Breeding Biology of the Atiu Swiftlet

Abstract

The Atiu Swiftlet Aerodramus leucophaeus sawtelli builds most of its nests from lichen, fibre from the crown of the coconut tree and saliva. Nests were smaller and less often placed in total darkness than those of other species that also have two chicks. Most nests were built in September and the last chicks probably fledged in April. Both parents share the incubation of their two white eggs and both begin moulting their flight feathers while incubating. As well as replacing lost eggs and young broods some parents relaid after successfully fledging their first brood. The average weight of newly hatched chicks was 1.1 g and at the time of fledging (53 days later) was 9.5 g. Each brood was fed six times a day. Chicks do not have any of the parasitic louse flies that are common on other swiftlets in the south-west Pacific but they are killed by crabs. Atiu sustained 380 breeding Atiu Swiftlets during the season, which means the density was 7.1 ha per breeding bird.