Ecological drivers of selection for remnant forest habitats by an insectivorous bat in a tropical, human-modified landscape

Abstract

Biodiversity conservation outside protected areas reduces the impacts of anthropogenic activity and improves the benefits of ecosystem services. However, conservation also requires identification and preservation of habitats used by organisms in human-modified landscapes. Since such landscapes are heterogeneous, with fragmented habitats, space use decisions of species are expected to be non-random and dependent on resource distribution. We examined habitat selection by an insectivorous bat, Megaderma spasma in a human-modified landscape, and tested whether insect resources in the habitat drive its selection. Using high-resolution satellite imagery, we classified a 36 km2 area of a biodiversity hotspot in Western Ghats, India, into three major habitat categories: forest, plantation, and open habitat. We then tracked 18 bats across an average of 7.33 ± 3 days using radio telemetry and sampled insect resources in forests and plantations. Compositional analysis suggested that Megaderma spasma showed selection for forest habitats. Mixed-effects conditional logistic regression showed that the odds of bats using forest habitats was on average 5.87 times higher than open habitats. Apportionment analysis of insects trapped in forests and plantations showed that habitat type contributed only 0.4% of the difference in diversity at the insect order level, suggesting that insect resources did not differ between the two habitats. However, the relative abundance of one of the bat's prey (katydids of the genus Mecopoda) was significantly higher in forest habitats than in plantations, suggesting that prey abundance in forests may drive the bat's habitat selection. Remnant forest habitats are important resources for insectivorous bats and need to be preserved for maintaining ecosystem functions in human-modified landscapes.