Weighing about 200g, the rat is listed as vulnerable nationally and endangered in the NT where it has only been recorded three times by Europeans between 1901 and 1969.
It has distinctive features such as a long brush-tipped tail that is partially white, along with white coloured feet.
An elderly indigenous woman told scientists she had spotted the animal crossing a bush track when shown a collection of stuffed animals that were touring Arnhem Land in 2007 as part of an “endangered mammal roadshow”.
But a recent seven-day trapping expedition to western Arnhem Land involving TOs from the area has failed to find any trace of the animal.
“That one that we were looking for, we are starting to be a bit concerned,” said senior ranger Dean Yibarbuk.
“We thought these animals (known by the local name of Korberr) were still around but now we can’t find them.”
Biodiversity scientist Carol Palmer said the decline of the golden-backed tree-rat from the NT and drier areas of Western Australia was symptomatic of a more general decline in mammals in northern Australia.
“We didn’t find any sign of the golden-backed tree-rat on this expedition, and would have expected to catch and see a greater diversity of mammals,” she said.
“This most recent survey has confirmed what we already know, that the diversity and abundance of mammals in the Top End are declining rapidly, and any opportunity we have of finding the remaining mammal populations so that we can manage those populations is essential.”
In February this year, over 40 scientists and land managers released research which warned Northern Australia was facing a fresh wave of potentially catastrophic mammal extinctions.
Australia already has the worst extinction record in the world, with 22 mammals becoming extinct in the last 200 years.
“What we are seeing is a reduction, both in the abundance of mammals, but also for some species really catastrophic declines across their range,” Dr Sarah Legge, from the Australian Wildlife Conservancy, said at the time.
Ms Palmer said the patchy nature of food resources and the tree-rat’s susceptibility to disturbance could explain the decline of its population, particular in the more inland areas.
She said that although the animal was not known to be too tricky to trap it was too soon to say if had been wiped out of the NT.