A bitter feud has broken out in NSW's Snowy Mountains over the fate of Australia's iconic brumbies, pitting activists, locals and scientists against one another. 

Thousands of brumbies, which have roamed the Snowy Mountains for more than 200 years, are set to be shot from helicopters as part of a controversial month-long cull in Kosciuszko National Park that began on Monday.

The operation is funded by the NSW Government and managed by the NSW National Parks and Wildlife Service, which aims to reduce the park's wild horse population from more than 10,000 to 3,000 by mid-2027.

The usually quiet town of Jindabyne has become the epicentre of the dispute, with emotions running high and fears that some activists could take their opposition to the brumby cull too far.

Among those caught in the crossfire is Professor David Watson, an outspoken advocate for feral horse control, who says he is now receiving death threats over his stance.

'Jindabyne is a very polarised community because of the really antisocial, and often illegal, behaviour of these feral horse advocates.

'They've come out in recent days and said they'd be shining lasers into the eyes of helicopter pilots doing their job.

'They think the laws don't apply to them, they tamper with traps and with cameras set to monitor numbers. This is not a level playing field,' Professor Watson said.

Professor Watson said while brumbies consume large amounts of vegetation, the greatest environmental damage comes from their movement across fragile alpine landscapes.

'The soil is very shallow and weathered, and there are quite delicate wetland systems with mosses that, once they're compressed, die,' he said.

He urged opponents of the cull to consider the scientific evidence.

'Humans have such a long shared history with horses and we care about them, so any discussion about controlling them, let alone killing them, is a very tough discussion for people to have,' he said.

'Effectively, that's a valued position about what we care about more – do we care about horses more than all of the natural and cultural heritage values that led to that little part of Australia being designated as a national park in the first place?

'It's an easy decision: I've got two horses on my property and if I want to see them, I can go out my back door and pat them.

'If I want to go and see these beautiful wilderness areas, I don't want to go there and see it being smashed by this barnyard animal that's found worldwide.

'In Kosciuszko, you've got tens of thousands of years of history on the rooftop of Australia and the largest native animal wandering around there is the eastern grey kangaroo at around 70 kilos.

'We're now talking about animals that are 10 times that size and they don't have flat furry feet, they have hooves. The high country has never seen an animal of that size before, so the soil, the plants, the whole ecosystem have never had to deal with that.'

But many opponents remain unconvinced, with some activists encouraging others to  name and shame the pilots and helicopter companies involved in the brumby shooting operation.

Others have threatened to enter closed sections of the national park to try to disrupt the shooting operation as debate over the cull intensifies on social media.

Animal welfare campaigner Julie Kernich, who has been camping near Mount Kosciuszko in protest against the cull, issued a public plea for the NSW Government to stop the operation.

'We're not saying there's no problem with the environment, what we're saying is stop the cull for now, please,' Ms Kernich said.

'Work with your citizens, there are groups that are willing to help rehome and desex these beautiful animal, instead of murdering them and making it the snowy bloody river.'

Cooma Mountain Brumby Sanctuary founder Gabriela Black described the operation as 'completely barbaric' and said the government was targeting the wrong source of environmental damage.

'It is so inhumane to shoot these horses from the air, leaving them to die slowly and painfully,' Ms Black said.

'The destruction of the national park is from the Snowy Hydro project, not these beautiful horses.'

Ballistics expert Andy Mallen, a longtime member of Australian Hunters International, said the brumby cull was an example of the 'hard left at work'.

'They're trying to remove another symbol of Australian culture. It's, it's an iconic symbol of our, of our culture,' he told 2SM.

Mr Mallen also questioned whether aerial shooting was humane, pointing to trial data that showed the 270 horses killed required an average of seven and a half shots each, with one animal reportedly needing up to 15 bullets before it died.

'No one argues that horse populations should never be controlled. Any animal population needs to be managed if numbers exceed the carrying capacity of the land.

'We shoot millions of kangaroos across eastern Australia every year to keep their numbers under control. We're familiar with the process and we know how to do it. But there is an SOP for kangaroos requiring that they only be shot in the brain because that is considered humane.'

A petition opposing the operation has attracted about 220,000 signatures, while thousands online have called for the cull to be halted.

'Those brumbies are not feral animals, the only ferals are the idiots behind the rifles,' one activist said.

Another said: 'No marksman, no matter how skilled, can completely eliminate the risk of wounding when shooting live animals from a moving helicopter across rugged terrain.

'A shot that strikes a leg, neck, shoulder or abdomen can leave an animal injured rather than dead. Those who survive such wounds may face prolonged suffering from pain, blood loss, infection, exhaustion or starvation.'

A third said: 'If you shot a racehorse or a domestic horse in this country you'd be charged with animal cruelty faster than you could blink. But somehow the same animal, living wild and free in the mountains, can be chased by a helicopter and shot from the sky and that's called management.'

But the NSW National Parks and Wildlife Service maintains horse numbers remain unsustainably high despite years of control measures.

'While there are early signs of groundcover and vegetation recovery in areas where horse numbers have been reduced, numbers remain high and the damage wild horses cause remains evident across many parts of the park,' a spokesperson said.

The NSW Government last month announced a trial of fertility control for wild horses in the Snowy Mountains.