Choice experiments demonstrate that male big brown bats (Eptesicus fuscus) prefer echolocation calls of high copulatory females

It generally is accepted that bats emit ultrasonic vocalizations that function for echolocation purposes as well as for communication. We tested whether male or female big brown bats (Eptesicus fuscus) responded to variation in echolocation calls of the opposite sex in a manner that would suggest calls are used in a mating context. We presented 31 female and 10 male big brown bats with ultrasonic playbacks of differentially mating (i.e., high frequency copulators = HM versus low-frequency copulators = LM) individuals of the opposite sex. We measured 1) which side of the arena each subject selected first (HM versus LM), and 2) duration spent (seconds) on each side of the arena (HM versus LM). For both of these measures (i.e., first choice and duration) male subjects were more likely to select the echolocation calls of HM females, but the same respective tests determined that female subjects did not select echolocation calls of frequently copulating males over calls of infrequently copulating males. These results support the possibility that the echolocation calls of big brown bats provides information about the sender that may be important in a mating context.