With long pinkish-coloured ears and silky, blue-grey fur, the Bilby has become Australia’s version of the Easter Bunny. Unlike the rabbit, Bilby numbers are falling rapidly.
Bilbies now occupy only about 15% of Australia’s landmass. There were originally two species but the Greater Bilby is now commonly referred to simply as ‘the Bilby’ as the Lesser Bilby (Macrotis leucura) is thought to have become extinct in the early 1950s.
Bilbies are believed to have inhabited Australia for up to 15 million years. They feature in the songs and stories of Indigenous Australians, who refer to them by up to 20 different names. While Bilbies co-existed with Indigenous people for more than 40,000 years, it's taken only 200 years of European existence to bring them close to extinction.
The Bilby is about the size of a domestic cat. The male, which is larger than the female, grows to about half a metre from tip to tail, and weighs up to two and a half kilograms. Bilbies typically live for about 10 years.
Where do Bilbies live?
Bilbies are generalist animals and were once found across 70% of Australia. Today they're restricted to the Tanami Desert of the Northern Territory, the Gibson, Little and Great Sandy Deserts, the Pilbara and Kimberley regions of Western Australia, and the Mitchell Grasslands of southwest Queensland.
Bilbies use their strong forelimbs and claws to build extensive tunnels, which provide shelter from the fierce heat and predators. Each Bilby may have up to 12 burrows, with burrows up to 3m long and 2m deep. Bilbies will dig a new burrow every few weeks and often these burrows can also be used by other native animals.
Bilbies are nocturnal, emerging after dark to forage for food. Using their long snouts, they dig out bulbs, tubers, spiders, termites, witchetty grubs and fungi. They use their tongues to lick up grass seeds. Bilbies have poor sight and rely on good hearing and a keen sense of smell. To minimise threats from predators they’ll mostly stay within 250m of their burrow, but sometimes roam further afield depending on the food supply.
While feeding, Bilbies ingest large amounts of dirt or sand, which characterise their droppings. They don’t need to drink water as they get enough moisture from their food. This characteristic contributes to their success in arid regions. Nevertheless, Bilbies are extremely adaptive, and have lived in a range of habitats throughout Australia.
Depending on the food supply, Bilbies reproduce year round, with females typically giving birth to one, two, or occasionally three offspring. It’s rare for all of them to survive to adulthood. Within a fortnight of birth, the young Bilby will make its way along the birth canal into the mother’s backward-facing pouch (which prevents sand collecting as they dig). Babies remain in the pouch for around 80 days. Female Bilbies reproduce from the age of six months.
Once widespread throughout Australia, Bilby numbers fell significantly in the early 20th Century, and 10% of that decline has occurred in just the past 12 years, with the current population estimated to be fewer than 10,000.
The two main threats are competition for food from livestock and introduced species such as rabbits, and predation by foxes and feral cats. Bilbies are known to enclose themselves in their burrows to escape from predators, which will often come in after them.
Changing fire patterns have also affected Bilbies. Large hot wildfires remove the cover provided by vegetation over vast continuous areas making Bilbies more vulnerable to predation. That's why it's very important that traditional patch burning is undertaken by Indigenous rangers in the areas where Bilbies remain. Small patch burns act as fire breaks and reduce the size of large wildfires, they also promote food plants for the Bilby.
The Bilby is listed as vulnerable on the International Union for Conservation of Nature Red List.
What’s Bush Heritage doing?
We're working with the Martu people to help develop the Birriliburu Indigenous Protected Area conservation and land management program in remote Western Australia. This is a partnership is between with traditional owners – the Martu people – and Central Desert Land and Community.
The Birriliburu Indigenous Protected Area occupies 6.6 million hectares of Native Title-determined land in the Little Sandy and Gibson Desert. Our ecologist, Dr Vanessa Westcott, is working with the Birriliburu Rangers to monitor Bilby populations.
“The Bilby population in this area is only just hanging on; with feral cats and foxes representing a major threat.” The Birriliburu Indigenous Protected Area represents the southern edge of their current range – which has been retreating north in recent years. Dr Westcott says. “There’s a great urgency to monitor burrow systems, manage the land and do all that we can to protect the species and help ensure they remain here,” Dr Westcott says.
The Birriliburu Rangers are experts in tracking, finding burrow systems and identifying suitable Bilby habitat. They're passionate about Bilby conservation and want to see the species survive and thrive on their country, as it has for thousands of years.
“If anyone is going to save the Bilby and the other animals in this landscape, it’s going to be Aboriginal people through programs like the Birriliburu partnership,” she says.