The vast majority (>99%) of records of Plains-wanderers in NSW over the past 30 years come from an area of the western Riverina bounded by Hay and Narrandera on the Murrumbidgee River in the north, the Cobb Highway in the west, the Billabong Creek in the south, and Urana in the east (Baker-Gabb 1990a, Maher 1997). Even within its western Riverina stronghold, the Plains-wanderer has a very patchy distribution. Surveys in the 1990s across 5,000km2 of the western Riverina covering 37 properties found only 5% of the total area comprised suitable habitat. The amount of high quality habitat in the Riverina drops to 1-2% during very wet or dry years when grasslands become too dense or are grazed too bare for Plains-wanderers (Maher 1997).
An Aerial Photo Interpretation (API) mapping project conducted by the former NSW NPWS confirmed the patchy distribution of the Plains-wanderer's habitat (Roberts and Roberts 2001). This API mapping project covered 2.28 million hectares or nine 1:100, 000 map sheets. Approximately 2.3% of the mapping area was identified as primary habitat suitable for Plains-wanderers all year round. A further 4.3% of the 2.28 million ha is comprised of denser, secondary habitat that may be periodically occupied by Plains-wanderers, particularly during drought or extended periods of heavy grazing when primary habitat can become too sparse for the Plains-wanderer. No populations or individual Plains-wanderers occur in NSW as the result of translocations.
The Plains-wanderer has declined greatly since European settlement. Areas where the species was formerly common and is now so reduced in numbers that it is effectively extinct include eastern NSW, south-western Victoria, and south-eastern South Australia. Its current stronghold is the western Riverina of southern NSW. Areas of secondary importance include north-central Victoria and central-western Queensland (Baker-Gabb 1998). The bird was formerly fairly common until about 1920 on the Slopes and Tablelands, and there are two earlier records of birds near Sydney. The main reason for the decline in the numbers and distribution of Plains-wanderers in all eastern States has been the conversion of native grasslands to dense introduced pasture or croplands (Bennett 1983). If native grasslands are not overgrazed or cultivated then Plains-wanderers are largely sedentary (Baker-Gabb et al. 1990), though there is some recent evidence to suggest that birds may not remain sedentary during prolonged drought conditions (DECC unpubl.).
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