Thick-billed Grasswren (north-west NSW subspecies) - profile

Indicative distribution

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Key:

known

predicted

The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.

Scientific name: Amytornis modestus obscurior

Conservation status in NSW: Critically Endangered

Commonwealth status: Critically Endangered

Gazetted date: 31 Jul 2009

Profile last updated: 14 Oct 2024

Description

The Thick-billed Grasswren is a thick-set, finely streaked, pale fawn grasswren with a heavy bill. It can be told apart from other grasswrens by a combination of the stout bill and drab uniform brownish plumage with coarsely white-streaked head and upperparts and faintly streaked underparts.

Distribution

Generally thought to be extinct in NSW until located in the White Cliffs -Packsaddle area in 2008. May still occur at other locations in Upper Western Region.

Habitat and ecology

Mobile within a local region, usually inhabiting dense, low saltbush, cottonbush, bluebush and nitre-bush areas on sandy plains or depressions in gibber; also occurs along watercourses in clumps of Canegrass; when disturbed, individuals take refuge in any available cover, including piles of old flood debris along dry sandy watercourses and down rabbit burrows.
In NSW, preferred habitat appears to be shrubland dominated by Blackbush (Maireana pyramidata) that is higher and denser than surrounding areas.
The nest is deep and loosely-made, shaped either like a cup, half-dome or dome; located on or near the ground in a clump of Canegrass, within the foliage of low shrub (saltbush, bluebush) or in flood debris, and constructed of dead grasses, twigs and dry bark strips.
Established pairs maintain 20 - 40 hectare territories year-round and rarely, perhaps never, band with their neighbours outside the breeding season. In NSW nesting has been recorded in April, however studies in SA indicate grasswrens are known to breed opportunistically after rainfall events and thus could occur throughout the year.
Forages on the ground and under or around bushes for a wide variety of seeds, berries and invertebrates.
When disturbed, birds often run along the ground between shrubs rather than fly and sometimes perch on top of shrubs to look for danger.

Regional distribution and habitat

Click on a region below to view detailed distribution, habitat and vegetation information.

Threats

Overgrazing by sheep is thought to have caused soil erosion and reduced chenopod recruitment.
Clearing of vegetation eliminates habitat for this species.
Predation by foxes and feral cats is likely to occur, but its impact on the species is unknown.
Uncertainty as to the full distribution of the species population and its habitat.
Lack of knowledge of basic ecology, habitat requirements, common predators and breeding patterns.
Feral goats have potential to degrade habitat and in conjunction with rabbits, prevent chenopod shrub regeneration.This effect can be permanent where overgrazing has caused soil erosion, reducing chenopod recruitment even when grazing pressures are relieved.
Changes to rainfall seasonality, frequency and / or intensity may alter habitat composition in the long-term to the detriment of the species usage ability, particularly in combination with heavy grazing.
Soil erosion causes a loss of chenopod scrubland habitat.
Disturbance of habitat from mineral exploration and the possibility of a mine site development in future will impact on the species viability in the locality due to its small population size.
Lack of knowledge of the species demographic parameters and habitat use precludes targeted management actions to reduce threats.
Lack of knowledge of the species demographic parameters and habitat use in relation to bird species that are similar in range and habitat but that are not threatened (e.g. some fairy-wren species). Do these other species adapt better and are therefore competition for grasswrens?

Recovery strategies

A targeted strategy for managing this species has been developed under the Saving Our Species program; click here for details. For more information on the Saving Our Species program click here

Activities to assist this species

Control vertebrate pest populations (e.g. foxes, cats and rabbits), that either prey on, or compete against this species for resources.
Reduce stock intensity of, or exclude grazing in, some areas to allow regeneration of vegetation for habitat, such as food sources or nest sites.
Restrict cultivation around suitable ground habitat.
Retain understorey shrubs and allow them to complete their life cycle (i.e., seed set, germination, establishment, growth to maturity).
Prevent clearing of habitat, such as nesting sites and food sources.

Information sources

Black, A and Gower, P (2017) Thick-Billed Grasswren. Pp 49-56 in Grasswrens : Australian Outback Identities, Axiom publishing.
Black, A. (2011) Subspecies of the Thick-billed Grasswren Amytornis modestus (Aves-Maluridae). Transactions of the Royal Society of South Australia 135(1): 26-38
Black, A.B., Joseph, L., Pedler, L.P. and Carpenter, G.A. (2011) A taxonomic framework for interpreting evolution within the Amytornis textilis–modestus complex of grasswrens. Emu 110(4): 358-363
Garnett, S.T., Szabo, J.K. and Dutson, G. (2011) Action Plan for Australian Birds 2010. (CSIRO Publishing, Collingwood, Victoria)
Higgins, P.J., Peter, J.M. and Steele, W.K. (eds) (2001) Handbook of Australian, New Zealand and Antarctic Birds. Volume 5: Tyrant-flycatchers to Chats. (Oxford University Press, Melbourne)
NSW National Parks and Wildlife Service (2002) Thick-billed Grasswren (eastern subspecies) (Amytornis textilis modestus) (North, 1902) Recovery Plan. (NSW NPWS, Hurstville)
NSW Scientific Committee (2008) Thick-billed Grasswren Amytornis textilis - Review of Current Information in NSW.
NSW Scientific Committee (2009) Thick-billed Grasswren (eastern subspecies) Amytornis textilis modestus - critically endangered species - Final Determination.
Parker, D.G., Egan, D. and Ballestrin, M.L. (2010) Recent Observations of the Thick-billed Grasswren Amytornis textilis modestus in New South Wales. Australian Field Ornithology 27(4): 159-164

IBRA Bioregion	IBRA Subregion	Known or predicted	Geographic restrictions region

Broken Hill Complex	Barrier Range	Predicted	None
Broken Hill Complex	Barrier Range Outwash	Predicted	None
Broken Hill Complex	Mootwingee Downs	Known	None
Channel Country	Central Depression	Predicted	None
Channel Country	Sturt Stony Desert	Predicted	None
Mulga Lands	White Cliffs Plateau	Known	None

Sounds

Images

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