The vertebrate fauna of Australian MTEs shows no unusual level of high diversity of endemism. The majority of the fauna in these MTEs are populations of more typically arid or mesic habitat species whose ranges extend into Southwestern or South Australia. Thus, the majority of the vertebrates appear to have relatively broad ecological niches rather than specialized requirements unique to the MTEs.
For mammals, the mediterranean-climate fauna includes only 57 species, 12 of these being endemic. Interpreting the patterns of distribution of large mammals is made difficult, however, by the strong impact that both Aboriginal and European populations have had on this fauna. The extinction of a large megafauna in the late Quaternary left the Australian continent without large grazers or predators.
Bird diversity is also relatively low, with 285 species regularly present. Ten of these are endemic. Most notable among these endemics is the black swan (Cygnus atratus), shown on the state emblem for Western Australia. Diversity is high among reptiles in southwestern Australia, an evolutionary consequence in part of the low mammal diversity. There are 177 native species, with 27 of these being endemic. Amphibians include 33 native species, with 19 endemic species and four endemic genera.
With only small areas of riverine or freshwater habitat, fish diversity in Southwestern Australia is low. Only 20 native species are present but half of these are endemic. These include three endemic genera and one