Alert, active, agile, the small marsupial pauses in the fork of the tree, caught in the spotlight beam, then rapidly scampers around the trunk, its black brushy tail visible and distinctive.
Rarely seen, the brush-tailed phascogale is a formerly widespread and characteristic species of temperate woodlands of southern Australia.
With an extraordinary life-history, in which all males die after mating, it’s one of many fascinating species that depend on woodland ecosystems – but like these woodlands, the distribution of many species has been greatly reduced and fragmented.
For many people, temperate woodlands are the quintessential Australian environment, evoking memories of living in or travelling through ‘rural’ Australia. Woodlands occur from Queensland, through New South Wales and Victoria to South Australia – mainly inland of the Great Dividing Range – and in south-west Western Australia and the Midlands of Tasmania.
Occasional ‘scar’ trees are reminders that woodland ecosystems were occupied by Aboriginal people for millennia.
Vast areas of woodlands have been cleared to form the ‘sheep-wheatbelt’ agricultural zone across southern Australia. Most woodlands now occur as isolated blocks, large and small; some as conservation reserves or forest reserves, many as remnants in and amongst farmland and along stream systems. For the native mammal fauna, profound changes have occurred.
Woodlands have a relatively open tree layer, typically dominated by 10-30m tall eucalypts, over a ground layer of grasses, herbs and shrubs. The size, age and spacing of trees, shape the habitat for many mammals.
Large, old trees are a key habitat component, important for providing resources such as wide canopy foliage, regular flowering, a large surface area of bark on trunk and branches, and a diverse range of hollows and crevices.
Arboreal mammals, from the tiny feathertail glider to the mid-size squirrel glider and large common brushtail possum, depend on tree hollows for den sites. But not just a single hollow – individuals regularly move between multiple hollows within their range, carefully selecting those of suitable entrance size, form and orientation.
Insectivorous bats are the ‘invisible’ mammals: most people would be astonished to know that 6-8 species of bats may be foraging at night in a woodland environment. These species also require tree hollows and crevices for daytime roosts and they show a high level of selection for suitable sites.
The widespread lesser long-eared bat, for example, favours roosts in dead trees, squeezing through entrances about 2.5cm in diameter, whereas the Gould’s wattled bat commonly selects roosts in dead limbs in large live trees. With an exquisite ability to navigate and to catch insect prey at night by using echolocation (a type of sonar system), many of these species weigh less than a single 50 cent coin!
It’s the ground-dwelling mammals, particularly those of medium size (0.1kg to 5kg) that have experienced the greatest impact of changes to temperate woodlands. Bandicoots, rat-kangaroos, small wallabies, quolls and large rodents, have all but disappeared from woodlands, with notable exceptions including parts of Tasmania and southern Western Australia.
Tragically, some are globally extinct, such as the white-footed rabbit rat and the eastern hare wallaby. Others, such as the brush-tailed bettong (woylie), eastern quoll and eastern barred bandicoot, hang on in tiny parts of their former range.
It’s not just the local loss of these species that’s important but also the loss of their ecological function in woodlands, particularly the ‘ecosystem engineering’ effects of species that excavate burrows or forage by digging pits in the soil (e.g. southern bettong, short-beaked echidna).
Research has shown that these diggings play an important role in water infiltration into the soil, in trapping litter and recycling nutrients, and in creating favourable microsites for plant germination and growth.
Protection and restoration of temperate woodlands and their mammal fauna is now an urgent and important task. Preventing further clearing, reducing threats from invasive plants and exotic animals, controlling domestic stock, facilitating natural regeneration and replanting, protecting large old trees, and re-introducing locally extinct species are all examples of the kinds of actions needed.
With their distinctive character and beauty, temperate woodlands are a vital part of the heritage of all Australians.
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The nominees are:
Brush-tailed phascogale (Phascogale tapoatafa), patchy distribution around the coast of mainland Australia
They have a black, bushy ‘bottlebrush’ tail, with hairs up to 4 cm long, that they use to distract predators and to help balance.
Brush-tailed rock wallaby (Petrogale penicillata), southern QLD to eastern NSW and Victoria.
They use their powerful hind legs to repeatedly ricochet off rock, easily traversing cliff faces and rock gullies, while using their long tails for balance and as a rudder to steer them.
Southern bent-wing bat (Miniopterus orianae bassanii), south-west Victoria and south-east SA
By congregating in large numbers at one of their key maternity caves, they can transform the conditions in the maternity chamber of the cave to make it more humid and up to 12 degrees warmer.
Eastern barred bandicoot (Perameles gunnii), south-west Victoria
Their conical-shaped head is used in conjunction with some powerful front legs to dig crater-shaped holes in the dirt, aptly called “snout pokes”.
Kangaroo Island dunnart (Sminthopsis grisoventer aitkeni), western end of Kangaroo Island
Radio telemetry has shown they have a small home range with movements of only 200-300m from their shelter sites.
Gilbert’s Potoroo (Potorous gilbertii),
After missing from the records for 120 years and thought extinct, they came “back from the dead” when rediscovered in 1994.
Honey possum (Tarsipes rostratus), south-west WA
They have the largest testes relative to their size and longest sperm of any mammal, but produce the smallest young.
Eastern pygmy possum (Cercartetus nanus), eastern Australia, including Tasmania
They have a long prehensile tail that is often used as a fifth limb to carry nesting material back to hollows.
Mahogany glider (Petaurus gracilis), northern QLD
They are only found along a narrow sliver of suitable habitat in north Queensland – about 122km long and 100km wide – between about Tully and Ingham.
New Holland Mouse (Pseudomys novaehollandiae), fragmented distribution across Tasmania, Victoria, NSW and QLD.
Despite their small size, they can create intricate burrow systems in sandy soils in which they nest during the day, raise their young, and stay safe during fire.
Northern bettong (Bettongia tropica), northern QLD
They are confined to a narrow band of tall, open eucalypt forests and woodlands along the western edge of tropical rainforests.
Numbat (Myrmecobius fasciatus), south-west WA
They have specialised fur that traps heat from the sun, giving them the highest solar heat gain of any mammal.