Responses to hawking attack and distress call sequences by bats in Saskatchewan

Abstract

Eavesdropping on acoustic signals can be an important decision-making tool for many animals. Despite how much research has gone into how bats use sound for orientation and foraging, surprisingly little research has focused on eavesdropping as a decision making and survival tool. I assessed how four insectivorous bats in North America, the big brown bat (Eptesicus fuscus), hoary bat (Lasiurus cinereus), silver haired bat (Lasionycteris noctivagans), and little brown bat (Myotis lucifugus) responded to conspecific and heterospecific call sequences. I played distress and aerial hawking attack sequences along Battle Creek in Southwest Saskatchewan, Canada and used acoustic detectors to determine whether there was a change in bat activity during playbacks. Call collection and playback experiments were conducted between June – August 2022 and 2023. I expected an overall increase in activity when I played back both conspecific and heterospecific call sequences for both call types, with some species-specific differences based on size and life history. However, I found that M. 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. I also found that while L. cinereus are attracted to conspecific hawking sequences, they are not attracted to conspecific distress sequences. They are, however, attracted to L. noctivagans distress sequences; but, repelled by L. noctivagans hawking attack sequences. L. noctivagans do not respond to conspecific or heterospecific distress calls, but are repelled by L. cinereus hawking sequences. My research highlights how little we know about how and why bats respond to call sequences and, by extension, how little we know about bat community relationships in general.