Gilbert’s Potoroo among a handful of rare species surviving on remote Australian islands
Rangers from the Esperance Tjaltjraak Native Title Aboriginal Corporation are monitoring a small population of Gilbert’s Potoroos on Middle Island
An insurance population of the potoroo was translocated to the remote island, off WA’s south coast
Many remote islands are now being used as homes for critically endangered species, as mainland populations come under threat from bushfire and feral predation
Few places are more isolated than the islands off Western Australia’s rugged south coast.
Windswept 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 outcrops are taking on a critical role in conservation — as safe havens for some of our most endangered species.
On Middle Island, 120 kilometres south-east of Esperance, rangers are working to preserve the world’s rarest marsupial.
The Gilbert’s Potoroo is a small relative of the kangaroo, and is critically endangered, with only about 100 left in existence.
“We’re just seeing if the population can grow, because on the mainland they’re getting eaten by foxes and wild cats,” ranger Zane Vincent said.
Every three to six months, rangers from the Esperance Tjaltjraak Native Title Aboriginal Corporation travel to the island to download footage from three motion sensor cameras, designed to snap pictures of the animals, and replace their batteries.
Small canisters are placed within the frame of the cameras and filled with food – peanut butter and oats or other treats – in the hope the smell will attract potoroos and trigger the cameras.
But, as ranger Hayleigh Graham describes, it is difficult work.
After a two-and-a-half-hour boat ride to the island, the rangers spend almost six hours trekking to the different camera sites before making the return journey.
“It’s pretty hard; it’s different land over here. You’re climbing under trees, you’re going alongside granite rocks,” she said, “You’re pretty much bush-bashing all the way through.”
But it is work they are happy to do.
“It’s pretty good learning about all this stuff, going around all the islands. I love … just love being on Pop’s country, my great grandfather’s country,” Mr Vincent said.
‘Insurance populations’ save Potoroos
Middle Island, also famous for its bright pink lake and for once being home to Australia’s only pirate, is a relatively new home for the Gilbert’s Potoroo.
The species was believed extinct, until it was spotted for the first time in more than a century near Albany in 1994.
Tony Friend, a research associate with 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 if something happened to the original one, the species would survive.
It was a wise move – a fire wiped out most of the original population at Two People’s Bay in 2015.
Funding was then granted to establish another population, as a replacement, and Middle Island was chosen for its size, absence of predators and for the fact it has the underground fungi which the potoroos eat.
Recent evidence suggested the animals were breeding, with six individuals caught during a research trip in April, three of which were born on the island.
But it is not yet clear whether numbers will continue to grow.
“Potoroos live for about 10 years so there’s plenty of time for that little population to build up,” Dr Friend said.
The data from the recent trip in November has not yet been analysed, but some potoroos were captured on the motion-sensor cameras.
Islands last refuge for endangered species
As more and more wildlife come under threat, from things like climate change, bushfires and feral predation, remote islands are frequently being used for “insurance populations” of critically endangered species.
Dr Friend said in Western Australia alone about 23 or 24 islands were being used for these programs, including Bald Island, Dirk Hartog Island, the Montebello Islands and islands off Jurien Bay and the Pilbara coast.
Over the past few decades, he said the criteria for initiating these programs had been refined, and the success rate was now about 90 per cent.
But he said there were also challenges, in that they are difficult to work on, populations have to be carefully managed to prevent inbreeding and careful research had to be done to ensure they did not impact other native species already on the island.
Wayne Gill used to work for Parks and Wildlife, but now lends his expertise to the Esperance Tjaltjraak Native Title Aboriginal Corporation, and said he believes the Recherche Archipelago, with more than 100 uninhabited islands, hold potential for more of these insurance population programs.
As well as the Gilbert’s Potoroo program, he noted two other islands had been used for similar initiatives – a population of dibblers translocated to Gunton Island are believed to be persisting, although noisy scrub birds taken to Mondrain Island have not been detected since 2020.
Brush-tailed bettongs are back. These tiny endangered marsupials have been reintroduced to mainland South Australia after disappearing more than a century ago.
A native mouse that was thought to be extinct was found off Western Australia recently, The Guardian reported. Gould’s mouse was found on several small islands after not being found on the mainland.
“I think it’s definitely on the cards; I don’t see why they couldn’t do more,” he said, “We’ve already stuffed the planet up quite a bit through our activities.
“So, it’s nice to do what you can to save what’s left.”
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