Colony-specific foraging behaviour and co-ordinated divergence of chick development in the wedge-tailed shearwater Puffinus pacificus

Abstract

We examined divergence in foraging, provisioning and chick developmental patterns between wedge-tailed shearwaters Puffinus pacificus breeding at a temperate (Lord Howe Island) and sub-tropical (Heron Island) location. We aimed to evaluate the potential for different foraging environments to cause co-ordinated adaptive divergence in these characteristics. Adult foraging and provisioning behaviour differed significantly between locations, reflecting lower near-colony resource availability at Heron Island. Chick developmental patterns also differed significantly between locations. Overall, chicks at Lord Howe Island grew faster and had greater skeletal growth per gram of food delivered. In contrast, chicks at Heron Island exhibited greater body mass gains per gram of food delivered. Based on previously observed physiological or facultative responses to changes in provisioning rates in seabirds and long-term patterns of primary productivity at each location, we propose these developmental differences reflect colony-specific physiological adaptations to differences in long-term provisioning rates. If so, our results suggest co-ordinated environmentally determined divergent coevolution of chick and adult life-history parameters between these 2 locations. © Inter-Research 2005.