Bats resolve conflicting sensory information for individual recognition

: Recognizing conspecifics individually is paramount in shaping animal societies,1,2,3,4,5,6,7,8 and vocal signals can play an important role in this process.9,10,11,12 Humans13 and some other species14,15,16,17,18 identify individuals by integrating information from different sensory modalities. This ability can facilitate stable relationships, kin recognition, and cooperative interactions.5,6,7,8 Studies of individual recognition in wild animals remain rare.19,20,21 Here, we present experimental evidence that wild greater sac-winged bats, Saccopteryx bilineata, a species with stable social groups, high roost fidelity, and a preference for well-lit day-roosts,22,23 recognize individual group members. In many species,24,25,26,27,28,29 including bats,30,31,32,33,34 individuals produce distress calls when physically constrained by a predator. We show that distress calls of S. bilineata encode individual signatures. Further, we conducted playback experiments at the day-roosts to test for individual recognition. We used a violation-of-expectation paradigm in which the subject is presented with information for individual identification aligning or conflicting with one another.17 When individual recognition occurs, the subject may show heightened attention to conflicting information17,19,21 or the plausible association.18,35,36 Remarkably, roosting bats only approached the source of a distress call under plausible conditions-when the supposed caller was absent from the roost. When confronted with an impossibility-the supposed caller was in the roost and its voice simultaneously came from elsewhere-bats ignored the playback entirely. This striking ability to detect and reject such inconsistencies reveals a high level of cognitive sophistication, as these bats reconcile what they see or smell with what they hear to assess the reality of a situation.