A comparative analysis of the breeding biology of the Red-billed Chough Pyrrhocorax 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 pyrrhocorax with that of the Alpine Chough P graculus coexistin g in the western Italian Alps. The analysis focused on nest site choice, ti ming of breeding, reproductive success and parental effort (assessed by mea ns of behavioural indices such as food provisioning rates and time budgets inside and close to the nest). The Alpine Chough nested in a greater variet y of sites: natural cliffs, windows of a dam, pot-holes and abandoned build ings; the Red-billed Chough used only natural cliffs. Laying dates also dif fered significantly, with the Red-billed Chough breeding one month earlier than its congener. Differences in the feeding ecology of those species migh t 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 su ggested that similar strong constraints on breeding behaviour have resulted in the similarities in behaviour seen in these species.