Breeding season for bilbies

Proving a cause célèbre in recent decades, Save The Bilby has become an antipodean alternative to European folklore surrounding the Easter Bunny.

Bilbies are one of Queensland's 15 endangered animals, and a subject of rather serious conservation efforts.

Attempts have even been made to replace the face of Easter in Australia with a bilby (sorry Easter Bunny, you have been demoted) to create public awareness around the bilby's endangered status.

How can you help to save the bilbies? You can buy chocolates shaped like bilbies, you can donate to conserve the vulnerable marsupials, or – if you are in a position like UQ alumni Cassandra Arkinstal l or Kat Castles – you can play a hands-on role in helping bilbies flourish.

*Image:* *Bastetamon* */ Adobe Stock*

*Image:* *Bastetamon* */ Adobe Stock*

“It’s been almost six years that I’ve been volunteering with the Save The Bilby Fund,” Bachelor of Environmental Science graduate Arkinstall says.

“I’m so lucky. I’m doing something I always dreamt about.

“As an extension of that relationship, I’m now undertaking my PhD focused on the reintroduction of bilbies to a fenced reserve in remote south-western Queensland.”

The fenced reserve is situated in the heart of Currawinya National Park, close to the far western border between Queensland and New South Wales.

To provide perspective on its isolated position, Currawinya sits two hours south-west of Cunnamulla in the direction of the Strzelecki Desert.

Currawinya National Park is close to the far western border between Queensland and New South Wales.

Currawinya National Park is close to the far western border between Queensland and New South Wales.

It is one of just a handful of outdoor pockets around Australia where the threatened bilbies can congregate safely, shielded from the predatory threat of wild cats and foxes.

In order to thrive, not just survive, the bilbies are being encouraged to breed via a match-making program that aims to produce 10,000 offspring by 2030.

March to May is prime bilby breeding season, meaning the cuddly creatures are currently in the grip of their hormonal urges.

However, don’t be fooled into thinking this is the animal kingdom’s version of Married at First Sight or Love Island.

Scientists involved are looking for different indicators other than bulging muscles, well-groomed fur or stunning Instagram photos when bringing potential partners together.

“It’s actually something that’s largely left in the hands of geneticists who work with the Greater Bilby National Recovery Team and captive breeding centres like Save the Bilby Fund’s Charleville facility, four hours way,” Arkinstall says.

“What the geneticists are looking for more than anything is to create a genetically diverse population.

“We don’t put the bilbies through physical fitness tests, although before they are released at the fenced reserve at Currawinya, they will spend time creching at Charleville.

“There are large outdoor pens that have been designed to enable bilbies to burrow deep down into the soil, without any risk of them escaping."

“They are also taught how to forage for food that is buried in the pens each day. This helps to prepare the bilbies for life outside of captivity.

“Once the bilbies are released to the fenced enclosure, we cannot control who they breed with, so again we rely on genetics to help select founders that are genetically diverse. This helps to reduce the risk of inbreeding and makes for a more resilient population.

“The risk with a limited gene pool is that a potential threat, such as disease or environmental shifts due to climate change, could result in the loss of a large proportion of the bilbies in short time.”

Images: C. Arkinstall & D. Sargent

The fence at Currawinya with a rainbow in the left corner.

Juvenile bilby being released. Video: C. Arkinstall

Although some people mistakenly believe bilbies are mythical creatures, they are genuinely amazing animals who are full of interesting facts, such as:

Bilbies do not need to drink water. They extract the moisture they require from their food.
A common diet for a bilby consists of vegetation, insects and spiders.
Modern day bilbies are Macrotis lagotis – the last remainder of six similar animals that inhabited Australia. The lesser bilby (Macrotis leucura) became extinct in the 1950s.
Although referred to as ‘rabbit-eared bandicoots’ and ‘arid bandicoots’, bilbies are not strictly bandicoots.
The ears of a bilby can be up to 66 per cent of the length of its body.
They live in spiralling burrows that are up to two metres deep.
While March-May is peak breeding season, bilbies are capable of reproducing year-round.

