Distribution and abundance of the white-faced storm petrel (Pelagodroma marina) in Victoria

Habitat loss and modification is a major factor driving reductions of seabird populations. The white-faced storm petrel (Pelagodroma marina) is restricted to three breeding colonies within Victoria: Mud Islands and South Channel Fort in Port Phillip Bay, and Tullaberga Island off Mallacoota. The numbers of storm petrels breeding on Mud Islands and South Channel Fort have declined considerably, possibly a result of the significant vegetation changes, together with increases in local populations of other species of birds, most notably, silver gulls (Larus novaehollandiae). On Mud Islands the breeding area available to the storm petrels appears to be limited by the recent arrival of the Australian white ibis (Threskoirnis molucca), and straw-necked ibis (T. spinicollis) which now breed on the islands in large numbers (approximately 15,000 pairs). The impact of these changes on the storm petrels is poorly understood. The current status of storm petrels at Tullaberga Island is unknown. This study estimated the size of the breeding population at all three sites by determining burrow densities, and a burrow-scope was used to determine occupancy. Burrow density was found to be related to vegetation type and other habitat factors. This study has highlighted important information on the breeding habitat of the white-faced storm petrel and the implications for management are discussed.<br>