Functional trait filtering of aerial insectivorous forest bats in Amazonian cattle-dominated landscapes

The conversion of forest to cattle pasture is a major driver of biodiversity loss, particularly in the tropics. Bats provide essential ecosystem services and are widely used as indicators of ecosystem integrity, yet how functional traits mediate their vulnerability to land-use change remains poorly understood. Here, we combined bioacoustic surveys with functional trait data to investigate the relationship between functional traits and sensitivity to land-use change in aerial insectivorous bats across forest and cattle-farmed sites in Mato Grosso State, Brazil. We sampled bats using passive acoustic recorders across 20 cattle farms, recording 66,301 bat passes representing 28 sonotypes. Regression models revealed no differences in taxonomic or functional diversity between forest and pasture sites. However, multivariate RLQ and fourth-corner analyses identified strong associations between bat activity, functional traits, and environmental variables. Wing morphology, echolocation call structure, and foraging strata emerged as key predictors of sensitivity to land-use change. Understory and canopy foragers with low relative wing loading and aspect ratio, and call characteristics associated with cluttered environments, were positively associated with forest cover. In contrast, above-canopy foragers with higher wing loading and aspect ratio were associated with open, fragmented pasture landscapes. These findings suggest that forest conversion does not necessarily reduce overall bat diversity, but instead filters species according to functional traits, disproportionately affecting clutter-adapted bats and the ecosystem services they provide. Beyond maintaining forest cover, conservation strategies in agricultural landscapes should prioritize reducing fragmentation to safeguard bat functional diversity and associated ecosystem services.