Data Zone
Justification of Red List category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence under 20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size may be small, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (under 10,000 mature individuals with a continuing decline estimated to be over 10% in ten years or three generations, or with a specified population structure). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (over 30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.
Population justification
The population is estimated at under 100,000 individuals (S. Garnett in litt. 2003). Population loss in southern Australia occurred prior to the past three generation (35 years) period, and the population in the north of the country is now relatively stable. Trends in Indonesian and Papua New Guinea are unknown but birds here account for only a fraction of the global population, but combined with local declines in some parts of Australia due to invasive non-native mammals, pesticide use and hunting (Garnett and Crowley 2000, Ziembicki and Woinarski 2007, Collar and Garcia 2020), the species' population size is suspected to be slowly declining.
Trend justification
Population loss in southern Australia occurred prior to the past three generation (47 year) period, and the population in the north of the country is now relatively stable. Trends in Indonesian and Papua New Guinea are unknown but birds here account for only a fraction of the global population. The overall population trend is therefore suspected to be stable.
Ardeotis australis occurs across continental Australia and occasionally in southern Papua New Guinea and Papua (formerly Irian Jaya), Indonesia. The total population is thought number less than 100,000 birds (S. Garnett in litt. 2003), and almost certainly more than 10,000 mature individuals (Garnett et al. 2011), with the majority occurring in northern Australia. It is rarely recorded on the plains of south-western Papua New Guinea. It has all but disappeared from south-eastern Australia, and is less abundant elsewhere, particularly south of the tropics. Local population size varies strongly with rainfall (Ziembicki and Woinarski 2007) making assessment of trends difficult, however population loss in southern Australia is believed to have been largely historical, and the population in the north is thought to be relatively stable. Satellite-tracking has provided substantial information on dispersal in this species, suggesting that populations in higher-rainfall northern Australia undergo relatively local dispersal, whereas those in lower-rainfall areas may undergo far more substantial regional and inter-regional movements (J. Woinarski in litt. 2007). In southern and central Queensland, this species appears to move eastwards in autumn, retracting westwards later in the year (J. Woinarski in litt. 2007).
It inhabits grassland, including tussock grassland, Triodia hummock grassland, grassy woodland, low shrublands, and structurally similar artificial habitats, such as croplands and golf-courses. It will also use denser vegetation, when this has been temporarily opened up by recent burning. It lays one, or occasionally two, eggs on the ground, where possible along a boundary between open grasslands and more protective shrubland or woodlands (Marchant and Higgins 1993). In northern Australia it may disperse widely to follow recently-burnt grounds (J. Woinarski in litt. 2007).
Its widespread historical decline was probably caused by a combination of intensive agriculture, invasion of pastoral land by woody weeds, hunting, changes to fire regimes and predation by the Red Fox Vulpes vulpes (Harrington et al. 1984, Marchant and Higgins 1993, J. Woinarski in litt. 2007). It readily deserts nests in response to disturbance by humans, sheep or cattle (Marchant and Higgins 1993). Pesticides, either directly or indirectly ingested, are also held responsible for local extinctions (Ziembicki and Woinarski 2007). The area where it has declined corresponds with the distribution of foxes in Australia, a distribution that may be slowly expanding northwards. Traditional and illegal hunting by people is also considerable and may be contributing to the perceived decline in northern and central Australia (Garnett and Crowley 2000). Across northern Australia it may be less common in areas invaded by woody weeds. Local increases in abundance have occurred in parts of northern Australia in response to recent clearing (Garnett and Crowley 2000) and subsequent horticultural development, but this effect may dissipate as agriculture intensifies (J. Woinarski in litt. 2007).
Conservation Actions Underway
Studies have taken place which examine the ecology and movements of this species in northern Australia (J. Woinarski in litt. 2007). This research provided estimates of its population density at several sites, and established reliable and robust methodologies for estimating abundance (J. Woinarski in litt. 2007). Non-traditional hunting is banned in all Australian states and territories.
Text account compilers
Rutherford, C.A.
Contributors
Bishop, K.D., Garnett, S., Mathieson, M., Woinarski, J.C.Z. & Ziembicki, M.
Recommended citation
BirdLife International (2024) Species factsheet: Australian Bustard Ardeotis australis. Downloaded from
https://datazone.birdlife.org/species/factsheet/australian-bustard-ardeotis-australis on 22/11/2024.
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 22/11/2024.