Bilby at a burrow entrance. *Image: D. Sargent*

Bilby at a burrow entrance. *Image: D. Sargent*

You might think that some of the above attributes would ensure bilby populations remain strong in numbers.

Unfortunately, two other facts about bilbies are that they have poor eyesight, and their tails are crested with white fur, making them easy-to-spot for predators.

“Bilbies never had the opportunity to evolve with cats and that is a major downfall given the proliferation of feral cats in Australia,” Arkinstall says.

“In the limited time since Europeans first arrived in Australia and thought it was a good idea to bring cats and foxes, bilbies simply haven’t had the time to develop an appropriate response to these predators."

“They are essentially naïve to cats and foxes being predators, and can be a sitting target in many ways.”

Shockingly, the introduction of foxes to Australia was primarily for the purpose of sports hunting. Within 20 years of arrival, foxes were declared pests.

While that’s a prime example of harmful human intervention, the current conservation efforts in support of the bilby are helping redress the balance.

Bilby health check. *Image: C. Arkinstall*

Bilby health check. *Image: C. Arkinstall*

“The situation for bilby reproduction at Currawinya is good at the moment as there is plenty of food available on the land,” Arkinstall says.

“The females have been able to maintain good body condition, which is extremely important for breeding, because the milk produced for the offspring is very high in fat.

“The female bilby needs enough fat stores for three-to-four months to rear the young through to independence.

Cassandra holding a bilby. *Image: C Arkinstall*

Cassandra holding a bilby. *Image: C Arkinstall*

“I’ve observed females at Currawinya having up to four litters per year, resulting in between eight and 12 young per female each year.

“However, any suggestion that bilbies themselves could become pests is a misconception. Firstly, their distribution has contracted significantly in the last 200 years. They used to inhabit approximately 80 per cent of Australia, but are now restricted to a few isolated locations.

“Secondly, in times of drought – which heavily impact the areas where bilbies are found – females might only support a single litter and the rates of mortality can be far higher than during productive seasons where food resources are plentiful.”

Image: D. Sargent

Arkinstall lists one of the highlights of her involvement as being able to learn from colleagues such as Kat Castles (nee Lutz), a previous Bachelor of Veterinary Scienc e graduate from UQ.

Now manager of Charleville Bilby Breeding and Creching Facility at the Charleville Bilby Experience, Dr Castles has dedicated a large portion of her life to the battling bilby.

The Charleville Bilby Experience allows visitors to observe the nocturnal activities of bilbies, understand the benefits bilbies bring to the ecosystem, buy a souvenir and learn about other species also under threat.

When the Currawinya facility was established, six founding bilbies were embedded on the site. Another 26 were added soon after.

“Every bilby has their own personality. Some are social butterflies, some like spending time on their own, while others like spending time with their young,” Dr Castles says.

“We are very lucky to have one of our founding bilbies, Tonka, still with us. She is a beautiful, mature female who seems to tolerate people extremely well.

“I will always remember the moment we checked Tonka’s pouch for the first time. I saw one joey’s face, then another, then another. She’d had triplets – which is pretty special for a bilby."

To exemplify the dedication of those behind the Save The Bilby Fund, it took 12 years from the moment a national appeal was launched in 1991 for a bilby fence at Currawinya until it was officially opened in 2003.

It then took another two years before the first bilby was released into the enclosure, and then until 2016 before the Charleville Bilby Experience was opened at a historic former railway station.

Similar to the bilbies, the Save the Bilby Fund lives on despite recent challenges, thanks to the generosity of those who add their support.

“Now we have people from across the world who support us,” Dr Castles says.

“People of all ages and demographics get behind the bilbies, including students enrolled overseas.

“Personally, I see every new joey as a joyous moment. We love each and every new face we encounter.

“Bilbies are such brilliant parents. They really care for their young.

“When you think of the ginormous effort of a mother to cart up to three babies around, supplying milk to them in an incredibly arid environment, perhaps already pregnant with her next children, it’s hard not to be impressed.

“One of the reasons that motivated me to be a vet was making a difference, and it’s very clear with bilbies that helping them truly does make a difference.”

This Easter, no matter where you live, you too can help Save The Bilby by pledging your support.

Image: D. Sargent