Also known as rat kangaroos. These small, nocturnal marsupials are endemic to Australia and were once widespread throughout the country.
Bettongs belong to the same family as potoroos and the now extinct Desert Rat-kangaroo. There are five bettong species:
- Eastern (or Tasmanian) Bettong (Bettongia gaimardi)
- Burrowing Bettong (or Boodie) (B. lesueur)
- Brush-tailed Bettong (or Woylie) (B. penicillata)
- Northern Bettong (B. tropica), and
- Rufous Bettong (Aepyprymnus rufescens).
A bettong is about the size of a rabbit, with body length ranging from 30cm to 38cm among species. All bettongs have long tails, roughly equal to body length.
Body weight ranges from 1.2 kg in the smallest species (Northern Bettong) to 2.8kg in the Rufous Bettong, the largest of the group. Males tend to be slightly larger than females. Bettongs have furry coats, ranging in colour from grey to ginger and brown.
Where do bettongs live?
All bettongs have suffered significant declines in their natural distribution following the expansion of agriculture and the introduction of feral predators such as cats and foxes.
In the 1920s, following the introduction of the Red Fox, the mainland population of the Eastern Bettong became extinct; the species is now restricted to Tasmanian, where its population has recently declined alarmingly, and a reintroduced population (inside a predator-proof fence) in the Australian Capital Territory. (1)
The Burrowing Bettong, once found across much of the central, southern and south-western Australia, is now extinct on the mainland (outside of several re-introduced populations within predator-proof fences). It lives naturally on several islands off the coast of Western Australia, and has been introduced to more islands in Western Australian and South Australia. (2)
Similarly, the once-widespread Woylie is now extinct over much of its former range, persisting only in a handful of intensively-baited remnant woodlands in south-west WA, and in predator-proof fences and a few offshore islands. (3)
The Northern Bettong is endemic to north-eastern Queensland, and is now known from only a small number of locations (critically, there are no captive or fenced populations of the Northern Bettong). (4)
The most common bettong is the Rufous Bettong, which is found along the eastern coast of Australia, and remains particularly abundant in Queensland.
According to the International Union for the Conservation of Nature (IUCN), the Woylie is Critically Endangered; the Northern Bettong is Endangered; the Tasmanian population of the Eastern Bettong and the Burrowing Bettong are Near Threatened; and the Rufous Bettong is of Least Concern.
Under Australia’s EPBC Act, the Woylie and Northern Bettong are listed as Endangered, the Burrowing Bettong is Vulnerable, the mainland subspecies of the Eastern Bettong is Extinct.
Depending on the species, bettongs can inhabit arid and semi-arid shrublands, spinifex grasslands, mallee shrublands, temperate woodlands and tall open forests with grassy understories.
All bettongs are nocturnal. During the day many species sleep in well-camouflaged nests – depressions in the ground lined with leaf litter. They carry nesting material with their curved, prehensile (grasping) tails!
Burrowing Bettongs have complex warrens of underground borrows to escape the searing heat of the arid environments in which they live.
At night bettongs emerge to feed. Several species selectively feed on truffles – the underground fruiting bodies of mushrooms – but most also eat a wide range of foods: roots, tubers, leaves, invertebrates, grubs, fruits and seeds.
Bettongs, like bandicoots, are important ecological engineers. Their digging plays an important role in decomposition of leaf litter (thereby reducing fuel loads and fire risk in dry grassy forests and woodlands) and in dispersing fungal spores and plant seeds.
Rufous Bettongs, for example, can travel 1.5km from their nest to feed – a large distance for a small mammal – spreading spores and seeds via their scats, snouts and paws as they move about the landscape.
Bettongs are able to reproduce at any time of the year. The Eastern Bettong’s gestation period is only three weeks long, and while it has only one young per litter, it can produce three young per year in favourable conditions. This relatively high rate of reproduction can lead to ‘extreme fluctuations’ in population growth rates depending on rainfall and drought.
Threats to bettongs
Bettongs have faced and continue to face many threats. They have suffered from extensive loss of habitat due to land clearing for agriculture and development, and ongoing competition for food from stock and feral herbivores, including feral pigs, goats and rabbits.
The introduction of feral predators has been devastating for bettongs, which are particularly susceptible to foxes. Some species also face threats from changed fire regimes, affecting suitable habitat and food availability (e.g. truffles or particular grass species), which may be driven (in part) by the loss of bettongs (and other ground-foraging native species) from the ecosystem.
The small size of many remnant populations is now a threat in itself, with those small populations at risk of extinction from episodic or chance events such as wildfires or floods.