In good hands ... one of the golden-backed tree rats that the Australian Wildlife Conservancy wants to ensure have a long and secure future. Photo: Nick Moir
IT WAS once so common it was considered a pest, found running through the rooftops of many houses in Broome.
But in a narrow, rainforest-filled gorge, 350 kilometres from the West Australian pearling capital, ecologist Katherine Tuft has had no luck catching a golden-backed tree rat.
And then, as she inspects the fifth cage she placed out the night before, Dr Tuft finds what she is looking for.
''These guys used to be across much of northern Australia but they've really contracted back and now the north-west Kimberley is the only place they are,'' Dr Tuft, from the non-profit conservation group the Australian Wildlife Conservancy, said.
The unfortunate case of the native rodent is representative of the plight of more than half of northern Australia's small mammals, such as the northern quoll and golden bandicoot, whose ranges have contracted and whose populations have plummeted in the past 20 years. For these species, the north-west Kimberley is the last stand.
In an attempt to guard these creatures the Australian Wildlife Conservancy has taken over the management of a new property in the region, the Artesian Range, where a team of ecologists have found many rare species, including several the scientists had never seen.
The chief executive of the conservation group, Atticus Fleming, said the conservancy planned to manage the reserve by eliminating or minimising the threats that have pushed many of these animals to this narrow corner of northern Australia, such as feral animals and fire.
''We've come in here in the nick of time,'' he said.
A wildlife conservation professor, Chris Johnson, said most mammals below a body size of a kilogram were in steep decline in northern Australia.
''It looks like one big chunk of the biodiversity of those ecosystems is disappearing. And it is happening really fast,'' Professor Johnson, from the University of Tasmania, said.
Several key species had reached their tipping point, and if their populations fell any lower it was unlikely they would ever be able to recover.
''Once a species has got down to a very small population it has lost a lot of genetic variation [which] means it loses some fitness and the ability to adapt to threats or cope with disease,'' he said.
A small population was also vulnerable to local threats such as a drought or dramatic bushfire.
But if the north-west Kimberley remained a sanctuary for these key species, and they were able to flourish, they could be re-introduced to parts of their former range, Professor Johnson said.
The reporter travelled to the Artesian Range Sanctuary courtesy of the Australian Wildlife Conservancy.