This elusive possum is believed to be extinct outside Victoria. Now, ecologists have made an “amazing” discovery

An endangered possum, considered isolated Victoria, was found in the Alps National Park in New South Wales.

Previously thought to be extinct in the state, the Leadbeater's opossum was found in Kosciuszko National Park, at least 250 kilometers from the closest witnesses in Victoria.

Among millions of photos, a trawl of seven small creatures found in 10 seconds, Healesville Sanctuary and the Australian National University confirmed the discovery of the NSW Department of Environment.

Leadbeater's possum, the animal logo of Victoria, has big eyes and a dense tail. It relies on dense wet areas in old growing forests and nests in hollow nests, and it takes more than 150 years to form.

One of seven images of lead worm possum set up by NSW Department of Environment cameras in Coscosco National Park. Photo: DCCEEW

"It's great to see a unique shrub tail waving in a row of images on the screen," said Dr Fred Ford, senior threat species officer for energy, environment and water at the NSW Department of Climate Change.

“It jumped out to me,” he said. “This discovery highlights that you have to search for the world there to find these rare species.

“You may not be looking specifically for things you find, but the more you look, especially with modern technologies like remote cameras and environmental DNA, the more chances you have to find them.”

There are less than 40 Leadbeater possums in Victoria. Photo: Dan Harley

NSW Environment Minister Penny Sharpe marked the discovery as “Extraordinary”.

“To get ecologists to find a needle in a large number of millions of images shows their commitment to the cause of conservation and proves that the NSW government’s threatening species officials are doing some of the most incredible work,” she said.

“This particular discovery at Coscosco National Park reiterates why the government has taken action to remove invasive species to protect Australia’s only continental alpine region spread across the NSW and Victorian borders.”

A recent survey found that the national park’s Bloomby population had been greatly eliminated by aerial shooting, which Sharp said is important in providing the right conditions for native species.

The NSW government said Brumby Cull in Coscosco National Park helped native species. Photo: Mike Bowles/Guardian

Ecologists will review past surveys of Kosciuszko to see if more endangered possums can be found and put in a new camera to help find them.

Leadbeater's possum, known as the "Forest Fairy", was considered extinct because their shocking people were rediscovered near Marysville in 1961.

Most of today's habitats have lost most of their habitat due to logging and development, with less than 40 of today's lowland species occurring in the Yellingbo forest area in eastern Melbourne.