The miraculous story of a wallaby, a nursery and naivety

By Angela Heathcote April 17, 2019
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Nailtail wallabies may be back from the brink, but they’re facing the same challenges.

UP UNTIL 1973, the bridled nailtail wallaby was thought to be extinct.

Then a fencing contractor working near what is now Taunton National Park in Queensland, spotted a bizarre looking wallaby, unlike those he’d seen before.

It had a nail-shaped appendage on the tip of its tail and a black-and-white stripe running from the back of its neck to under its arms.

This peculiar wallaby held its arms out as it hopped, which gave it a similar appearance to a classic Charlie the Chimp toy.

The story gets weirder.

The fencing contractor informed his wife, who then matched her husband’s description of the curious wallaby to an article on extinct species in Woman’s Day magazine.

They then contacted the Queensland Parks and Wildlife Service, who confirmed the sighting.

They’d re-discovered the bridled nailtail wallaby.

Since this rediscovery, survival hasn’t become easier for the nailtail.

There are only two wild populations left, which combined have 500 individuals, and one captive population of 2000 individuals in New South Wales.

In 1866, famous Australian naturalist Gerard Krefft wrote that the nailtail was “the most common of all the small species of the Kangaroo tribe”, in stark difference to their population today.

They’ve been introduced to national parks and reserves in Queensland and New South Wales, but their numbers are still declining mainly from predation by cats.

In 2013, mammalogist Diana Fisher from the University of Queensland found that cats stop preying on nailtails once they’d reached three kilograms.

This was critical.

“They’re a hard species to work with,” says UNSW nailtail expert Aly Ross. “Half of the juveniles get eaten by feral cats before adulthood.”

But keeping them in national parks, reserves and other fenced off areas isn’t the whole solution.

There, they face challenges such as inbreeding and prey naivety.

“For us, it was finding the middle ground between the predation they encounter in the wild and the wallaby becoming an easy target upon release,” Aly says.

Prey naivety occurs when a predator is removed making the prey species naive to a threat such as cats or their natural predators.

The captive population at Scotia Sanctuary, located in western NSW are very hard to work with due to being so naive.

In 2015, not-for-profit organisation Wildmob established a nailtail nursery at Avocet Nature Refuge, near Emerald in central Queensland, here a small nailtail population has been struggling against feral cats since 2001.

“The whole point of the nursery is that we’re only keeping them captive for a short period of their life,” Aly says.

The concept: keep nailtails at the nursery until they reach three kilograms.

“We figured if we could protect nailtails until they were three kilograms, then we could double population size.

And they did. The 2017 population count was the highest they’d ever had.

A baby nailtail born and raised in the nursery. She’s been out of the pouch for about a month and she’ll be ready to be released into the wild in 2018.

The nailtail nursery is unlike any other refuge for wildlife.

It’s 14 hectares in size and encloses part of the endangered brigalow woodland, which is home to the native currant bush that the wallabies like to hide in.

Males are separated from females and their young to avoid any inbreeding.

But what makes this place unique is that the wallabies there get little to no interaction with humans.

“A lot of sanctuaries and reserves are massive, but they’re expensive and you need to hire staff that have to routinely check fences.

“Then, if they’re getting caught for monitoring purposes a lot it can impact what they perceive as a threat.”

Rather than doing this, Aly monitors the size of the nailtails via an inconspicuous weigh station they have to travel over to get to water.

Their microchip is scanned so Aly can see which ones have reached the three kilogram mark.

“If I log in and have a notification that one of the wallabies is over three kilos, I’ll plan a trip up there, catch it and release it into the wild.”

Aly and her colleagues at UNSW used lightweight radio-collars, funded by the Australian Geographic Society, to track the juveniles they released from the nursery.

Initial results are positive.

The nursery-raised wallabies initially had a smaller flight initiation distance than wild-raised wallabies, but develop wary behaviour quickly after their release.

This isn’t just good news for the nailtail, it’s good news for other mammals of a similar size as well.

This new conservation strategy could be applied to Tasmanian devils, koala joeys and other species of wallaby.

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