Forest conversion to cattle ranching differentially affects taxonomic and functional groups of Neotropical bats

Abstract

Understanding the effects of land conversion for livestock grazing on species diversity and functional groups continues to be urgently needed to assess how ranching affects animal assemblages and provide guidelines for managing landscapes under this omnipresent type of land use. Given Neotropical bats' high diversity of feeding habits and flying abilities, and that they play multiple, important ecological roles in ecosystems, they are an ideal study system to address such a need. We investigated the effects of livestock ranching on Neotropical bat species and functional groups composition via meta-analyses of published information. We used the odds-ratio metric to compare the frequency of occurrence of bat species in old-growth forest vs. areas influenced by livestock. Our results show no effects when considering bats as a group. However, significant effects emerge when they are assessed separately, on the basis of taxonomic family, feeding habit, conservation status and flying ability, showing that considering bats as a black box mutes relevant patterns. Molossid and phyllostomid species with high movement ability or omnivorous habit showed an increased frequency in livestock areas. In contrast, frugivores and aerial insectivores with low movement ability, carnivores, gleaning insectivores, nectarivores, sanguivores and species considered under some degree of extinction risk were significantly more frequent in old-growth forest. Overall, our results support that areas converted for livestock production retain only a subset of the Neotropical bat functional diversity while most of the functional groups are negatively impacted. Such heterogeneity of responses seems critical for our understanding of the effects of land use change on animal communities.