Mammals of the tropical savannas

by John Woinarski

Bats make up around a third of the mammal species in the tropical savannas. This is the inland forest bat Photo: Alex Kutt

As with most other parts of Australia, native land mammals are not an obvious feature to the casual observer in northern Australia.

But the native mammal fauna is reasonably rich: it is just a bit discreet. Most mammals are small and nocturnal.

The main elements of the mammal fauna of northern Australia reflect that of the continent as a whole. About a third of the native fauna are bats (mostly small and insectivorous), about a fifth are rodents, and almost all the rest are marsupials — including kangaroos and wallabies, bandicoots, possums and dasyurids (quolls, dunnarts, phascogales and antechinuses). Most of the north has only one monotreme (the echidna). And, except for relatively small areas in north-eastern Queensland, the north lacks wombats, platypuses and koalas.

The mammal fauna varies gradually in composition from west (Kimberley) to east (Cape York Peninsula) and from the generally higher rainfall coastal areas to the inland. Particularly important areas, because of their concentrations of endemic mammal species, include the north Kimberley, the sandstone plateau of western Arnhem Land, and Cape York Peninsula.

Flying-foxes are a notable component of the native mammal fauna in northern Australia, because they often roost or forage in very large numbers (sometimes to the displeasure of some human residents). But they perform a very important ecological role, in pollination and seed dispersal. Dingoes remain common across large areas, although often in hybrid populations with feral dogs. Many macropod species are at least locally common and reasonably conspicuous: variably across different parts of the north these include the large antilopine wallaroo, euro (or common wallaroo), eastern grey kangaroo and red kangaroo, and the somewhat smaller agile wallaby.

Recently introduced mammals like this donkey are present in large numbers.

Northern Australia is important for the conservation of Australian mammals. Not only are there many endemic species, but the north has also retained some mammal species (or close relatives of species) that have been lost from the rest of the continent. These include the squirrel-sized tree-rats, the nailtail wallabies and the hare-wallabies.