Crows cross-modally recognize group members but not non-group members.

Recognizing other individuals by integrating different sensory modalities is a crucial ability of social animals, including humans. Although cross-modal individual recognition has been demonstrated in mammals, the extent of its use by birds remains unknown. Herein, we report the first evidence of cross-modal recognition of group members by a highly social bird, the large-billed crow (Corvus macrorhynchos). A cross-modal expectancy violation paradigm was used to test whether crows were sensitive to identity congruence between visual presentation of a group member and the subsequent playback of a contact call. Crows looked more rapidly and for a longer duration when the visual and auditory stimuli were incongruent than when congruent. Moreover, these responses were not observed with non-group member stimuli. These results indicate that crows spontaneously associate visual and auditory information of group members but not of non-group members, which is a demonstration of cross-modal audiovisual recognition of group members in birds.