While speaking to the NSW parliament in December, an ecologist expressed fears that the number of koala deaths may never be known.

"The fires have burned so hot and so fast that there has been significant mortality of animals in the trees, but there is such a big area now that is still on fire and still burning that we will probably never find the bodies," Nature Conservation Council ecologist Mark Graham said.

Science for Wildlife executive director Dr Kellie Leigh also told the hearing that koala populations threatened by bushfires have no resources or planning in place to save them.

"We're getting a lot of lessons out of this and it's just showing how unprepared we are," Dr Leigh said.

"There's no procedures or protocols in place - even wildlife carers don't have protocols for when they can go in after fire."

The Sydney Morning Herald reported that experts believe human intervention is needed to repopulate sensitive species that would otherwise be wiped out locally.

Wildlife Rescue South Coast secretary Jenny Packwood said there is a "starvation event" after flying foxes flew south in spring after fires destroyed their habitat.

"Mothers are abandoning babies at two weeks after birth because there is no food for them. We've picked them up out of local colonies," she said.

"Last week we had 300 come in and we've been flat out feeding since then. We had to fly some of them to the North Coast, to carer groups up there."

University of Sydney professor of conservation biology Mike Letnic said droughts and fires will put animals under pressure this summer.

"With the climate being so dry at the moment and the intensity of these fires, wet gully areas and so on that normally escape the worst of it have been burnt," he explained.

Letnic added that animals who often survive in unburned patches can recolonise, but believes there may not be enough pathways for "effective" recolonisation.

The bushfires have devastated the country since September and have reportedly torn through nearly nearly five million hectares of land.