A comparative analysis of the breeding biology of the Red-billed Chough Pynhocorax pyrrhocorax and the Alpine Chough P. graculus coexisting in the Alps

We compare the breeding biology of a small population of Red-billed Chough Pyrrhocorax pynhocorax with that of the Alpine Chough P. graculus coexisting in the western Italian Alps. The analysis focused on nest site choice, timing of breeding, reproductive success and parental effort (assessed by means of behavioural indices such as food provisioning rates and time budgets inside and close to the nest). The Alpine Chough nested in a greater variety of sites: natural cliffs, windows of a dam, pot-holes and abandoned buildings; the Red-billed Chough used only natural cliffs. Laying dates also differed significantly, with the Red-billed Chough breeding one month earlier than its congener. Differences in the feeding ecology of those species might be responsible for the observed temporal partitioning, thus facilitating coexistence. Breeding success and reproductive behaviour were similar, and the species differed in only one out of eight breeding parameters. It is suggested that similar strong constraints on breeding behaviour have resulted in the similarities in behaviour seen in these species.