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The IBA is identical to the area of Benger Swamp, which is wholly contained within Benger Swamp Nature Reserve, and which is located approximately 12 km south-south-west of Harvey in Western Australia. Benger Swamp is an isolated seasonally inundated freshwater marsh dominated by extensive beds of bulrush, with areas of grassland and sedgeland and fringing stands of Melaleuca scrub. Water levels at the swamp are artificially manipulated via a system of drains and a check-gate with inflow coming from nearby farms. The original motivation for water management was to drain the swamp to permit the seasonal sowing of agricultural crops. Today, the management of water levels is intended to maintain the natural ecological values of the wetland and includes ploughing to maintain zones of open water which are free of Typha vegetation. The climate is temperate with warm dry summers and cool winters.
More than 50 species of waterbird have been recorded at Benger Swamp, making it one of the most diverse sites for waterbirds in Western Australia. This total includes 12 breeding species and at least seven species that are listed under international treaties for migratory taxa (DEWHA 2008a, b). Another 15 species probably breed at the site but are not confirmed to do so (DEWHA 2008a). The maximum number of waterbirds counted at the site was 4300 in December 1985 (DEWHA 2008a); numbers regularly exceed 1000 when conditions are most suitable (Jaensch et al. 1988). The most abundant species at the swamp are Pacific Black Duck (maximum count 1500 in November 1983) and Hardhead (maximum count 1500 in November 1982). The swamp is a breeding site for Freckled Duck (maximum count of 100 in September 1962; counts of up to 13 in the 1980s) and Musk Duck (maximum count 84) (Jaensch et al. 1988; DEWHA 2008a). The swamp also supports regionally significant numbers of White-faced Heron, Australian White Ibis, Spotless Crake and Purple Swamphen; large numbers of Clamorous Reed-Warbler and Little Grassbird; and the only known population of Southern Emu-wren on the Swan Coastal Plain between Perth and Bunbury (Watkins et al. 1987; Jaensch et al. 1988; DEWHA 2008a, b). Other notable species which have been recorded in the IBA are the biome-restricted Western Rosella and Red-capped Parrot (Atlas of Australian Birds database).
Non-bird biodiversity: The IBA supports at least three species of frog and at least one species of fish, tortoise and mammal. Invertebrates are abundant in late spring (Watkins et al. 1987; DEWHA 2008b).
BirdLife International (2020) Important Bird Areas factsheet: Benger Swamp. Downloaded from http://www.birdlife.org on 28/02/2020.