Current view: Text account
Site description (2008 baseline):
Site location and context
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).
Pressure/threats to key biodiversity
Continue to undertake control of feral pigs, horses and deer. Determine the impacts of exotic species on Australasian Bitterns and their habitat and develop corrective actions where necessary.
Conservation responses/actions for key biodiversity
All of the wetlands in the IBA are located within state conservation reserves. Some are included in the Muir-Byenup System, which is recognised as a wetland of international importance under the Ramsar convention. Lake Muir and associated wetlands are listed on the Register of the National Estate and are collectively classified as 'Key Wetlands and Natural Diversity Catchment' under the Salinity Action Plan for Western Australia. Actions have been taken to improve water quality and to control numbers of feral pigs in the Lake Muir catchment (DEWHA 2008a, b).
Numerous - see separate section.
Western Australian State government with management the responsibility of Department of Environment and Conservation.
Roger Jaensch of Wetlands International and Peter Taylor provided data and comments. Roger Hearn and Ian Wheeler of DEC supported surveys of bitterns.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Muir-Unicup Wetlands (Australia). Downloaded from
https://datazone.birdlife.org/site/factsheet/muir-unicup-wetlands-iba-australia on 27/12/2024.
