Justification of Red List category
This species has a very small range, a restricted number of locations and a small population that is undergoing a continuing decline given the balance of fire frequency and the rate of population recovery from fire. As a result, the species is classified as Endangered.
Monitoring in the Waychinicup-Manypeaks to Two Peoples Bay area in 2019 resulted in the location of a total of 196 pairs (39% of the number estimated in 2001; Comer et al. 2020). The Fitzgerald River National Park subpopulation numbered c.125 pairs in 2005 (Burbidge et al. 2010), but there have been fires since (2007, 2019) in the areas they occupied at that time (McNee et al. 2021). Overall the population is estimated in the range of 500-700 mature individuals with a best estimate of 600 (Comer et al. 2021).
Fires have affected several populations in the last decade and birds appear to have been lost from some sites, e.g. Twertup Track in Fitzgerald River National Park (AH Burbidge unpublished). In 2014 there were estimated to be 363 pairs of Western Bristlebirds in two subpopulations: 203 pairs Two Peoples Bay-Bluff Creek and <150 pairs Fitzgerald River National Park (Department of Parks and Wildlife 2014). Fires in 2015 at Mount Gardner and Mt Manypeaks in 2015 and 2020 will have reduced the number, which also happened in 2005 and 2006, largely as a result of wildfire, when they declined from about 600 pairs to 200–325 (Comer & McNee 2001, Tiller et al. 2006). Monitoring in the Waychinicup-Manypeaks to Two Peoples Bay area in 2019 resulted in the location of a total of 196 pairs (39% of the number estimated in 2001; Comer et al. 2020). The Fitzgerald River National Park subpopulation numbered c.125 pairs in 2005 (Burbidge et al. 2010), but there have been fires since (2007, 2019) in the areas they occupied at that time (McNee et al. 2021). Thus, overall, the population is inferred to have declined over the last three generations.
Western Bristlebirds currently occur east of Albany, Western Australia, Australia, at Two Peoples Bay Nature Reserve, Betty's Beach, Mt Manypeaks to Bluff Creek, and at 14 different sites in and near Fitzgerald River National Park (Gilfillan et al. 2009). Historically they occurred around the coast from Perth to Augusta and from Albany to Fitzgerald River National Park, Western Australia (Cale and Burbidge 1993). Fires have affected several populations in the last decade and birds appear to have been lost from some sites, e.g. Twertup Track in Fitzgerald River National Park (AH Burbidge unpublished). Reintroductions to the former range near Walpole 1999–2007 have failed (Burbidge et al. 2010).
At Two Peoples Bay Nature Reserve, Western Bristlebirds live in dense closed heath up to 1.5 m high; near Waychinicup River and in the Fitzgerald River National Park, the heath only reaches 1 m high, sometimes with scattered patches of mallee eucalypts (McNee 1986). Territory size, estimated to be about 7 ha, can remain unchanged for at least 30 years (Smith 1987, A.H. Burbidge unpublished, in Comer et al. 2021) in the absence of fire, although in some areas the vegetation becomes too tall after about 20 years and the birds may leave. While subpopulations persist in almost all habitat patches that remain unburnt, and birds move to adjacent unoccupied habitat following some fires, severe fires can destroy all suitable habitat (Smith 1977, McNee 1986, Smith 1987) with moister areas usually remaining unoccupied for 2–3 years after fire (Burbidge 2003, TSSC 2018, Comer et al. 2021), drier areas for 11–14 years (Smith 1987). In the absence of older vegetation, bristlebirds occasionally move into areas burnt only months previously, but they probably do not breed in such younger vegetation. They build domed nests hidden low in heath in which two eggs are laid (Smith 1987).
Fire is the main current threat, with fires at intervals of less than 5–10 year leading to local extinction (Smith 1987) but the scale, frequency and intensity of fire has been increasing despite increased skills, capacity and effort to stop them. This trend is likely to continue as fire weather intensifies driven by longer, hotter droughts (Herold et al. 2018). Predation by foxes Vulpes vulpes and particularly cats Felis catus is a threat that is exacerbated by fire (Gilfillan et al. 2009; Burbidge et al. 2010). Vegetation dieback caused by Phytophthora cinnamomi, grazing by introduced animals, weed invasion and changes in hydrological regimes (Gilfillan et al. 2009) are considered plausible threats although their severity and impact are unknown.
Conservation Actions Underway
CITES Appendix I. Almost the entire range is within protected areas. Surveys have been completed over the range of the species, and populations are protected from fire as much as possible, particularly in association with the other threatened taxa of the Two Peoples Bay-Manypeaks area. In 1999-2000 and 2007, 18 birds were translocated to a site west of Albany, but the translocation appears to have been unsuccessful and there was no evidence of breeding (Garnett et al. 2011). Further translocations are planned (A. Burbidge in litt. 2007). The population in the Two Peoples Bay-Mt Manypeaks area is being monitored (Danks and Comer 2006, A. Burbidge in litt. 2007). The recovery of this species is being managed by the South Coast Threatened Birds Recovery Team (A. Burbidge in litt. 2007). There is active management of cats and fires.
17-20 cm. Medium-sized, sturdy, grey-brown passerine. Sexes similar. Dark brown upper back dappled pale grey. Dark brown lower back. Rich rufous-brown rump. Rufous-brown upperwing-coverts. Mostly rufous-brown uppertail. Off-white centre of breast and belly with fine black-brown scalloping, sparser on belly. Olive-brown sides of belly and flanks with fine black-brown scalloping. Mostly olive-brown undertail. Juvenile similar to adult, but upperparts without dappling. Similar spp. Noisy Scrub-bird Atrichornis clamosus differs by having barred upperparts and lacking scalloping on underparts. Voice Male, high chortling call, very variable within and between individuals. Female, replying with a sharp, usually three-noted whistle.
Text account compilers
Symes, A., Vine, J., Garnett, S., Berryman, A.
BirdLife International (2023) Species factsheet: Dasyornis longirostris. Downloaded from http://datazone.birdlife.org/species/factsheet/western-bristlebird-dasyornis-longirostris on 07/12/2023.
Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 07/12/2023.