Group composition and reproductive success of cooperatively breeding white-winged choughs (Corcorax melanorhamphos) in urban and non-urban habitat

Abstract

White-winged choughs (Corcorax melanorhamphos, Corcoracidae) are a common, breeding resident in and around the city of Canberra in the Australian Capital Territory. We compared five measures of reproductive success between the urban and non-urban populations of choughs to investigate the effect of urbanization on this cooperatively breeding species. Urban choughs initiated breeding earlier than their non-urban counterparts and were more likely to suffer nest failures. However, there was no difference in the number of successful nests in a season or the number of fledglings produced per successful nesting attempt. A greater proportion of fledglings survived their first 12 months in the non-urban habitat. We suggest that increased rates of nest predation and fledgling mortality in the urban environment may have a negative effect on reproductive success and remove any advantage that might be gained through a longer breeding season. Possible effects of urbanization on the social and genetic structure of white-winged choughs are also discussed.