and scale-specific (Weier et al, 2018;Shapiro et al, 2019). For example, in the lowlying savanna region of Eswatini, in the dry season (but not the wet season), activity of clutter-feeding and clutter-edge bats (but not open-air feeders) responded positively to water (Shapiro et al, 2019).…”

“…The attraction of water bodies to bats in southern African agricultural-savanna mosaic landscapes is guild-, season-and scale-specific (Weier et al, 2018;Shapiro et al, 2019). For example, in the lowlying savanna region of Eswatini, in the dry season (but not the wet season), activity of clutter-feeding and clutter-edge bats (but not open-air feeders) responded positively to water (Shapiro et al, 2019). In a dry deciduous forest in central western Madagascar, bat activity at pools within a riverbed were significantly higher than forest and dry riparian habitats, but only for Vespertilionidae (clutter-edge) and Hipposideridae (clutter-feeding) bats, not for openair-feeding Molossidae (Bader et al, 2015).…”

“…Southern African savannas support a rich diversity of bats (Gelderblom et al, 1995;Monadjem et al, 2010aMonadjem et al, , 2010b. Bat community structure in savannas has been shown to be shaped by both abiotic and biotic factors acting at local and regional scales (Weier et al, 2016;Schoeman and Monadjem, 2018), as well as by land use and climate change (Taylor et al, 2013b;Smith et al, 2016;Foord et al, 2018;Mtset fwa et al, 2018;Weier et al, 2018;Shapiro et al, 2019).…”

Bat Species Richness and Community Composition along a Mega-transect in the Okavango River Basin

“…Members of the Rhinolophidae, Nycteridae and Hipposideridae, are also typically classified as clutter-feeders. In intact ecosystems, all feeding guilds should be present (high functional diversity), while anthropogenic impacts such as intensive agriculture may lead to a lower functional diversity due to a loss of canopy habitats for sensitive, clutter-feeding bats [26,27]. Recent studies have shown that the clutter-feeding guild and families belonging to this guild (the Rhinolophidae) are especially sensitive to land use changes such as agricultural expansion and urbanization [26,28].…”

“…Recent studies have shown that the clutter-feeding guild and families belonging to this guild (the Rhinolophidae) are especially sensitive to land use changes such as agricultural expansion and urbanization [26,28]. Shapiro et al [27] showed that the response of bat activity to anthropogenic pressure in tropical savannas is both season and guild dependent.…”