Bilby
Bilby - Australia's Easter bunny
Macrotis lagotis
Among the hot, dry grasslands of western Queensland, the greater bilby lives far from the public interest surrounding its conservation. As one of Queensland's 16 Endangered mammals, the bilby is the subject of intense conservation efforts. This includes attempts to replace the Easter bunny with the Easter bilby in Queensland, to make the public aware of this important animal's plight.
The Endangered bilby. Photo: DERM
What does it look like?
The bilby is the size of a rabbit, and has a long-pointed nose, silky pale blue-grey fur with patches of tan, big ears and a crested black and white tail. They measure up to 55cm in body length, and their tail can be up to 29cm long. Males weigh 1-2.5kg, while females are lighter and weigh 800g-1.1kg.
These ears are not for decoration, as they provide sharp hearing. This feature, combined with a strong sense of smell, is important for the bilby when looking for food. But all its senses aren't that effective because the bilby can't see very well. Interestingly when they run, they keep their nose down and this contributes to their unusual gait.
The re-discovery of the bilby
The bilby, also known as the greater bilby, once ranged over most of mainland Australia. But the arrival of exotic predators has eliminated bilbies from most of their former range. Its closest relative, the lesser bilby, is extinct.
For many years there were no records of bilbies in Queensland, and some thought that the species had gone extinct in the state. The then Queensland National Parks and Wildlife Service (QNPWS) surveys in Diamantina Shire between 1981 and 1985 failed to find any bilbies, although they did highlight suspected bilby habitats. It wasn’t until QNPWS focused more lengthy surveys on these suspected areas and historic sites that bilbies were rediscovered in 1988.
The distribution of the bilby
Now the bilby is found in a few places in western Queensland. Queensland's largest remaining group of bilbies lives in one area west of the Diamantina River in the State's far west, which includes populations in Astrebla Downs National Park and Diamantina National Park. Bilbies are also found in Currawinya National Park. Recently, a large bilby population was discovered on a stock route in Diamantina Shire, and further bilby populations are believed to exist on other stock routes.
Across the rest of Australia, the bilby is restricted to parts of the Great Sandy, Gibson and Tanami deserts in central Australia and the Pilbara and west Kimberley in Western Australia.
Bilbies have also been introduced to various sites including Scotia Reserve in New South Wales, Western Australia, and South Australia.
This is where bilbies live in Queensland. The colours show the estimated distributions: dark green is for pre European settlement; mid green is for 1936; light green is for 1970; and black is for 2000. Image DERM)
Where does it live?
Bilbies can live in a range of habitats that include Mitchell grass plains, sandstone ridges, gibber plains, rocky soils with little ground cover, hummock and tussock grasslands, and acacia shrublands.
A powerful digger, the bilby makes spiral-shaped burrows up to three metres long and almost two metres deep. The reason they are so deep is to keep them safe from predators, and also to keep them at a constant temperature of 23 degrees Celsius. The bilby stays in its burrow during the day, looking for food well after dark. A bilby may have up to a dozen burrows – some for sleeping in and the others for escaping into. When returning to the burrow after a night of foraging, the bilby back-fills the burrow to prevent predators from entering. The burrow contains no nesting material and the entrance is often against a termite mound or small shrub.
A burrow takes a lot of energy to dig, but provides important protection, so bilbies will often repair and use old burrows. Some of these burrows could date back hundreds of years.
A bilby burrow (photo Mellisa Mayhew)
What does the bilby eat?
Bilbies are omnivores, which mean they feed on a range of foods including seeds, fungi, bulbs, and insects such as grasshoppers, beetles, spiders and termites. When looking for food, the bilby digs small holes up to 25cm deep. These holes are scattered over bilby feeding areas.
A bilby feeding hole – the footprints and tail-mark can be seen just below the hole (photo Mellisa Mayhew)
The bilby has several distinctive features that it uses to find food. It uses its big ears and sharp sense of smell to find food, and it has a long, skinny tongue that it uses to lick up seeds from the ground. However, this feeding style means the bilby eats a lot of sand. In fact, 20-90 percent of its waste can be sand! Another feature is that it often eats the exoskeletons of insects, which shine in the light when their scat is broken open.
