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Scientific Name: Botaurus poiciloptilus
Conservation Status: Endangered
Body Length: 66–76 cm
Distribution: Isolated population in south-western Australia as well as near-coastal northern and eastern Australia
Habitat: Freshwater wetlands
Distinguishing feature: ‘Bunyip-like’ call
With a booming call and mysterious behaviour, the Australasian Bittern (Botaurus poiciloptilus) is a truly unique and characteristic waterbird species of the Blackwood Catchment.
This bird is listed internationally as an endangered species on the 2004 IUCN Red List of Threatened Species, nationally as an endangered species under the Environment Protection and Biodiversity Conservation Act 1999 and within Western Australia as rare under the Wildlife Conservation Act 1950 (Robyn Pickering Australasian Bittern Co-ordinator WA, pers. comm., EPBC Act, DSEWPC 2012).
In Australia the species’ range includes large wetland environments in southwest Australia, southern Queensland to Tasmania and the southeast of South Australia. In Australia numbers of the Australasian Bittern have declined dramatically (up to 51%) over the last 40 years (Peter 2009).
Within Western Australia the distribution of the Australasian Bittern has contracted during the 1900s to south western areas from Perth to Albany and around Esperance. Declines in numbers have been associated with loss of habitat attributed to lower water levels, increases in salinities and/or prolonged inundation as a result of both degradation and seasonal variation, with current WA population estimates of around 150 adult birds. (Jaensch et al 2009, Robyn Pickering Australasian Bittern Co-ordinator WA, pers. comm.)
Major threats to the species are:
- Climate change
- Acid sulphate soils and acid flush following rewetting
- Degradation to wetlands from adjacent land management (agriculture)
- Predation by invasive animals – fox, cat, rat, pig
- Decreasing water levels due to draw down by tree plantations and/or decreased rainfall
- Inappropriate fire regimes – drying climate & hydrology; infrequent burning; too frequent burning
- Predation by native animals – Swamp Harrier, native rats, snakes
Australasian Bittern distribution map (source: Birdlife WA)