Geographic diversification in the call repertoire of the genus Pyrrhocorax (Aves, Corvidae)

Abstract: We analysed the call repertoires of the Red-billed Chough (Pyrrhocorax pyrrhocorax) and the Alpine Chough (Pyrrhocorax graculus) across three continents (Europe, Asia, and Africa) for intraspecific and interspecific differences in call-repertoire size and discuss the factors that could have promoted its evolution. The overall call reper-toire of the Red-billed Chough was twice as large as that of the Alpine Chough, but the number of calls recorded in each population did not differ significantly between the two species. The greater fragmentation of the range of the Red-billed Chough possibly induced its remarkable call-repertoire diversification. Some populations (i.e., those from Ethio-pia, Central Asia, Canaries) had a peculiar call repertoire that overlapped very little with those from other regions; con-sequently, the overall numbers of call types within the species were heavily influenced by these unusual populations and were very large. The call-repertoire size and call-repertoire similarity of populations of both species were affected and constrained by geographic distance. More closely situated or continental populations tended to have a more similar pool of calls (this is probably due to mingling among close populations). Résumé: Nous avons analysé le répertoire des cris chez le Crave à bec rouge (Pyrrhocorax pyrrhocorax) et le Cho-card à bec jaune (Pyrrhocorax graculus) sur trois continents (Europe, Asie et Afrique) par estimation des différences intraspécifiques et interspécifiques dans l’importance du répertoire des cris et par examen des facteurs qui peuvent avoir favorisé son évolution. Dans l’ensemble, le répertoire des cris du Crave à bec rouge est deux fois plus important qu