Antiphonal calling allows individual discrimination in white-winged vampire bats

Mother bats use pup contact calls ('isolation calls') to find and recognize their young. In white-winged vampire bats, Diaemus youngi, adults produce social calls that are structurally similar to the pup isolation calls of many other bat species. In addition, D. youngi seem to exchange these calls in a duet-like fashion. To determine whether calls elicit precise antiphonal responses, we simultaneously recorded social calls from groups of four captive bats vocally interacting. To examine call function, we conducted isolation experiments, permuted discriminant function analyses (pDFA) of individual variation in call structure, and a habituation-discrimination playback experiment. We found that adult D. youngi call when isolated, and their social calls attract conspecifics and elicit antiphonal responses. Bats called within 500 ms of a conspecific more than expected based on a random calling model. These findings are the first evidence of antiphonal calling among adult bats. We found significant individual variation in call structure, and show that bats can discriminate individual identity using social calls alone. We hypothesize that D. youngi use these antiphonal contact calls to mediate social interactions among individuals outside the roost.