The rainforests along the spine of the Great Dividing Range, between the Hunter River and southern Queensland, are remnants of Gondwana, the ancient supercontinent that broke up about 180 million years ago.

"Listening to the dawn chorus in these forests is literally an acoustic window back in time," ecologist Mark Graham tells RN's Saturday Extra.

"It's like listening to what the world sounded like in the time of the dinosaurs."

The forests are mountaintop islands that have been "permanently wet" for tens of millions of years.

But now, some of these forests are being burnt for the first time.

These ancient rainforest environments have very little tolerance to fire. ( Facebook: Mark Graham )

"We are seeing fire going into these areas where fire is simply not meant to go," says Mr Graham, a fire specialist with the Nature Conservation Council.

Most of the focus of Australia's catastrophic fires has been on people and property — with the exception of koalas, which have come to symbolise the non-human costs.

Beyond the koalas are many rare and fascinating creatures whose lives and homes have been destroyed, or remain threatened.

"The fauna in these landscapes requires permanently wet conditions, and many of the fauna species in these landscapes simply have no tolerance to fire," Mr Graham says.

The most ancient birds on the planet

The songbirds that live in these ancient wet forests have always lived there.

Birdwatchers often visit the area to see birds like the Tree Creeper. ( Supplied: David Milledge )

The Albert's Lyre Bird. The Rufous Scrub Bird. The Log Runner. The Tree Creeper. And, confusingly, the Cat Bird; a large, green rainforest bird that wails like a cat.

They are internationally renowned. Birders from around the world come to see and hear them.

"These are global strongholds of the most ancient birds on the planet," Mr Graham says.

"All the birdsong around the world goes back to these birds."

Much of the land lost in the northern NSW fires is home to songbirds. ( Supplied: Peter Knock )

Since early September, when fires first started burning in the northern New South Wales, up to 2 million hectares of land have been lost, much of it forest, and much of it home to songbirds.

The losses cannot be assessed until the fires stop burning.

An enchanting little frog

The ancient, two-centimetre-long pouched frog is not the prettiest of rainforest frogs.

Motley brown and lumpy, it's so small and camouflaged in leaf litter that it is rarely seen or photographed.

Its reproduction is unique, and enchanting.

The pouched frog is rarely seen or photographed. ( Supplied: Murray Lord )

Also known as the hip-pocket frog, or the marsupial frog, the male has a pouch on either side of its body. The female lays her eggs on damp leaf litter. When the white tadpoles hatch, they wriggle into the male's pouches, and remain there for a couple of months, until they emerge as frogs.

Mr Graham says the pouched frog is one of the most vulnerable species.

"It requires permanently moist conditions and protection from fire. It's so small and delicate that fire wipes it out," he says.

Sorry, this audio has expired Hear more from Mark Graham on the devastating impact of the fires

It lives only in the mountains between Dorrigo and south-east Queensland.

The southern-most colonies, at Mt Hyland, near Mt Dorrigo, were burnt in September.

One of the biggest populations was in areas burnt earlier this month, in the Nightcap Range, north of Lismore and west of Byron Bay.

Terania Creek, in that region, was the famous site of the first forest blockade in the world, in 1979.

Data has been collected on the density of frogs in the Terania Creek basin since the late 1970s. It's not yet known how many have been killed.

A truffle-eating potoroo

For about 20 years, Mr Graham has worked on a project south of Ballina with the Jali Aboriginal community.

Part of the Bundjalung Nation, the community manages the Ngunya Jargoon Indigenous Protected Area.

It has, or had, Australia's biggest colony of northern long-nosed potoroos, which, at about 80 centimetre long, have a koala-like fluffy cuteness, like stuffed toys that move.

This particular potoroo lives in dry forests on the coastal plains next to the rainforests. It has a gourmet diet, digging up eucalypt truffles.

Many potoroos are believed to have perished in the recent fires. ( Supplied: David Milledge )

It turns out Australia has the world's greatest diversity of truffles — in the roots of our eucalypts.

The fungi that produce the truffles keep the eucalypts healthy. The potoroos eat the truffles, and spread the fungi through their poo.

"They are a keystone species, keeping the whole landscape together and healthy," Mr Graham says.

Thus the project with the Jali conservation managers.

"Together we've done lots of good work to understand how many numbers there are, and how and where they live, and to control foxes and predators," Mr Graham says.

Almost the entire area has now been burnt.

The fires swept through potoroo habitat, and it will take some time before rangers know how the animals fared. ( Supplied: David Milledge )

''The fires were so hot, particularly on two ferocious days of fire weather, it's likely that a lot of potoroos were killed," Mr Graham says.

"Those that survived have very little shelter, and are vulnerable to being eaten by foxes and cats."

Devastating losses

Mark Graham (L), pictured with his friend Chris Goode, started fighting fires in the area in September. ( Supplied: Mark Graham )

Mr Graham has been fighting the fires in the forests since they began about three months ago.

He, and dozens of likeminded people, have managed to save some of the old growth trees by clearing around them.

One reason the north coast of New South Wales is a global biodiversity hotspot is it has the most species of eucalypts in the world, and the best areas of Antarctic Beech forest.

"These forests are recognised globally for their outstanding universal values because they are essentially the oldest forests remaining on the planet," Mr Graham says.

The tree hollows host many fauna species, for shelter and breeding. The hollows take centuries to develop to full size. They can't be replaced.

"You have to wait 200 to 400 years until they develop again," Mr Graham says.

Mr Graham speaks in a calm, measured tone.

His fires losses have been deeply personal.

Visibility has been down to 200 metres at times during the fires, Mr Graham says. ( Supplied: Mark Graham )

One of two nature conservation areas he privately owns, and manages for their natural values, has been almost obliterated by fire.

He wants to present only the facts, and avoid fuelling a media and political circus around the fires.

But the marathon toll of anxiety, threat and loss is exhausting, as evidenced by a recent post he made on Facebook, at 2.30am:

"Friends. Shit is getting well-serious. "I am at my place at the very top of the Bellinger Valley. Smoke has completely saturated everything for days now. "Most of this evening I have heard the wind absolutely roaring on the escarpment above. These beasts are inexorably heading for Point Lookout and New England National Park — the biggest and healthiest chunk of Gondwana. "There are no words that can describe the significance, enormity and horror of what now looks highly likely to happen … Rain, RAIN … RAIN …"