Australia has had a love affair with brumbies since the days of Banjo Patterson, but the modern reality for the animals is far from the romance evoked in The Man From Snowy River.

Almost 40 brumbies have been found dead among one herd of heritage horses, prompting calls for intervention and better management of the animal's numbers in order to preserve the Australian icon.

Warning: This story has images that some readers may find distressing.

A brumby conservationist reported the dead horses on a recent trip to the remote northern end of the Guy Fawkes River National Park in the Northern Tablelands of New South Wales.

Erica Jessup from the Guy Fawkes Heritage Horse Foundation said she believed the drought and poor management were to blame.

"It's like a badly run horse stud; all it is is horses and cattle," Ms Jessup said.

"It's grazed to an absolute bare minimum. We've had a bit of a rain event, but it's a band-aid.

"Unless there's something done about the numbers in the northern end of the park this [brumbies dying] is going to happen every spring."

Erica Jessup (L) runs the Guy Fawkes Heritage Horse Association which rehomes brumbies. ( ABC Back Roads: Ron Ekkel )

Ms Jessup said she would like to see private contractors allowed into the northern areas of the park to trap the brumbies and bring their numbers down.

"The National Parks and Wildlife Service (NPWS) need help from the public to pressure the Government to give more time and funding to help with this program, because it's going to continue to be an animal welfare issue."

Should the brumbies live here?

Charles Sturt University ecologist, David Watson, believes brumbies have little to no place in national parks.

"The ideal number of wild horses is zero," Professor Watson said.

He has been a member of the NSW Government's Threatened Species Scientific Committee and advised the Government on managing threatened plants and animals across the state.

He resigned from the role in June when the Kosciuszko Wild Horse Heritage Bill 2018 was passed despite his committee advising against it.

The Bill gave protected status to feral horses in the Kosciusko National Park.

Professor Watson said while it would be near impossible to remove all the brumbies from Guy Fawkes River National Park due to the area's rugged terrain, their numbers should be reduced.

"We need to get it down to a point where the effects they're having are tolerable; and the data we've seen from [Victoria] show that even 100 animals in a large area still have measurable effects degrading the system," he said.

"The longer we leave this, the worse it gets."

This decaying brumby was found dead in Guy Fawkes River National Park. ( Supplied: Guy Fawkes Heritage Horse Foundation )

Conservation favoured

The Guy Fawkes Heritage Horse Association rehomes brumbies captured each year in a passive trapping program run by the NPWS.

The Association was founded by locals in response to the aerial cull of 600 horses in the Guy Fawkes River National Park in 2000, a situation the Association does not want to see repeated.

This year the Association has received 102 horses, but Ms Jessup said it should be more.

"It's a good number, but it's probably 500 short of what the breeding rate is," she said.

"The population expands by 20 per cent each year, so they need to be removing more than that."

During Ms Jessup's trip to the northern end of the Park she counted in excess of 600 live horses and 37 dead.

"One mare had died foaling, two had trees fall on them, but the rest seemed to have died over the last couple of months to starvation," she said.

"The further north you go, the tighter conditions are and the less condition the horses are in."

Ms Jessup said NPSW's trapping program was working well in the southern and western areas of the Park, but the remote nature of the northern end of the Park meant it was harder, more time consuming and expensive to control numbers there.

Almost 40 dead brumbies were found recently in the Guy Fawkes River National Park. ( Supplied: Guy Fawkes Heritage Horse Foundation )

"It doesn't matter whether you're a horse lover or a tree lover, it's not a pleasant place to be in the northern end of the Guy Fawkes National Park."

Committed to management

The NPWS said it was currently considering options for updating population estimates in Guy Fawkes River National Park, and it was concentrating its capture program in the southern end of the reserve in an attempt to remove all horses from this area.

A spokesperson said the brumbies had not adapted to living in drought.

"The recent deaths were a result of a culmination of factors associated with a lack of feed," the spokesperson said.

"Where horses are in remote, inaccessible areas this can lead to compromised immune systems making horses susceptible to disease and parasites."

The spokesperson said trapping in the northern end of the park was challenging due to its geography.

"NSPW will be working with the Guy Fawkes River National Park horse management reference group on ongoing issues concerning horse populations in the park, with the aim of protecting the values of the park," they said.