VU
Kalkadoon Grasswren Amytornis ballarae



Justification

Justification of Red List Category
This species has a population size believed to contain fewer than 10,000 mature individuals all belonging to one subpopulation and with evidence of a continuing decline due to widespread wildfire. For these reasons, it is assessed as Vulnerable.

Population justification
Assuming breeding territories of an area of 2 km2 (Harrington et al. 2017), the population of A. ballarae is estimated at 220–11,000 mature individuals based on a density estimate of one mature individual per 1 km2. The upper limit of the population size is based on the area of good habitat within the EOO, the lower limit by the number of 2x2 km squares in which the species has been recorded since 1990, although some of these are no longer occupied (Stoetzel et al. 2021). The former value is considered to be more accurate since large areas of this species’ range have not been surveyed, although it is highly unlikely 100% of this area is occupied; the best estimate is consequently placed at 9,000-9,999 mature individuals.

Trend justification

All data from Stoetzel et al. (2021). In the north of the species’ range, where monitoring has been regular, the proportion of successful surveys has declined from 13%–32% in 2008–2009 to 3%–6% in 2017–2019, probably related to severe fires in 2011–2012 because the proportion of successful surveys in 2013 was 1.4%. Of the 38 monitored sites with birds present in 2008–2009, the species has been recorded at only 13 since 2013. Severe fires in 2011–2012 appears to have caused a 13% contraction in EOO from the north since 2008–2009. Although there have been few late-season fires since, extreme fire weather driven by longer and more severe droughts mean this species is projected to decline further in the future.


Distribution and population

Kalkadoon Grasswrens are endemic to the Selwyn Ranges of north-west Queensland, Australia. Their range is centred on Mt. Isa and extends to Dajarra in the south, near Camooweal in the west, Gigja in the north and Cloncurry in the east (Harrington et al. 2017). The species probably has poor dispersal capabilities and is unlikely to cross substantial distances of unsuitable habitat.

Ecology

Kalkadoon Grasswrens live in pairs or small parties (Carruthers et al. 1970) with good habitat consisting of mature spinifex Triodia spp. on or within 300 m of rocky sandstone and marble hills (Harrington et al. 2017). After fire, individuals returned to 30% of survey sites within 3- and 4-year-old fire scars, but occurred in 90% of survey sites where spinifex cover was ?10 years unburnt, and spinifex cover plateaued after six years (Harrington et al. 2017). They feed on small insects and seeds and have a clutch of two eggs laid in a cupped nest within spinifex (Higgins et al. 2001). Records of the species fall between 118 m and 551 m above sea level (GBIF.org 2022). 

Threats

The primary threat is widespread wildfire with lack of mosaic burning, altered rainfall patterns and the spread of naturalised grasses, particularly buffel grass Cenchrus ciliaris, all potentially contributing to an increased incidence of widespread wildfire (Grice et al. 2013, Crowley 2016). Mining and associated development, and predation by feral cats, are considered potential threats (Harrington et al. 2017).

Conservation actions

Conservation Actions Underway
Traditional multi-aged burning regimes in the late wet/early dry season are being re-established. Persistence is being monitored in the north of the species range.

Conservation Actions Proposed
Document trends in population and AOO. Understand of the impact of cats and buffel grass and how to manage them. Investigate consequences of co-occurrence with the Carpentarian Grasswren A. dorotheae. Reduce the scale of late-season fire throughout the species' range by implementing early-season planned burn programs. Mitigate the spread of buffel grass. Reduce the size of cat population as required.

Acknowledgements

Text account compilers
Vine, J.

Contributors
Symes, A.


Recommended citation
BirdLife International (2022) Species factsheet: Amytornis ballarae. Downloaded from http://www.birdlife.org on 06/10/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/10/2022.