Mixed support for the attractiveness of feeding buzzes and distress calls within and across four vesper bat species

Eavesdropping on acoustic signals plays a crucial role in decision making for many animals. While much research has focused on how bats use sound for orientation and foraging, surprisingly little has focused on how eavesdropping impacts survival and decision making. We examined how four insectivorous bat species in North America, the big brown bat, Eptesicus fuscus , silver-haired bat, Lasionycteris noctivagans , hoary bat, Lasiurus cinereus , and little brown bat, Myotis lucifugus , respond to conspecific and heterospecific call sequences. Between June and August of 2023, we played distress and aerial hawking attack sequences along Battle Creek in southwest Saskatchewan, Canada, and used acoustic recorders to measure any changes in bat activity during and just after the playbacks. We hypothesized that bat activity would increase in response to both conspecific and heterospecific call sequences, with species-specific differences based on size and life history. However, we found that while L. cinereus were attracted to conspecific hawking sequences (= feeding buzzes), they were not attracted to any other conspecific or heterospecific attack or distress sequences. Lasionycteris noctivagans , in turn, were repelled by L. cinereus hawking sequences but did not respond to conspecific or heterospecific distress calls. Myotis lucifugus did not respond to conspecific or heterospecific distress call or hawking attack sequences. This is in contrast with previous studies that have concluded M. lucifugus is attracted to conspecific vocalizations. Our findings underscore our limited understanding of how bats respond to call sequences and, more generally, bat community relationships. • We hypothesized that bat activity would increase in response to other bats' sounds. • Our results instead suggest bats may be attracted, repelled or indifferent. • These differences are based on the sounds heard (feeding buzzes vs distress calls). • And the species listening and the species being listened to.