Effects of White-Nose Syndrome on Bat Diets and Interspecific Competition

Abstract

Competition is commonly invoked to explain variation in abundance, activity patterns, and resource use, but is difficult to detect in nature. Introduction of white-nose syndrome (WNS) in bats provides a natural experiment to test the impact of interspecific competition on bat communities. Acoustic monitoring at locations in Southern Ontario showed an increase in activity of Big Brown Bats (Eptesicus fuscus) and corresponding decline in the activity of Little Brown Myotis (Myotis lucifugus), following the introduction of WNS. Next generation sequencing of bat stomachs and guano in Southern Ontario before and after WNS allowed for the characterization of diet changes of these species. As a function of competitive release, E. fuscus consumed a wider breadth of prey and many of the insect species once consumed by M. lucifugus, including several pest insects. These results suggest that interspecific competition has a detectable effect on bat communities in Southern Ontario.