The varied topography of what was to become the greater Melbourne metropolitan area provided habitat for a wide range of native mammals. Habitats ranged from grasslands on the volcanic plains in the west to lush, wet forest in the Dandenong Ranges. At the time of European settlement, some 25 to 30 species of terrestrial mammals and perhaps 16 or so species of bats were present. Some, like the Eastern Quoll are gone forever; others, such as the Common Brushtail Possum, are viewed by many Melburnians as pests. Most were hunted by local Aboriginal peoples for food and skins, and indeed the first Europeans were quick to capitalise on the abundant wildlife they found. A thriving market was soon established and the recollections of one of Melbourne's first game hunters - H.W. Wheelwright's Bush wanderings of a naturalist (1861) - provide a background for understanding the subsequent changes to the city's wildlife.
Most natural families of native mammals were found within Melbourne's boundaries. These were the egg-laying monotremes, platypus and echidna; carnivorous marsupials, the dasyures - antechinuses, dunnarts, quolls and Brush-tailed Phascogale; bandicoots; Common Wombat, and koala; possums; rat-kangaroos, and their more familiar cousins, kangaroos and wallabies; fruit-bats (or flying foxes) and many species of smaller insect-eating bats; native rats and mice; the dingo; and, in the waters of the bays, seals and dolphins, with larger whales occasional visitors. A diverse fauna, indeed, but one that has altered substantially since settlement.
Gone from 'suburban' Melbourne are the small carnivorous marsupials, although the Fat-tailed Dunnart may still hold on in the remaining grasslands in the north and west grasslands that are fast being converted to housing estates. Only in the Dandenongs can one still find the Agile and Dusky Antechinuses, mouse-sized insectivorous marsupials. Both quolls have vanished, but a wandering Spot-tailed Quoll somehow found its way into a chook-shed in Ringwood in 1983. At Warrandyte and Christmas Hills, small colonies of the threatened Brush-tailed Phascogale still occur. One species of bandicoot, the Southern Brown Bandicoot, which was very common in the south-eastern sand-belt, has fallen victim to progress and barely hangs on in parks and golf courses. Soon it will be gone like its relative, the Long-nosed Bandicoot. The nearest that species can be found is in the Dandenongs; even there it is often considered a pest, due to its habit of digging small holes in the soil in its search for earthworms and similar invertebrates.
The Yarra Valley (and the Dandenongs) still provide habitat for Common Wombats, in the less closely settled upper reaches near Warrandyte, and the koala has been reintroduced to the suburbs, expanding its range from the Warrandyte State Park into nearby areas and sometimes coming into conflict with motor cars, dogs and people. Koalas are often seen in the drier forests of the Dandenongs, for example, at Montrose. Possums are perhaps the most well known of the native mammals in Melbourne, particularly the Common Brushtail Possum and the Common Ringtail Possum. Both species are quite widespread, especially in the eastern suburbs, and are often treated as pests, damaging gardens and fouling ceilings, in addition to disturbing the sleep of both humans and dogs. Many are killed by dogs, cats and cars, and there is a thriving control industry. Recent changes to legislation have emphasised the desirability of learning to live with possums. In the wetter forests at higher altitudes live the Mountain Brushtail Possum and the large Greater Glider. The smaller gliding possums, the Feathertail Glider and the Sugar Glider, are rarely found now, except in some outer suburban conservation reserves, and in the hills; the Eastern Pygmy Possum, which was probably present in the Banksia woodlands of the Port Phillip Bay coast and in other woodland environments, has gone from those lowlands, but may still occur in the Dandenongs.
It is probable that two species of rat-kangaroo, the Long-nosed Potoroo and the Tasmanian Bettong, inhabited the open forests in the east, but neither are formally recorded for Melbourne. The bettong is extinct on mainland Australia, having left behind little evidence of its occurrence. The larger kangaroos were probably common enough, but are now rarely reported. Black Wallabies do still occur in and near to Warrandyte and in the hills, and Eastern Grey Kangaroos at Melbourne Airport and the nearby Woodlands Historic Park, but both species are subject to predation by dogs, or being hit by motor vehicles.
Bats have probably fared somewhat better than non-flying small mammals; about 15 species of insectivorous bats are recorded from the Melbourne area, and although numbers and distribution have been reduced, it is probable that no species has become extinct. Four species are common within the core suburban area, with additional species being found where remnant natural vegetation is present. Grey-headed Fruit-bats, probably always seasonal visitors, established a permanent camp in the Royal Botanic Gardens and foraged up to 20 km from the city centre.
Only one species of native rodent has coped with settlement-induced change, the Water Rat, which is present in the Yarra River and some of its tributaries. Others, such as the Bush Rat and the Swamp Rat are found no closer than the Dandenongs or the Kinglake area, and the rare Broad-toothed Rat still occurs in small pockets in the Dandenongs. The dingo must have been an early victim of persecution by Europeans, and there are no real records of its presence. Marine mammals are still found in the bay and the resident Bottlenose Dolphins form the basis of commercial dolphin-watching businesses. Australian Fur Seals, which breed at Seal Rocks off Phillip Island, are often seen in Port Phillip Bay, and use such sites as the South Channel Light as resting places.
Introduced mammals include Brown and Black Rats, and House Mice; all are considered vermin and may affect public health. Control is usually carried out at a local level. Red Fox and feral dogs and cats prey on native wildlife, as well as being potential vectors for disease. Rabbits are a problem in outer suburban parklands, reserves and adjacent private gardens, and there is a colony in the Botanic Gardens. Brown Hares are uncommon, being mostly restricted to near-suburban residual pastures. American Eastern Grey Squirrels were introduced about 1870 to the Ripponlea area, spreading as far as Kew but becoming extinct in the 1940s. A small localised colony of Five-striped Palm Squirrels, originally from India, was found in Kew in 1997 but was exterminated. Ferrets, used for rabbiting, occasionally do not return to their owners, but have not become established as feral.