|Most recent IBA monitoring assessment|
|Year of assessment||Threat score (pressure)||Condition score (state)||Action score (response)|
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The IBA comprises a system of wetlands around Lake Muir in Western Australia, which collectively support a significant population of Australasian Bittern. It includes the following wetlands with Australasian Bittern records in the 2000s: Kulunilup Swamp, Bokarup Swamp, Cobertup Swamp, Byenup Lagoon, Tordit-Gurrup Lagoon, Geordinup Swamp and Poorginup Swamp. The wetlands captured by the IBA are shallow with extensive beds of dense sedgeland and fringing stands of shrubland and woodland. Additional wetlands in the system may be included in the IBA if they are shown to provide suitable habitat for bitterns, including swamps around Unicup Lake, where bitterns have been seen. Counts of up to two Australasian Bittern were made at Yarnup Lagoon in 1981-1985 (Jaensch et al. 1988), but Yarnup Lagoon has been excluded from the IBA because conditions are no longer considered suitable for bitterns. Lake Muir has been excluded from the IBA as it is unsuitable for bitterns but it has supported large numbers of Australian Shelduck and may prove to be globally significant for that species. .The Lake Muir region has a warm Mediterranean climate.
More than 40 species of waterbird have been recorded in the IBA. An estimated 12,000 Australian Shelduck were observed at Tordit-Garrup Lagoon in December 1982 when conditions at nearby Lake Muir were unsuitable for the species. Other species recorded in notable numbers are Pacific Black Duck (758 in November 1987 at Byenup Lagoon) and Hardhead (550 in March 1989 at Tordit-Garrup Lagoon). The system also supports regionally significant numbers of Australasian Darter (up to 20 at Byenup Lagoon) and Australian Little Bittern (a count of seven at Yarnup Lagoon) (Jaensch 1984; Jaensch and Vervest 1988; Jaensch et al. 1988; DEWHA 2008a). Terrestrial species recorded in the IBA include Long-billed Black-Cockatoo, Western Rosella, Red-capped Parrot, Western Corella, Elegant Parrot, Red-winged Fairy-wren, White-breasted Robin and Western Yellow Robin (Atlas of Australian Birds database).
Non-bird biodiversity: The IBA supports more than 90 taxa of invertebrates and a small number of native fish species (Storey 1998; DEWHA 2008a).
BirdLife International (2019) Important Bird Areas factsheet: Muir-Unicup Wetlands. Downloaded from http://www.birdlife.org on 17/01/2019.