The IBA is comprised of Tarrabool Lake and an unnamed swamp to the north-west of Tarrabool Lake on Eva Downs Station (unofficially titled Eva Downs Swamp). In wetter years, these two water bodies become broadly connected to form a single massive freshwater wetland of up to 275,000 ha. Tarrabool Lake and Eva Downs Swamp are seasonally inundated, but may retain water for 12 consecutive months (or more in the case of Tarrabool Lake) after major flood events. Tarrabool Lake is dominated by low sparse to open Coolibah woodland, with extensive open Lignum shrubland (often under Coolibah woodland) in the centre-east, large areas devoid of trees in the centre-north and centre-south, and smaller open areas elsewhere, and some patches of open Northern Bluebush shrubland. The heart of Eva Downs Swamp is dominated by open Belalie woodland, mostly in association with open Lignum shrubland, and is surrounded by open Northern Bluebush shrubland; and there is tall tussock grassland to the south-east, with some open Coolibah woodland on the southern margin. Ground-cover plants such as Schoenoplectus dissachanthus can grow prolifically on drying or marshy areas of the system, and Nardoo is common (DEWHA 2007; R. Jaensch pers. comm. 2007).
The IBA supports large numbers of waterbirds when conditions are suitable, e.g. up to 269,000 waterbirds may have been present during a major flood event in 2001-2002. At least 50 species of waterbird have been recorded, and 17 of these species are known to breed, in the IBA (Jaensch & Bellchambers 1997; Wetlands International, unpublished data provided by R. Jaensch). Species recorded in notable but sub-threshold numbers are Freckled Duck (84 on 29 March 2006), Great Egret (several thousand in 2001-2002 and 2006), Glossy Ibis (possibly more than 10,000 in March 2006) and Gull-billed Tern (1300 in 1995) (Jaensch & Bellchambers 1997; Wetlands International, unpublished data provided by R. Jaensch). Species observed in many thousands, but not confirmed to exceed thesholds, include the Magpie Goose, Plumed Whistling-Duck, Grey Teal, Hardhead and Intermediate Egret (R. Jaensch pers. comm. 2007). The nationally vulnerable Australian Painted Snipe bred at Tarabool Lake in 1993 (Jaensch 2003a), this representing the first breeding record for the species in the Northern Territory (R. Jaensch pers. comm. 2007). A breeding event involving 1500 pairs of Great Egret at Eva Downs Swamp in 2001 (Jaensch & Bellchambers 1997; Wetlands International, unpublished data provided by R. Jaensch) may be the largest documented breeding effort by this species in inland tropical Australia (R. Jaensch pers. comm. 2007).
Non-bird biodiversity: At least seven faunal species recorded in the Tarabool Lake-Eva Downs region are listed under international conventions or bilateral agreements protecting migratory animals .
Pressure/threats to key biodiversity
Undertake development of a wetlands management strategy with landholders to identify additional stock exclusion areas and appropriate management of wetlands to maintain conservation values (NRETA 2005). Such a strategy should include prescriptions for fire management and to minimise the impact of livestock on natural values. Develop a conservation agreement and concept plan with landholders to include the wetlands in the reserve system. In cooperation with landholders, research the value of the wetlands for potential nomination as a wetland of international importance under the Ramsar convention (NRETA 2005).
Conservation responses/actions for key biodiversity
Tarabool Lake and Eva Downs Swamp are listed on the Register of the National Estate and the Directory of Important Wetlands in Australia (DEWHA 2007) and are classified as sites of conservation significance by the Northern Territory Government (Harrison et al. 2009; Ward & Harrison 2009). Since 1993, Wetlands International has conducted irregular surveys of waterbirds following major flood events (R. Jaensch pers. comm. 2007). A 35 km stretch of Cresswell Creek, which lies north of the IBA but drains into Tarrabool Lake, was sprayed with herbicide in 2005 to treat Parkinsonia aculeata infestations. Follow-up work to treat infestations is ongoing with permanent points established to monitor the success of the program (Barkly Landcare and Conservation Association 2006; Harrison et al. 2009). Livestock are excluded from part of Eva Downs Swamp during periods of inundation. Fire on the tropical savannas is mapped continuously under the North Australia Fire Information Project. A number of tier 1 rangeland monitoring points are located in the Tarrabool Lake-Eva Downs Swamp region (Harrison et al. 2009).
Four pastoral leasehold properties (Anthony Lagoon, Rockhampton Downs, Brunchilly and Eva Downs) managed by companies including Australian Agricultural Company and Heytesbury Beef.
Site access / Land-owner requests
The IBA is located on privately-owned land with public access at the discretion of landholders.
Roger Jaensch of Wetlands International provided unpublished data, comments and interpretation on the habitat and waterbird information.
BirdLife International (2023) Important Bird Areas factsheet: Tarrabool Lake-Eva Downs Swamp System. Downloaded from
http://www.birdlife.org on 02/04/2023.