As rangers re-entered Kosciuszko National Park after last week's devastating bushfire, they were shocked at the destruction of nature and history, which they say could take centuries to recover.

The Dunns Road fire tore through Batlow and into Kosciuszko National Park, decimating much of the landscape.

It also destroyed homes and killed Goulburn man David Harrison, who was defending a friend's property.

In the aftermath, stepping out into the blackened, smouldering landscape of Kosciuszko, the first thing to hit you is the smell of smoke.

Then, you are confronted by — of all things — wasps.

The bright yellow of protective gear, worn by firemen and cameramen alike, is the only colour remaining in the ashen high country.

Drawn to it, the insects cling to the suits and sting any skin not covered up.

Their vast habitat has been completely transformed by the massive blaze, but they are far from the only species affected.

Fate of wildlife largely unknown

Looking out across the bare plains of Kosciuszko, whirlwinds of ash dance along the darkened earth.

Rangers say it will be difficult for Kosciuszko's wildlife to find food after the fires. ( ABC News: Matt Roberts )

Wild horses seek out the dry patches of grass skipped over by the fire as it moved through.

Some wander the roads and dusty ground gingerly, with visible injuries to their hooves.

There are concerns for the surviving wildlife in the severely burned areas of the park, and how they will fare with little to feed on.

The high country is also home to endangered species like the southern corroboree frog and smoky mouse, whose fates are unknown.

Collectively, it is expected that over a billion animals and "hundreds of billions" of insects have been killed in the New South Wales bushfires this season.

Rangers prepared, but surprised

The NSW National Parks and Wildlife Service was prepared for this fire season, its senior officer Mick Pettitt said.

They knew it was dry, they knew it would be hot, and they knew there was enormous risk.

But the ferocity surprised them.

NPWS Southern Ranges director Mick Pettitt did not expect the fires to be so ferocious and to destroy so much. ( ABC News: Matt Roberts )

As Mr Pettitt re-entered the park yesterday and sifted through the debris he was quiet; shocked at how little remained.

"The fire intensity was amazing, it was just so huge," he said.

It is hard to estimate how much the two major fires still active within the Kosciuszko National Park have burnt, but it likely stretches into the hundreds of thousands of hectares.

Fire turned stone and steel to ash

The fire cut a wide path through the middle reaches of the alpine wilderness, consuming areas like Cabramurra, Talbingo Reservoir and the popular Selwyn Snow Resort.

Not a building was left standing at Selwyn Snow Resort. ( ABC News: Matt Roberts )

In the long-abandoned mining village of Kiandra, which has weathered bushfires before in its 140-year history, devastation is everywhere.

This summer has destroyed what remained of the gold rush town.

The old courthouse — also a bar, chalet and police station in its time — is in ruins; only its scorched bluestone walls still stand.

The area around it was bare except for short, dry grass, but that did not matter when the fire approached.

It was so hot the glass and aluminium in the window frames melted.

"We're really surprised that some of these buildings are actually gone," Mr Pettitt said.

"The intensity must have just been off the scale, to come through and burn this."

The long-abandoned village of Kiandra on the Snowy Mountains Highway has been destroyed. ( ABC News: Matt Roberts )

It was just one of many historic huts and shelters sprinkled throughout the mountain ranges lost to the fire.

Mr Pettitt said it is a loss to history.

"It's not just the financial impact, it is the emotional and physical work that has gone into this area," he said.

"And to see it lost … it's devastating."

Ancient ecosystems lost to the fires

Sawyers Hill hut was reconstructed after 2003 bushfires, only to again be destroyed. ( ABC News: Matt Roberts )

Like many Australian landscapes, the high country has felt fires before — parts of Kosciuszko were burned during the 2003 fires that eventually destroyed hundreds of Canberra homes.

But this time, the fire has reached into areas where it does not usually go, including sensitive bogs dried out by drought — even burning across bogs still filled with water.

Mr Pettitt said they were hugely important to the landscape, and the water catchment more broadly.

"They take centuries to grow properly, but they can recover," he said.

For now, however, recovery is not Mr Pettitt's primary concern; his attention is focused on where the fire might strike next. It is far from extinguished, and there are fears it may flare in some areas again in warmer, windier conditions.

The fire danger rating for today is severe in the Monaro Alpine, and extreme in the neighbouring Southern Slopes.

Jindabyne Streets are left empty as Kosciuszko National Park is evacuated due to the bushfire threat. ( Supplied: Cameron McKid )

Towns like Jindabyne and Thredbo were on tenterhooks during the worst of last weekend.

The main streets along both towns are quiet, with Thredbo near empty during what is usually a busy summer tourist season.

But, as it has before, recovery will come, and those who love the area most will be there to see it through.