Koalas could suffer a "huge reduction" in numbers unless Australia changes its land management practices to help mitigate the impact of climate change, a study has found.

The research, led by the University of Sydney, involved the tracking of 40 koalas via GPS over three years on farmland around Gunnedah, in north-west NSW.

The results showed that the koalas moved between various trees to feed on eucalypts during the night, before moving to more shaded trees during the day to shelter from the rising temperature.

Koalas prefer trees in cooler low-lying areas such as gullies, rather than in open plains or hilltops, to shelter in, according to the study.

The research shows koalas are at heightened risk of heat stress, dehydration and eventual death if these shaded trees are cleared.

This risk is set to be compounded by the predicted increase in heatwaves due to climate change. In 2009 a heatwave killed a quarter of the koalas tracked by the University of Sydney study.

"Koalas have a fussy diet of eucalypts, so they need a range of these food trees, but they need shadier trees too such as the Belah and Kurrajong varieties," Matthew Crowther, who led the study, told Guardian Australia.

"One of the biggest problems we face is the loss of these trees. As heatwaves increase, we'll need more of these trees to maintain a healthy population as koala distribution changes.

"Koalas have to weigh up a lot of things. They rest for 20 hours a day and do most of their feeding at night, moving between a number of trees to meet their nutrient requirements. They need that mixture of trees to survive.

"If we don't plant enough big trees, we will find koalas perish if heatwaves increase. They are large animals that live in trees, they can't burrow down or fly away to get away from the heat. We could see a huge reduction in numbers if habitat is not kept properly."

In the short term, koalas face the threat of shrinking habitats but they are also considered particularly vulnerable to climate change owing to their limited diet of eucalypts and their tree-dwelling nature. Studies have shown that the composition of eucalypts changed in warmer temperatures, degrading it as a food source for koalas.