Gilbert’s Potoroo among a handful of rare species that survive on remote WA islands

Few places are more isolated than the islands off the rugged south coast of Western Australia.

Wind-blown and surrounded by dangerous seas, they remain uninhabited and some are almost impossible to access.

But as Australia’s wildlife comes under increasing threat, many of these protrusions play a vital role in conservation – as a safe haven for some of our most endangered species.

On Middle Island, 120 kilometers southeast of Esperance, rangers are working to preserve the world’s rarest marsupials.

Gilbert’s potoro is a small relative of the kangaroo and is critically endangered, with only about 100 left in existence.

Three rangers with their backs to the camera go across the island, the sea and other islands are visible
Rangers spend nearly six hours wandering across Middle Island to download camera footage. (ABC News: Emily Smith)

Every three to six months, rangers from Esperance Tjaltjraak Native Title Aboriginal Corporation travel to the island to download footage from three motion sensor cameras designed to take pictures of the animals and replace their batteries.

Small cans are placed inside the frames of the cameras and filled with food – peanut butter and oats or other treats – in the hope that the smell will attract potoroo and trigger the cameras.

But as ranger Hayleigh Graham describes, it’s hard work.

She is sitting in the bush wearing a cap
Hayleigh Graham is a ranger at Esperance Tjaltjraak Native Title Aboriginal Corporation. (ABC News: Emily Smith)

After a two and a half hour boat ride to the island, rangers spend almost six hours hiking to the various camera locations before returning.

“It’s pretty hard; it’s a different country over here. You climb under trees, you walk along granite cliffs,” she said.

But it’s work they’re happy about.

“It’s pretty good to learn about all this, to walk around all the islands. I love … just love being on Pop’s land, my great – grandfather’s land,” Mr Vincent said.

He is sitting under a tree on the island, in a high-vis jacket, looking at the camera, quite close
Ranger Zane Vincent said working in the Esperance Islands is his favorite part of the job.(ABC News: Emily Smith)

‘Insurance populations’ save money

Middle Island, also famous for its pink lake and for once to be home to Australia’s only pirate, is a relatively new home for Gilbert’s Potoroo.

Aerial view of Lake Hillier on Middle Island with its pink water
Middle Island is home to the vibrant Pink Lake Hillier, which tourists usually see via a scenic flight. (Delivered by: Jaimen Hudson)

The species was thought to be extinct until it was first seen in more than a century near Albany in 1994.

Tony Friend, a research fellow at the Department of Biodiversity, Conservation and Attractions, said a new population was then successfully relocated to Bald Island off Albany.

The idea was to create an insurance population so that if something happened to the original, the species would survive.

It was a wise move – a fire wiped out most of the Indigenous people at Two People’s Bay in 2015.

Aerial view of the fire burning in the Two People's Bay Nature Reserve.
The fire in the Two People’s Bay Nature Reserve in November 2015 decimated the potoroo population and habitat.(Delivered: DPAW)

Funds were then allocated to establish another population, as a substitute, and Middle Island was chosen because of its size, the absence of predators, and for the fact that it has the underground fungi that the potorus eat.

Recent evidence suggested the animals were breeding, with six individuals captured during a research trip in April, three of whom were born on the island.

But it is not yet clear whether the number will continue to rise.

A Gilbert's Potoroo stands in dry leaves in the bushland, staring at the camera and holding its forepaws together
Gilbert’s Potoroo is thought to continue on Middle Island, near Esperance. (GPAG: Dick Walker)

The data from the most recent trip in November has not yet been analyzed, but some potoroo were captured on the motion sensor cameras.

A black and white night image of the potoro
Footage taken from Middle Island in November shows that Gilbert’s Potoroo continues. (Delivered to: DBCA)

The islands’ last refuge for endangered species

As more and more wildlife is threatened by things like climate change, bushfires and wildlife predation, remote islands are often used to “insurance stocks” of critically endangered species.

In close-up, he is wearing glasses and a cap
Tony Friend, from the Department of Biodiversity, Conservation and Attractions, said islands could play an important role in conservation. (ABC News: Mark Bennett)

Dr. Friend said that in Western Australia alone, about 23 or 24 islands were used for these programs, including Bald Island, Dirk Hartog Island, the Montebello Islands and islands off Jurien Bay and the Pilbara coast.

Over the last few decades, he said, the criteria for starting these programs had been refined and the success rate was now around 90 percent.

But he said there were also challenges, as they are difficult to work on, populations need to be carefully managed to prevent inbreeding, and careful research needs to be conducted to ensure they did not affect other native species already on the island.

He sits in a bucket hat by the beach and smiles at the camera
Wayne Gill recently hiked across Middle Island with rangers Hayleigh Graham and Zane Vincent to download images from motion sensor cameras, aimed at the potoroo. (ABC News: Emily Smith)

Wayne Gill used to work for Parks and Wildlife, but now lends his expertise to Esperance Tjaltjraak Native Title Aboriginal Corporation, saying he believes the Recherche Archipelago, with more than 100 uninhabited islands, holds potential for more of these insurance population programs.

In addition to Gilbert’s Potoroo program, he noted that two other islands had been used for similar initiatives – a population of dibbles that have moved to Gunton Island is believed to continue, although noisy scrub birds taken to Mondrain Island have not been discovered since 2020.

A small, furry creature, a cross between a weasel and a mouse.
Dibblers, one of Australia’s carnivorous marsupials, have also been translocated and are doing well on Dirk Hartog Island. (Delivered: Perth Zoo)

“I certainly think it’s in the cards; I do not see why they could not do more,” he said.

“So it’s nice to do what you can to save what’s left.”

She wears high-vis and sits on a can
Hayleigh Graham on her way out to a larger boat that will take all rangers to Middle Island. (ABC News: Emily Smith)

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