The influence of social dominance on calling rate in the Large-billed Crow (Corvus macrorhynchos)

Abstract

Individual animals of social species that form dominance hierarchies use status signals to advertise their dominance status to conspecifics. Bird species often have a visual status signal known as a “badge of status.” However, the hierarchies of some social species are fluid, and dominance status may change depending on the composition of the group. In such situations, vocal signals are more suitable as a status signal because they are readily modifiable by the signaler. In this study, we investigated the relationship between social dominance rank and calling rate in the Large-billed Crow (Corvus macrorhynchos) by observing a captive flock of Large-billed Crows and determining the dominance rank of each individual. The number of vocalizations each individual produced during the study period were also recorded. Our results revealed that there was a clear linear dominance hierarchy within the flock and that more dominant crows produced sequential-note calls more frequently than their subordinate counterparts. Contact call rate, however, was not affected by dominance status. These results suggest that sequential-note calls function as status signals in groups of Large-billed Crows.