Page:Cyclopedia of Western Australia, volume 1.pdf/51

State of Western Australia is only about one-third of the whole number of species. This fact is significant, as the conditions for animal existence in the west are essentially the same as in the eastern half of the continent. The rainfall map of Australia suggests at once the cause of this difference in animal life, for it is the food obtainable which governs the routes the occupying animals must travel in order to reach the areas in which they settle. The "fruit-eating" bats will keep to fruit-producing forests—unless man by planting orchards furnishes the desired source of supply—and such forests in Australia occur only within the rainfall zone of 30 in. and upwards. The large species of kangaroo keep to the great plains and grassy open scrubs, while the smaller species of this family, known as "wallabies," have their haunts amid brushwood or in rocky places. The insect-eating animals find their prey everywhere, especially the "ant-eaters." The Echidna and the Myrmecobius are the principal ant-eaters in the south, while small "pouched mice" and a blind mole (Notoryctus), which latter is found only in sandhill country, are also "ant-eaters." The rainfall zones of Western Australia naturally divide the State into four divisions, officially known as the north, north-west, central, and south-west, and the distribution of mammalian species within these divisions and along the sea-coast is strikingly brought out in the following tables. The first table summarizes the whole Australian and Tasmanian mammalia in genera and species, and the proportion of them contained within Western Australia; the second is a detailed list of the western species as distributed through the divisions mentioned.