Southwest Australia
The region covers 356,717 km2, consisting of a broad coastal plain 20–120 kilometres wide, transitioning to gently undulating uplands made up of weathered granite, gneiss and laterite.
In the summer months, the lower-latitude anticyclonic belt, with generally dry easterly winds, moves southwards, increasing temperatures and decreasing rainfall.
Summertime maximum temperatures have increased by 0.1º to 0.3º C per decade, and the average number of days per year over 40º C in Perth has doubled over the last century.
[6] Lower rainfall and higher temperatures have reduced stream flow and inflow into drinking water and irrigation catchments since the 1960s.
The region has generally nutrient-poor sandy or lateritic soils, which has encouraged rich speciation of plants adapted to specific ecological niches.
Other mammals endemic to Southwest Australia are the western brush wallaby (Macropus irma) and the quokka (Setonix brachyurus).
[citation needed] Southwest Australia is an Endemic Bird Area, with several endemic species of birds including the long-billed black cockatoo (Zanda baudinii), western corella (Cacatua pastinator), noisy scrubbird (Atrichornis clamosus), red-winged fairywren (Malurus elegans), western bristlebird (Dasyornis longirostris), black-throated whipbird (Psophodes nigrogularis), white-breasted robin (Eopsaltria georgianus), and red-eared firetail (Stagonopleura oculata).
The perennial streams extend from east of Esperance on the south coast to the Arrowsmith River north of Perth, most often in areas with 700 mm or more of annual rainfall.
As with its terrestrial flora, Southwest Australia's Mediterranean climate and biogeographic isolation has given rise to a distinct freshwater ecoregion with many endemic species.
The first evidence of human habitation of the region was 50,000 years ago at Devil's Lair by ancestors of today's Aboriginal people.
Frequent burning reduced tree cover and encouraged the growth of grasses, herbs, and low shrubs, fostering open woodlands and savannas and limiting areas of dense forest and thicket.
European settlers mostly dispossessed the Aboriginal inhabitants, and established extensive agriculture, including wheat, barley, canola, lupins, and oats.
