Data Zone
Justification of Red List category
This species has undergone recent rapid population declines as a result of fires in 2011-2012 that are thought to have severely reduced the population by 30-50% in the past ten years. As a result it is classified as Vulnerable.
Population justification
The population of Carpentarian Grasswrens is estimated at 2,600–14,000 individuals based on a density estimate of two mature birds per 2 km2 breeding territory. The number of breeding territories comes from the combined area of 'probable habitat', as defined by a habitat suitability model (H Stoetzel unpublished), within convex hulls measured independently for each subpopulation. However, these estimates are based on limited search effort, particularly in the north of the species' range where the extent of occurrence boundary is uncertain.
Trend justification
Major fires in 2011 and 2012 reduced the AOO and are thought to have caused the population to decline by >30%–50% within the last ten years. The decline in the area occupied is thought to be reflected in a decline in population. Between 2008 and 2013, the species' extent of occurrence was estimated to have declined by around 33%, and its area of occupancy by around 35%, with the bulk of these declines being attributed to the severe fires in 2011 and 2012 (Harrington & Murphy 2015). Though these fires eliminated grasswrens from large areas which have not yet been recolonised, such widespread fire events have not occurred since. A longer-term trend of increasing fire extent (Russell-Smith 2001) is likely to have been affecting the population since the removal of Aboriginal land management, justifying the species to be retrospectively assessed as Near Threatened in 2000 and 2010.
Carpentarian Grasswrens occur in three subpopulations: in the Northern Territory on Wollogorang Station, and in Queensland on Boodjamulla National Park, and around Buckley River near Mount Isa (Harrington and Murphy 2015). They previously occurred near Borroloola in the Northern Territory (McKean and Martin 1989), but this population appears to have been extirpated (Harrington and Murphy 2015).
Carpentarian Grasswrens inhabit fire-prone Triodia dominated tropical savanna, foraging for insects and seeds on the ground amongst shrubs and Triodia hummocks. In the north, the species is associated with rugged sandstone outcrops that offer protection from some fires; in the south, it probably persists in low, undulating terrain only if fire frequency is low (Perry et al. 2011). Breeding appears to coincide with monsoonal rainfall events, building a dome-shaped nest in the upper portion of a Triodia hummock (Higgins et al. 2001). Burnt habitat can be recolonised 3–4 years post-fire depending on the rainfall and the proximity of a source population (Murphy et al. 2011): dispersal across unsuitable habitat, particularly across the recently burnt area, is thought to be limited (Murphy et al. 2011).
Severe, extensive fires are considered the primary threat to Carpentarian Grasswrens (Harrington and Murphy 2015), which is exacerbated by a lack of mosaic burning, changes in rainfall patterns and the spread of naturalised vegetation, particularly buffel grass Cenchrus ciliaris (Garnett et al. 2011; Grice et al. 2013; Harrington and Murphy 2015; Crowley 2016). Other potential threats include localised impacts of mining and associated development and predation by cats Felis catus (TSSC 2016). Much of the species' habitat is on pastoral properties, but the impacts of large-scale grazing are unknown; Triodia is generally not heavily grazed by cattle.
Conservation and Research Actions Underway
Some of the population occurs within a protected area. Listed as threatened under appropriate legislation. Community engagement through fire management and species monitoring. Traditional multi-aged burning regimes in the late wet/early dry season being re-established on two pastoral properties (Calton Hills and Thorntonia), and Boodjamulla National Park. Persistence is being monitored throughout the species' range.
Conservation and Research Actions Proposed
Continue monitoring at a selection of known sites. Determine distributional limits and how they are determined. Understand dispersal ability following fire, minimum patch size and post-fire ages required for persistence. Monitor fire patterns from satellite imagery and model impact on habitat. Improve understanding of the impacts of threats and how to manage them. Determine the effect of Cenchrus ciliaris invasion on habitat occupancy and fire patterns. Assess the extent of genetic variation between subpopulations and time since separation. Investigate consequences of co-occurrence with the Kalkadoon Grasswren A. ballarae. Develop and encourage the adoption of fire management that favours the species, creating a mosaic of spinifex ages by burning <10% of the total area each year, burning any site at intervals of >10 years, each fire <20 km2 and mostly late or very early in the wet season (Garnett et al. 2011). Involve private landowners in fire management (Harrington and Murphy 2013). Reduce the spread of buffel grass. Reduce the size of feral cat population as required.
16-17.5 cm medium-sized grasswren. Male with blackish head grading to rufous on back. Lower back to uppertail-coverts unstreaked rich rufous. Upperwing and tail dusky brown with rufous edging. Breast and upper belly white. Lower belly and flanks tawny. Strong black malar stripe. Female resembles male except flanks and lower belly are deep chestnut (Rowley et al. 2007). Similar spp. Smaller, slimmer and more rufous plumage than White-throated Grasswren A. woodwardi. Voice Long, sweet-sounding song. Contact calls high-pitched cricket-like chirps (Rowley et al. 2007).
Text account compilers
Vine, J., North, A., Garnett, S., Taylor, J., Symes, A., Calvert, R., Ashpole, J, Stattersfield, A.
Contributors
Fox, I., Woinarski, J.C.Z. & Watson, C.
Recommended citation
BirdLife International (2024) Species factsheet: Carpentarian Grasswren Amytornis dorotheae. Downloaded from
https://datazone.birdlife.org/species/factsheet/carpentarian-grasswren-amytornis-dorotheae on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.