A bilby scat (photo Peter Young)
The bilby gets most of its water from its food rather than from drinking, which means it can survive in habitats with no standing water.
What is the life history of the bilby?
Bilbies live alone or in a pair. In the wild, the bilby lives to about seven years old, and they begin to breed when they are six months old.
How does the bilby breed?
The bilby is a prodigious breeder, and can produce up to eight young a year. Female bilbies usually give birth to two young, and as they can breed throughout the year, they can give birth up to four times per year. Additionally, female bilbies have a very short gestation period of just 14 days.
Like another Endangered burrowing marsupial, the northern hairy-nosed wombat, female bilbies have a backward-opening pouch, which prevents soil entering the pouch when they are digging.
Young stay in the pouch for 80 days, and then once they are out of the pouch they stay in their mother’s burrow for a couple of weeks. During this time their mother is very busy moving in and out of the burrow so that she can forage outside for food and return regularly to feed her young.
Recovering the bilby
As bilbies can live in a variety of habitats, eat a range of foods, survive without standing water, and breed fast, they should be more common then they are. So why isn’t the Outback filled with bilbies?
In Queensland, the impact of predators such as foxes and cats has had the greatest effect on bilby numbers and continues to be the most serious problem.
Additionally, bilby habitat is getting smaller and more fragmented, and existing habitat can deteriorate through grazing and trampling by domestic and feral livestock, competition for food from rabbits, and other factors such as changed fire patterns.
The conservation of the bilby in Queensland will require providing adequate habitat where numbers of foxes and feral cats can be reduced, and where the other threats to bilbies can be managed.
A large part of the bilby's Mitchell grassland habitat in the Channel Country is now included in Astrebla Downs National Park, which will assist in protecting this important bilby colony.
There is also ongoing research to better understand how bilby populations are changing over time. In 2000 teams of researchers surveyed south-west Queensland from the air and the ground, and there is annual monitoring of bilby burrows in the Diamantina area.
The Currawinya National Park bilby population
Currawinya National Park is the only site in Queensland where bilbies have been re-introduced into the wild.
In order to prepare a site for the release of bilbies, a predator-proof fence was constructed in the Park, which encloses about 20 square kilometres of habitat. This fence is of a special design, with tight mesh to prevent any predator from squeezing through, an outward-hanging top section to prevent cats from climbing over, and a buried skirt that prevents predators from burrowing in (and bilbies from burrowing out). Numerous people across Australia contributed to the Save the Bilby Fund, which provided the money to build the fence.
The completion of the fence in 2001 was followed by predator control to remove any foxes, cats and other animals that threaten bilbies from within the enclosed area. However, because of drought no bilbies could be released until December 2005.
The predator-proof fence in Currawinya National Park (photo Mellisa Mayhew)
With the arrival of rain in 2005, four bilbies – three females and a male – were released into the enclosure as a trial. The release was a success as within hours the bilbies had started to dig burrows and eat natural foods. This small population has been increased with further releases and natural breeding. Captive breeding for release into the Currawinya National Park enclosure is occurring at the Department of Environment and Resource Management (DERM) office at Charleville, and on the Gold Coast at Dreamworld and the DERM David Fleay Wildlife Park.
Without the pressures of predation, the Currawinya population of bilbies has continued to expand and has given hope for future releases at other sites.
Inside the bilby enclosure in Currawinya National Park (photo A. Howe)
How you can help the bilby
If you are in western Queensland and see a bilby in the wild, please report the sighting to the local DERM office.
You can also help the bilby and other Australian wildlife by supporting threatened species projects and caring for our native plants and animals. This will ensure our native animals survive where they belong - in the bush!
Further information on the bilby -National recovery plan for the Greater Bilby Macrotis lagotis
Last updated: 03 September 2009