SCIENTISTS have confirmed poorly insulated nest boxes are not killing threatened Australian natives.
But the boxes are not providing any respite from blisteringly hot temperatures at the height of summer, research carried out in the Bendigo area has found.
Southern Cross University wildlife expert Ross Goldingay and Bendigo conservationist Karen Thomas's research is believed to be the first to track temperatures while sugar gliders and threatened tree-dwellers called phascogales are actually sheltering in nest boxes.
Both species have come to heavily rely on nest boxes throughout central Victoria because so many hollow-bearing trees have been cut down over the past 170 years to feed mining and other industries.
Most of the trees that have replaced them have not yet grown old enough to have formed hollows.
Conservationists have become increasingly concerned that the man-made nest boxes they are using as a stop-gap could be getting too hot in summer.
They are particularly worried because climate change is expected to intensify extreme heat days and shrink some species' ranges.
Some conservationists have reported seeing sugar gliders and phascogales leaving nest boxes in the middle of extreme heat days, in what could be a sign of heat stress, Ms Thomas said.
"There is a concern about nest boxes getting too hot for the animals and being detrimental," she said.
The new research has found sugar gliders and phascogales are not dying in their nests and broader studies of populations over the same summer suggest the animals can tolerate the heat.
But it has also proven that nest boxes do not offer them cooler conditions than outside.
Researchers have found temperatures were between three and seven degrees warmer than in unoccupied tree cavities once the barometer rose past 40 degrees.
Ms Thomas said it was unclear what sort of design modifications could help nest boxes better mimic hollow temperatures.
"At least we know that the nest boxes we have right now are mitigating one threat that these animals face, which is a lack of tree hollows."