Burrow occupancy and related behaviour of broad-billed prions Pachyptila vittata on South East (Rangatira) Island, Chatham Islands, New Zealand

Abstract

Burrow competition is occurring between broad-billed prions (Pachyptila vittata) and other small burrowing seabirds on South East (Rangatira) Island, Chatham Islands, New Zealand. This competition has a negative impact on the endangered Chatham petrel (Pterodroma axillaris) population. Seventy-seven broad-billed prion burrows were monitored nightly during the breeding season in 1996 and the non-breeding season in 1997 to determine burrow use patterns. From the total 246 broad-billed prions that were recorded in the non-breeding season 83% were returning breeders. Up to 10 broad-billed prions made use of individual burrows in the nonbreeding season. Some movement of established breeding broad-billed prions between burrows in the nonbreeding season occurred. Behavioural observations during the non-breeding season showed that broad-billed prions defended their burrow from others, spent time prospecting for burrows, pair bonded and attempted to establish ownership of burrows. Potential management strategies for broad-billed prions are discussed.