Australia has a curious relationship with its wild horses.

In the Northern Territory and Western Australia, where the majority of the estimated 300,000 feral horses in Australia can be found, they are routinely shot from helicopters as part of aerial culling that also targets other introduced species such as pigs, buffalo and donkeys.

But in the high country straddling the border between New South Wales and Victoria, the wild horses are revered, embedded in folklore and Australian literary history, from Banjo Paterson’s poem The Man From Snowy River to Elyne Mitchell’s Silver Brumby children’s books.

This week, the New South Wales government scrapped a recommendation from its own environment department to cull brumby numbers in Kosciusko national park by up to 90% and instead introduced legislation to formally recognise their cultural and heritage significance and ensure they are protected as an ongoing part of the park’s landscape.

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The deputy premier, John Barilaro, whose electorate of Monaro includes the national park, said locals had been calling for the change for years.

“If we accept that the brumby has a right to exist in the Snowy Mountains region – a right that this bill encapsulates – and we recognise the brumby’s unique place in Australian history, then we must find ways to preserve a sustainable population in a way that minimises harm to the environment,” Barilaro told parliament.

It is the first time a government has ever mandated the protection of an invasive species within a national park, and conservationists say it establishes a worrying precedent.

“To keep horses in the national park is to essentially compromise the environmental values of the park,” Deakin University ecology professor Don Driscoll said.

Driscoll has been an outspoken critic of the move away from aerial culling of brumbies in the national parks, saying that population reduction was necessary and a well-performed cull was more effective and less cruel than other forms of population management.

“There is no effective way of managing them if they are not allowed to cull them,” he said. “If we enter a dry period or there is a large fire, thousands of horses are going to starve to death.”

The abandoned brumby control policy would have seen numbers decrease in Kosciuszko national park from the current population estimate of about 6,000 to a herd of about 600, a move that brumby advocates say would have essentially rendered this particular mob of wild horses – which have been breeding largely independently since the 1800s – extinct.

It also would have relied on aerial shooting, which despite its widespread use on feral horses in Australia’s interior faces heavy public opposition on the eastern seaboard. An aerial cull in Guy Fawkes national park near Armidale in northwestern NSW in 2000, in which 606 brumbies were killed, is frequently cited as an argument against culling because at least one horse was found alive with bullet wounds seven days later. An internal review found that horse was an outlier and there was “no evidence to support a claim that the horses had not been killed humanely.”

Instead of culling, numbers will be managed by trapping and rehoming programs, supported by a government marketing campaign to promote brumby adoption. The government has also said it will investigate fertility control options. The Australian Veterinary Association says fertility control is not currently a viable option because the injections given to mares only last a few years.

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Brumbies will also be moved on from more “sensitive” areas of the national park, a condition that Driscoll said falsely implied that other areas can withstand sustained environmental damage.

“There are no less sensitive areas,” he said.

Kosciuszko national park covers 6,900 square kilometres on the NSW side of the Australian alps and is contiguous with the Alpine national park, on the Victorian side of the border. It was declared a Unesco biosphere reserve in 1977 and is home to a significant number of threatened species, many of which, like the critically endangered northern and southern corroboree frog, are endemic to the park.

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In January, the NSW threatened species scientific committee recommended that habitat degradation caused by feral horses, particularly in Kosciuszko, be listed as a key threatening process in the state’s Biodiversity Conservation Act. A similar listing already exists in Victoria.

The committee cited damage to streams and fragile sphagnum bogs caused by the horses’ hard hooves, the spread of weeds and an overall change to the density and diversity of the woodland structure caused by horses ring-barking trees or nipping off buds.

This damage has been documented over a number of years by government scientists. But groups that lobby for the brumbies to remain, such as the Australian Brumby Alliance, say that because that data has not been published in a peer-reviewed scientific journal it should not be accepted as evidence of damage done by wild horses.

That is an argument that Driscoll refutes and which could soon expire. Two papers on the ecological impact of brumbies in the high country are slated for publication later this year.

Madison Young, the vice-president of the Australian Brumby Alliance, said existing evidence compiled by the Parks and Wildlife Service did not prove that brumbies damaged the environment and that more research should be done.

She also said research should be conducted to determine the ecological impact of removing the horses, suggesting the environment may have adapted to the presence of the horses.

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“People are getting very caught up in this idea of ‘what about the [native species]’, but what is the evidence that horses are doing anything to the natives?” Young said. “It goes back to this idea of a ‘feral animal’ and just because it’s a feral animal it should not necessarily be here.”

Similar arguments were used by overlapping interest groups in the debate on banning cattle grazing in the high country.

Young is involved in brumby rehoming programs and usually takes about 14 horses that have been trapped by authorities in the park each year. Once trained, she said, they make good children’s mounts.

She said lobbyists opposed all brumby culls, but that the Kosciuszko brumbies held a special place in the public consciousness, particularly among those from the settler families who formed the mountain cattlemen tradition. She added that the cultural and heritage roles of the wild horses could not be fulfilled by removing them from the national park but allowing them to remain in surrounding state forest.