NT
Black Grasswren Amytornis housei



Justification

Justification of Red List Category
This species has been uplisted to Near Threatened because large scale anthropogenic fires are thought to have reduced the area it occupies to levels approaching the thresholds for Vulnerable, it occurs at a moderately small number of locations and is inferred to be undergoing declines in range, population, habitat quality and number of locations.

Population justification
The global population size has not been quantified, but the species may be locally quite common (Flegg and Madge 1995, Higgins et al. 2001).

Trend justification
A continuing decline is inferred from recent and likely ongoing fire regimes (Garnett et al. 2011), however the rate of decline has not been quantified.

Distribution and population

This species is found in the Kimberley region of northern Western Australia, Australia, from Admiralty Gulf south through the Mitchell Plateau, Roe, Prince Regent, Glenelg and upper Charnley rivers, to Manning Creek. Much of its range occurs in Aboriginal reserves, vacant crown land or conservation reserves including the Prince Regent River Reserve which covers c.6,340 km2. This species was once considered scarce, but this was primarily because few ornithologists visited its remote, largely inaccessible habitat. It has since been reported to be moderately common to common e.g. 16 pairs counted in a 2 km transect along a creek in sandstone near Mertens Falls (Johnstone and Storr 2004), with a total population of 15,000 mature individuals postulated (Garnett et al. 2011). It may have been extirpated from Manning Creek by fire, and an increase in large scale anthropogenic fires late in the dry season is inferred to be driving a decline in the range and population.

Ecology

The species is found in hummock grassland habitat, being moderately common in dense porcupine-grass Triodia spp. in low open woodland, tall shrubland or tall open shrubland (Garnett et al. 2011). It is mainly found in dissected sandstone areas with massive boulders (Rowley and Russell 1997, Johnstone and Storr 2004), and feeds on insects, other invertebrates and seeds of grasses and sedges (Johnstone and Storr 2004).

Threats

The primary threat is the increased extent and frequency of fire, with the likely impact of current fire regimes being negative on habitat quality and reproductive success (Woinarski and Legge 2013). Fire frequency may have increased partly because of an increase in rainfall over the last 100 years that is accelerating recovery of the spinifex following fire and increasing fuel loads. There have also been changes in how people in the region use and manage fire. From 1990–1999, an average of 31% of the North Kimberley region was burned each year, mostly in hot dry-season burns (Fisher et al. 2003, in Garnett et al. 2011). However, parts of its range are naturally protected by the extremely rugged terrain that breaks up fire and protects the old spinifex. The ecologically similar Carpentarian Grasswren A. dorotheae may not re-occupy areas until at least three years after a fire (Harrington et al. 2009). Grasswrens are relatively poor dispersers and recolonisation is dependent on a nearby source population and hence dependent on the size, intensity and pattern of recent fires.

Conservation actions

Conservation Actions Underway
None are known.

Conservation Actions Proposed
Initiate regular monitoring at a selection of known sites. Study the effect of fire by investigating relationship between fire histories in occupied and unoccupied habitat patches. Maintain and enhance habitat suitability through fire management (Garnett et al. 2011).

Acknowledgements

Text account compilers
Butchart, S., Ekstrom, J., Fisher, S., Harding, M., Symes, A., North, A.

Contributors
Watson, C.


Recommended citation
BirdLife International (2021) Species factsheet: Amytornis housei. Downloaded from http://www.birdlife.org on 27/11/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/11/2021.