The social context of contact calls by rooks (corvus frugilegus)

Communication is the link between individuals of one species and represents the essence of social life. Vocal communication is one of the most studied forms of information exchange, although it also comes with interspecific barriers that are still tricky to overcome. While we are able to understand the meaning of another human’s words, we fail to understand an animal’s utterances. Among these, bird song has become a field of particular interest. However, little is known yet about many species’ vocalizations, and even less about their significance or how different factors influence them. The presented study establishes the vocal repertoire of a group of rooks and further investigates the importance of contact calls between partners in an experiment. We found that test subjects and other group members produced more contact calls after than before partners had been separated from each other, indicating stress induced by physical isolation and/or the lack of visual contact as an important factor influencing the call frequency. Separating certain individuals seemed to affect the group differently, which indicates that the ‘importance’ of the animal to the group influences the group call rate. In this study, we have shown how social and environmental factors play a role in vocal communication in birds.