Land clearing is leading to tree mammal numbers declining in northern Australia as researchers fear it could end in extinction.
A study deployed 187 nest boxes in trees in Garig Gunal Barlu National Park in the Northern Territory to see whether the number of hollows was contributing to a decline in mammals that use the habitats.
It found 67 per cent of the nest boxes were used by tree mammals at least once.
The replacement for natural tree hollows was used primarily by brush-tailed rabbit rats followed by savanna gliders, black-footed tree rats, fawn antechinus and northern brushtail possums.
"This showed that these declining arboreal mammals were searching for and using new dens where natural hollows were reduced at a local site," lead author Dr Leigh-Ann Wooley, from Charles Darwin University, said.
Dr Wooley said the high number of mammals using the nest boxes was unexpected.
"We were sceptical that mammals would use the nest boxes we deployed at all, never mind that their nest box use would be strongly associated with tree hollow density at a site," she said.
Mammals inhabiting trees are important to the environment as they disperse seeds and pollinate plants unique to the area.
Researchers are concerned if the loss of trees and natural hollows continues there could be a sharp decline or extinction of these critical creatures.
"Amongst the multitude of threats interacting to cause the decline of these species, such as inappropriate fire, introduced ungulates, and feral predators, habitat quality should not be disregarded when managing threats to improve outcomes for these mammals," Dr Wooley said.
Protecting savanna eucalypts - where tree hollows for the mammals to live are often found in the region - is crucial to the future of the species.
"Good quality habitat with ample tree hollows for denning and nesting, as well as high quality and abundant food sources, will buffer against other serious threats to these animals," she said.
Without the hollows and with lower tree density, the mammals are threatened by other hazards like predation by feral cats as they are forced to spend more time on the ground travelling to alternate habitats.
Halting land clearing, protecting hollow-bearing eucalypts and optimising fire regimes to ensure hollow densities and fruiting shrubs are increased are among the solutions to protect the trees and the species.
The research was published in the journal Forest Ecology and Management.
