Hundreds of grey-headed flying foxes have been brought to the hospital after their rescue centre in New South Wales was evacuated. They're a species of native bat that is under threat, but they're being nursed back to health thanks to the team of vets and nurses.

Terri Irwin, owner of Australia Zoo and wife of the late Steve Irwin, said the hospital team saw a 750 percent increase in their flying fox intake in September.

"We saw fires in our region in November. And now Australia Zoo and the Sunshine Coast is safe, but we're able to offer a safe haven for wildlife further south needing help."

Injured possums, birds, koalas and even platypuses are recovering at the hospital.

The bushfires are having a horrific impact on the koala population - an estimated 5000 were wiped out in the recent Kangaroo Island blaze alone.

Irwin said a koala's instinct is to go up a tree because that's where safety is, but that is contributing to their demise.

"With a hot fire, the eucalyptus trees have so much oil in their leaves that they ignite and actually explode. So being able to treat and help koalas is few and far between because they're basically incinerated," she said.

The Wildlife Hospital will be working around the clock for weeks to come to give Australia's most vulnerable animals the best chance of survival.