Benger Swamp (26476)
Australia, Australasia
Site overview
KBA status: confirmed
Year of last assessment: 2009
National site name: Benger Swamp
Central coordinates: Latitude: -33.1717, Longitude: 115.8357
System: freshwater, terrestrial
Elevation (m): 13 to 15
Area of KBA (km2): 3.55438
Protected area coverage (%): 99.99
KBA classification: Global/Regional TBD
Legacy site: Yes
Site details
Site description: 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.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance because it meets one or more previously established criteria and thresholds for identifying sites of biodiversity importance (including Important Bird and Biodiversity Areas, Alliance for Zero Extinction sites, and Key Biodiversity Areas)
Additional biodiversity: 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).
Other site values: State government; private (freehold).
Habitats
Land use: nature conservation and research
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Wetlands(Inland) | 100 |
Threats
Summary of threats to biodiversity at KBA: Manage water levels to maintain habitat for the Australasian Bittern and other waterbirds. Monitor water quality and initiate remedial action if salinity or nutrient levels exceed acceptable thresholds. Control exotic plant and animal species.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Natural system modifications | Dams & water management/use | Abstraction of surface water (agricultural use) | Ongoing |
| Biological resource use | Hunting & collecting terrestrial animals | Persecution/control | Ongoing |
| Agriculture & aquaculture | Annual & perennial non-timber crops | Agro-industry farming | Ongoing |
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Named species | Ongoing |
| Pollution | Agricultural & forestry effluents | Type Unknown/Unrecorded | Ongoing |
| Natural system modifications | Fire & fire suppression | Increase in fire frequency/intensity | Only in the future |
| Natural system modifications | Fire & fire suppression | Suppression in fire frequency/intensity | Only in the future |
| Climate change & severe weather | Droughts | Ongoing |
Additional information
References: DEWHA (2008a) A Directory of Important Wetlands in Australia. Benger Swamp - WA072. Downloaded from http://www.environment.gov.au/water/publications/environmental/wetlands/database/ in December 2008. DEWHA (2008b) Australian Heritage Database. Benger Swamp, Swamp Rd, Benger, WA, Australia. Downloaded from http://www.environment.gov.au/cgi-bin/ahdb/search.pl in December 2008. Jaensch, R.P., Vervest, R.M. and Hewish, M.J. (1988) Waterbirds in Nature Reserves of South-western Australia 1981-1985: Reserve Accounts. RAOU Report 30. RAOU, Canning Bridge, WA. Watkins, D., Clarke, J., Lane, J., & Moore, S. (1987) Benger Swamp Nature Reserve Management Plan. Management Plan 7. Western Australian Department of Conservation and Land Management.
Contributors: Roger Jaensch of Wetlands International and Peter Taylor provided data and comments on the nomination.