Aspects of the breeding ecology of the North Island little shearwater Puffinus assimilis haurakiensis

Abstract

Aspects of the breeding ecology of the North Island little shearwater Puffinus assimilis haurakiensis were studied on Lady Alice Island during the 1994 breeding season. Burrows with banded breeding birds were monitored throughout the breeding season to the fledgling stage. Details of the mating, pre‐laying exodus, incubation and chick rearing periods are presented. These include timing of breeding, length of incubation shifts, weight changes during incubation, and chick growth parameters. Little shearwaters showed a very high level of breeding asynchrony, and we suggest that this is due to their relatively short breeding season, and the fact that they are non‐migratory. Several aspects of the chick‐rearing stage, including frequent feeding of chicks, were not compatible with theories that fat deposits in Procellariiform chicks are an adaptation either to an unreliable food supply, or to stochastic food provisioning by individual adults. We suggest that, unlike other species of Procellariiformes, the little shearwater has access to a steady and predictable food supply. © 2000 Taylor and Francis Group, LLC.