|Most recent IBA monitoring assessment|
|Year of assessment||Threat score (pressure)||Condition score (state)||Action score (response)|
|For more information about IBA monitoring please click here|
The IBA consists of the entire archipelago of about 150 islands, islets and rocks most of which are used by seabirds for breeding. Major concentrations of breeding seabirds on Pelsaert (500,000+ pairs), Wooded, Morley and West Wallabi (1,000,000 Wedge-tailed Shearwater burrows) Islands. Other important islands include East Wallabi, Dick, Long, Gilbert, Helms, Leo, Sandy, Shearwater, Coronation and Lagoon Islands for Fairy Tern; and Pelsaert, Jon Jim, Square, Dick, First Sister and Post Office Islands for Roseate Terns. Of 192 islands surveyed in 2006, 148 (77%) had breeding seabirds. The three main island groups are the Wallabi, Easter and Pelsaert groups. The largest island is the 600 ha West Wallabi which is dominated by limestone pavement. Wooded and Morley are neighbouring islands in the Easter group; Wooded (19 ha) and Morley (9 ha) are limestone islands with central lagoons. Pelsaert, the southern-most island in the group, is a 120 ha coral cay. The archipelago comprises a mixture of limestone continental islands and sand or coral cays. Annual average rainfall is about 500 mm. The island group is a multiple purpose reserve for "Conservation of Flora & Fauna, Tourism & for Purposes Associated with Fishing Industry" vested in the WA Minister for Fisheries, managed by the WA Department of Fisheries.
There have been two notable counts of Pied Cormorant: 550-900 pairs on nine islands in 1991 (Fuller et al. 1994) and 1436 pairs on eight islands in 2006/07 (Surman & Nicholson 2007). The islands also support the largest breeding colonies in Western Australia of Little Shearwaters, White-breasted Sea-Eagles (estimated 25 pairs), Osprey (estimated 42 pairs), Caspian Terns, and Crested Terns (Storr et al. 1986; Surman & Nicholson 2007). Breeding participation and success for many species greatly influenced by the Leeuwin Current; in some years breeding greatly reduced.
Non-bird biodiversity: Tammar Wallaby Macropus eugenii and Southern Bush Rat Rattus fuscipes occur on East and West Wallabi Islands. Endemic subspecies of Spiny-tailed Skink Egernia stokesii stokesii occurs on several islands.
BirdLife International (2021) Important Bird Areas factsheet: Houtman Abrolhos. Downloaded from http://www.birdlife.org on 18/01/2021.