A survey of the breeding seabirds and migratory shorebirds of the Houtman Abrolhos, Western Australia

A complete survey of the numbers and breeding stages of seabirds, resident and migratory shorebirds and raptors at the Houtman Abrolhos Islands, central west coast, Western Australia, was undertaken. One hundred and ninety two (192) islands, islets and rocks were surveyed over 21 days in December 2006. Seabird nesting habitat was mapped in its entirety for those islands considered as significant breeding areas (i.e. Pelsaert Island, Leo Island) and estimates of both breeding and roosting seabirds were made for each island. Notes on the stage of breeding were also taken, and where applicable, eggs were measured and weighed for some species to obtain breeding dates. Monitoring transects were established on West Wallabi and Pelsaert Islands to monitor longer term changes in the nesting density of the Wedge-tailed Shearwater Ardenna pacifica, Lesser Noddy Anous tenuirostris melanops, Common (Brown) Noddy Anous stolidus and Sooty Tern Onychoprion fuscata. The Lesser Noddy transects had been previously established by Fuller and Burbidge (1992), and were used again for comparative purposes. We recorded 14 species of seabirds, 16 species of migratory shorebirds, three resident shorebirds and two raptors during this survey. Of these, 14 species of seabirds, three resident shorebirds and the two raptors were breeding. These breeding populations are considered significant in a regional and national context. Of the 192 islands surveyed, 148 (77%) had breeding seabirds.