Plains-wanderer, Pedionomus torquatus, is endemic to Australia, recorded from north-central Victoria, north-eastern South Australia, southern New South Wales around the Riverina, and west-central Queensland (Barrett et al. 2003, Commonwealth of Australia 2016). It is currently listed as Endangered under criterion C2a(ii) on the basis that is has a very small population which is undergoing a continuing decline as a result of habitat loss and degradation (BirdLife International 2017). However, this species was recently reviewed by the Australian Threatened Species Scientific Committee (TSSC) and uplisted to Critically Endangered in Australia (TSSC 2015).
The species inhabits sparse grasslands with c.50% bare ground, with most vegetation 5-15cm in height with some widely spaced plants up to 30 cm high (Baker-Gabb et al. 1990, Baker-Gabb et al. 2016). It may remain in an area for as long as the habitat remains suitable, and will occasionally use lower-quality habitat including cereal stubble, but cannot persist in a cropped landscape (Garnett et al. 2011). The cultivation of native grassland has virtually extirpated the species from southern South Australia and Victoria, and cultivation is increasing across the New South Wales Riverina (Garnett et al. 2011). Where suitable patches of habitat survive, they are often too few and dispersed to be suitable for this species. Grazing can also affect this species, with too much or too little leading to desertion of an area by the species. Too much grazing may lead to the species being more vulnerable to predators (Baker-Gabb et al.1990), while too little after rainfall and rapid grass-growth will mean that it the habitat is too dense for the species (Baker-Gabb et al. 2016). A range of other threats may impact upon this species, the most serious of which may be climatic events such as drought and flood, which will impact upon habitat management, and so make it harder to appropriately manage areas for this species (TSSC 2015).
Garnett et al. (2011) estimated the total number of mature individuals to be c.2,000 and decreasing. Since then, significant declines in Plains-wanderer numbers have been reported in Victoria and New South Wales, and the population size has more recently been estimated at <1,000 mature individuals (TSSC 2015). Monitoring and annual surveys conducted across the Northern Plains of Victoria between 2010 and 2015 indicated a decline in numbers of > 90% during this period (Baker-Gabb et al. 2016), while monitoring across the New South Wales Riverina (which held the highest densities of this species [Garnett et al. 2011]) detected a decline of 93% across the region over the period from 2001 to 2014 (Wilson et al. 2014). The generation length for this species is c. 7 years, and so declines over 3 generations could be even greater than those presented. On the other hand, as the species will move away from unsuitable areas, part of these declines could represent the species moving to new, as yet unfound, sites. However, in the absence of any evidence for this species moving to new areas, the rate of decline in this species may be conservatively considered to be >80% over the past 3 generations. Hence the species warrants listing as Critically Endangered under criterion A2ac.
We welcome any comments and further information regarding this proposed uplisting.
Baker-Gabb D. J.; Benshemesh J. S.; Maher P. N. 1990. A revision of the distribution, status and management of the Plains-wanderer Pedionomus torquatus. Emu 90: 161-168.
Baker-Gabb, D.; Antos, M.; Brown G. 2016. Recent decline of the critically endangered Plains-wanderer (Pedionomus torquatus), and the application of a simple method for assessing its cause: changes in grassland structure. Ecological Management and Restoration.
Barrett, G.; Silcocks, A.; Barry, S.; Cunningham, R.; Poulter, R. 2003. The new atlas of Australian birds. Royal Australasian Ornithologists Union, Victoria, Australia.
BirdLife International. 2017. Species factsheet: Pedionomus torquatus. Downloaded from http://www.birdlife.org on 14/03/2017.
Commonwealth of Australia. 2016. National recovery plan for the Plains-wanderer Pedionomus torquatus. Commonwealth of Australia, Canberra.
Garnett, S. T.; Szabo, J. K.; Dutson, G. 2011. The Action Plan for Australian Birds 2010. CSIRO Publishing, Collingwood.
TSSC. 2015. Approved conservation advice for Pedionomus torquatus (Plains-wanderer). Threatened Species Scientific Committee, Commonwealth of Australia, Canberra.
Wilson, C.; Ingwersen D.; Parker D. 2014. Review of OEH Plains-wanderer Pedionomus torquatus monitoring data 2001-2014. A report for the Office of Environment and Heritage, NSW. BirdLife Australia, Melbourne.