Tarrabool Lake - Eva Downs Swamp System
Encyclopedia
The Tarrabool Lake - Eva Downs Swamp System is an ephemeral wetland complex lying on the west of the Barkly Tableland region in the Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...

 of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. It is listed on Australia’s Register of the National Estate
Register of the National Estate
The Register of the National Estate is a listing of natural and cultural heritage places in Australia. The listing was initially compiled between 1976 and 2003 by the Australian Heritage Commission. The register is now maintained by the Australian Heritage Council...

 and on the DIWA wetland directory
A Directory of Important Wetlands in Australia
A Directory of Important Wetlands in Australia is a list of wetlands of national importance to Australia. Intended to augment the list of wetlands of international importance under the Ramsar Convention, it was formerly published in report form, but is now essentially an online publication...

.

Description

The system comprises Tarrabool Lake
Tarrabool Lake
Tarrabool Lake is located on the western fringe of the Barkly Tableland in northeastern Northern Territory, Australia. The size of the lake fluctuates as a function of the amount of precipitation that the surrounding area receives in any given year...

 and a swamp to its north-west on the Eva Downs pastoral lease
Pastoral lease
A pastoral lease is Crown land that government allows to be leased, generally for the purposes of farming.-Australia:Pastoral leases exist in both Australian commonwealth law and state jurisdictions....

. In wetter years, the two water bodies merge to form a single freshwater wetland of up to 2750 km2. Tarrabool Lake and Eva Downs Swamp are usually inundated seasonally and may retain water for a year or more after major flood events.

Vegetation

Tarrabool Lake is dominated by low, open Coolibah
Eucalyptus coolabah
Eucalyptus coolabah is a eucalypt of riparian zones and is found throughout Australia from arid inland to coastal regions. The plant is commonly called coolibah or coolabah, the name being a loanword from the Indigenous Australian Yuwaaliyaay word, gulabaa.Propagation is dependent on periods of...

 woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...

, with Lignum
Muehlenbeckia florulenta
Muehlenbeckia florulenta, commonly known as Tangled Lignum or often simply Lignum, is a plant native to inland Australia. It is associated with wetland habitats, especially those in arid and semiarid regions subject to cycles of intermittent flooding and drying out...

 shrubland
Shrubland
Shrubland, scrubland, scrub or brush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity...

, patches of open Northern Bluebush
Maireana
Maireana is a genus of around 57 species of perennial shrubs and herbs in the family Amaranthaceae which are endemic to Australia. Species in this genus were formerly classified within the genus Kochia...

 shrubland, and with extensive areas devoid of trees. The centre of Eva Downs Swamp is dominated by open Belalie
Acacia stenophylla
Acacia stenophylla is a fast-growing tree that grows 4-10m tall. It is native to Australia and is widely planted in landscapes in the Southwest USA. It is not listed as a threatened species. It has medium salt and frost tolerance. The average minimum annual rainfall that the tree needs is around...

 woodland in association with Lignum shrubland, and is surrounded by Northern Bluebush shrubland, with tall tussock grassland
Tussock grassland
Tussock grassland is a form of open grassland common in many temperate southern hemisphere regions, notably in New Zealand, but also in Australia, Argentina, some subantarctic islands, and parts of southern and eastern Africa....

 to the south-east, and Coolibah woodland in the south. Drying or marshy areas of the system have prolific swathes of groundcover
Groundcover
Groundcover refers to any plant that grows over an area of ground, used to provide protection from erosion and drought, and to improve its aesthetic appearance .- Ecosystem :...

 plants such as Schoenoplectus dissachanthus. Nardoo
Marsilea
Marsilea is a genus of approximately 65 species of aquatic ferns of the family Marsileaceae.These small plants are of unusual appearance and do not resemble common ferns...

 is common.

Birds

The core of the wetland system has been identified as an 1186 km2 Important Bird Area
Important Bird Area
An Important Bird Area is an area recognized as being globally important habitat for the conservation of bird populations. Currently there are about 10,000 IBAs worldwide. The program was developed and sites are identified by BirdLife International...

 (IBA) by BirdLife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...

 because it supports over 200,000 waterbirds when extensively flooded. It has periodically supported over 1% of the world populations of Australian Pelican
Australian Pelican
The Australian Pelican is a large water bird, widespread on the inland and coastal waters of Australia and New Guinea, also in Fiji, parts of Indonesia and as a vagrant to New Zealand.-Taxonomy:...

s and Straw-necked Ibis
Straw-necked Ibis
The Straw-necked Ibis is a bird of the ibis and spoonbill family Threskiornithidae. It can be found throughout Australia, New Guinea, and parts of Indonesia. Adults have distinctive straw-like feathers on their neck....

es, their breeding colonies being among the largest recorded in the Australian tropics. Other birds which have bred in the IBA in relatively large numbers include Freckled Duck
Freckled Duck
The Freckled Duck is a moderately large, broad-bodied duck native to southern Australia. The duck is protected by law...

s, Great
Great Egret
The Great Egret , also known as the Great White Egret or Common Egret, White Heron, or Great White Heron, is a large, widely-distributed egret. Distributed across most of the tropical and warmer temperate regions of the world, in southern Europe it is rather localized...

 and Intermediate Egret
Intermediate Egret
The Intermediate Egret, Median Egret, or Yellow-billed Egret is a medium-sized heron. It is a resident breeder from east Africa across tropical southern Asia to Australia. It often nests in colonies with other herons, usually on platforms of sticks in trees or shrubs...

s, Glossy Ibis
Glossy Ibis
The Glossy Ibis is a wading bird in the ibis family Threskiornithidae.This is the most widespread ibis species, breeding in scattered sites in warm regions of Europe, Asia, Africa, Australia, and the Atlantic and Caribbean region of the Americas...

es, Gull-billed Tern
Gull-billed Tern
The Gull-billed Tern formerly Sterna nilotica , is a seabird of the tern family Sternidae...

s, Magpie Geese, Plumed Whistling-Ducks, Grey Teal
Grey Teal
The Grey Teal, Anas gracilis is a dabbling duck found in open wetlands in New Guinea, Australia, New Zealand, Vanuatu and Solomon Islands....

s and Hardhead
Hardhead
The Hardhead, Aythya australis, is the only true diving duck found in Australia. Hardheads are common in the south-east of Australia, particularly in the Murray-Darling Basin, but also in the wetter country near the coasts. They are moderately nomadic in normal years, but disperse widely in times...

s. Nationally vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

 Australian Painted Snipe
Australian Painted Snipe
The Australian Painted Snipe is a medium-sized, long-billed, distinctively patterned wader.-Taxonomy:The distinctiveness of the Australian Painted-snipe was recognised by John Gould in 1838 when he described and named it Rostratula australis. However, it was subsequently lumped with the Greater...

s bred at Tarrabool in 1993.
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