MENDON�A, MT; SCHMAEMAN, CN; GRILLIOT, ME; Auburn University, Auburn, AL: Mechanisms for sex recognition in the big brown bat: potential use of pheromones and ultrasonic vocalizations

A variety of studies in bats have demonstrated the use of pheromones for mother-young recognition, roost mate recognition, and male-male recognition in harem systems. Additionally, the use of ultrasonic communication has been also been proposed to play a role in mother-young interaction as well as individual recognition. Surprisingly, neither of these sensory modes has been implicated in male-female recognition or courtship and mating behavior. During the mating season (Jan-March), we tested sex-recognition of male and female big brown bats. We placed individual male and female bats in a Y-maze and exposed them to either (1) same sex vs. blank, (2) opposite sex vs. blank, or (3) same sex vs. opposite sex. Male bats preferentially chose (70%, n = 28) and spent significantly (p = 0.03) longer periods of time in the female arm of the maze when presented with male vs. female choice. Additionally, males tended to choose (66%, n = 12) and spend more time (p = 0.1) in the female arm when presented with a female vs. blank choice. Males significantly chose (100%, n = 6) and spent more time (p = 0.0006) in the male arm when presented with male vs. blank choice. These results suggest sex recognition based on pheromonal cues or ultrasonic cues. We have found significant sex differences in several ultrasonic call parameters which could function in sex recognition as well as courtship and mating.