The Bilby - The Rabbits Rival
Scientific Name: Macrotis lagotis
Conservation Status: Vulnerable
Easter is the time to celebrate new life and although the rabbits certainly represent new life, (a female as young as 6 months can produce up to 50 young a year) thats not the kind of life Easter is in celebration of. The Easter Bunny may now be in decline due to a movement that set out to change the look of the supermarket shelves, but more importantly, the attitudes of the Australian Pshyce. Australia has recieved a new Easter mascot, the Bilby.
The greater bilby Macrotis lagotisis a small mammel whose populations and potential habitats have been severly depleted due to direct competition of rabbits and foxes. There is presumed to be only several hundred left in the wild and predicted to become extinct in the wild. The lesser bilby Macrotis leucra is presumed extinct(Hoser, R. 1991). The bilby resembles the rabbit in only two ways, it has large ears and digs burrows. The one significant difference is that the bilbly's population and habitat has suffered from a sharp decline. This is largely to the rabbit, foxes and farming which have either destroyed the bilby or its habitat. Let us hope that this new mascot of life may benefit, not just by populating the supermarket shelves, but by an awareness of Australians that may help the Bilby raise its own population and save it from extinction.
The long hairless ears of Bilbies are probably important in keeping them cool as well as for hearing predators. Bilbies have long snouts and long slender tongues. Although they have poor vision, their senses of smell and hearing are very good. This is important for finding food and avoiding danger.
The strong front limbs have three toes with claws and two without claws which Bilbies use to burrow rapidly. The hind limbs are slender and rather like a kangaroo's with a very large middle toe. The hind limbs are used for grooming.
Bilbies are now only found in scattered parts of the Tanami Desert in the Northern Territory, in the Great Sandy Desert, Gibson Desert, Pilbara and Kimberley regions of Western Australia and an isolated population lives in south-west Queensland.
Bilbies used to live in many different habitats across Australia wherever the climate was fairly dry. Areas with better soils and rain were changed by farming and grazing, leaving only the very dry regions of inland Australia.
Bilbies are now mainly found in grasslands and acacia shrublands with spinifex and tussocks. They only live where there are few rabbits and foxes.
Bilbies build burrows that spiral downwards to a depth of about two metres. Each animal may use up to a dozen burrows, each with only one entrance that is usually hidden by a small bush, grass tussock or termite mound.
Bilbies are nocturnal (active at night) and shelter in their burrows from the heat of the day. At night, a Bilby may travel up to five km as it searches for food. Bilbies are omnivorous (feed on animals and plants) and will feed on whatever food is available each season. They eat insects and insect larvae as well as bulbs, fruit, fungi and seeds which they lick from the ground with their long tongues. Bilbies also use their front feet to dig for food.
Generally, Bilbies live alone but they may live in small groups of two to four animals, when the home ranges of an adult male, female and their young overlap. It is possible for young to be born throughout the year, but breeding may depend on rainfall and the amount of food around. Bilbies have from one to three young which stay in the pouch for about two and a half months. They stay with their mother for another two weeks before leaving the home burrow. No one knows how long they live in the wild, but captive Bilbies can live for about five years.
Bilbies are preyed on by foxes and feral cats. They have to compete for food with rabbits and livestock. Their supply of food has also been affected by changes in the number and strength of fires since European settlement in Australia.
Bilbies can move around to find food but in severe drought they depend on areas with a good supply of food. Other animals, including rabbits and cattle, also depend on these patches, which become overused, and may not be able to keep Bilbies and other native species alive during drought. After a long drought, colonies of Bilbies may have a smaller chance of increasing in numbers. In this way the Bilby population could decrease every time there is a long drought.
Bilbies now live in small scattered populations often a long way from other Bilby populations. These populations may not be able to survive a disaster such as disease, fire or severe predation.
In Western Australia, Bilbies live on protected land in the Gibson Desert Nature Reserve, in the Great Sandy Desert at Rudall River National Park and the proposed Percival Lakes Nature Reserve.
In the Northern Territory studies over the next few years will look at the movement, growth, breeding, habitat use and survival of Bilbies in the wild. This should show if numbers are decreasing or remaining the same, what is stopping the population from increasing and spreading, and how much predation Bilby populations can survive. Since 1980 there have been some attempts to reintroduce Bilbies into Watarrka National Park (350km south of Alice Springs). These did not succeed partly because of cat predation.
In south-west Queensland Bilbies live in the new Diamantina Lakes National Park, but the biggest population is found on private land. In these areas burrows are being located to find out how many Bilbies there are and where they live, and their ecology is also being studied. A study of feral cats in the same area should show how they are affecting the survival of Bilbies.
The Lesser Bilby was last reported alive in north-eastern South Australia in 1931 and is now presumed extinct. This bandicoot had white fur along the top of its tail and was smaller and less colourful than the Greater Bilby. The Lesser Bilby closed the entrance to its burrow when inside. It was noted to feed on small rodents and mice, as well as seeds. Females reared up to two young at a time.
Endangered: An animal or plant species that is in danger of extinction and will probably not survive if the threats to it continue.
Vulnerable: An animal or plant species that will probably become endangered if the threats to it continue.
Stoddart, E (1992) Bandicoots and Bilbies of Australia. Bimberi Books, ACT.
Strahan R (1983) The Australian Museum Complete Book of Australian Mammals. Angus and Robertson.
Greater Bilby Recovery Plan. Available soon from the Australian Nature Conservation Agency for $10.
Illustrations copyright Sue Stranger, Kaye Kessing and Patrick Cook (most not in the electronic edition)
February 1994
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