Differences in habitat selection between Chatham petrels (Pterodroma axillaris) and broad-billed prions (Pachyptila vittata): implications for management of burrow competition

The Chatham petrel (Pterodroma axillaris) is an endangered species restrict ed to a single population on South East Island, Chatham Islands, New Zealan d. The key threat to Chatham petrel breeding success is interference with c hicks by broad-billed prions (Pachyptila vittata) prospecting for burrows f or their oncoming breeding season. This burrow competition has resulted fro m alteration to breeding habitat by humans throughout the Chatham Islands. Understanding habitat preferences may enable managers to manipulate habitat to reduce burrow competition and will be essential in order to translocate Chatham petrels to a proposed second colony. Habitat characteristics surro unding both Chatham petrel and broad-billed prion burrows were quantified a nd selection ratios compared. Both Chatham petrels and broad-billed prions selected habitat factors associated with mature forest. Chatham petrels avo ided a large number of habitat characteristics, which suggests they were ha bitat specific, and their preferred habitat is now limited. Broad-billed pr ions used a wide range of habitat characteristics, which suggests they are not habitat specific. This study recommends that selection values be used w hen deciding on the best location to establish a second Chatham petrel colo ny.