Park rangers shooting brumbies from helicopters are being harassed and threatened as union leaders call on politicians to take the heat out of the debate over controlling the feral animals.
People opposed to aerial culling of brumbies have been left distressed by the population control measure and have called for a collaborative approach and new methods.
The NSW government in October announced the state would return to aerial shooting of brumbies in Kosciuszko National Park to control burgeoning numbers.
Feral horse numbers have exploded since former NSW Nationals leader and deputy premier John Barilaro opposed culls in favour of trapping and rehoming in 2018.
The state has legislated to cut the population to 3000 by mid-2027, but officials estimate up to 22,500 horses are in the park.
Since aerial culling restarted, National Parks and Wildlife Service rangers have faced increasing hostility from members of the public opposed to the plan, a union told a parliamentary committee examining the government's decision.
Public Service Association of NSW assistant general secretary Troy Wright said members including park rangers conducting culls faced increasing harassment and threats and the "heat and emotion" needed to come out of the debate.
"(Culling) is in essence ... an ecological (decision) driven by the fragile best interests of the park and the natural environment," he said on Monday.
"Our members as public-sector workers may hold views in favour of the current approach based on their experience, however they do not hold sway over which decision is implemented and they should not be made into public pariahs for doing so."
Environmentalists argue feral horses are changing the landscape significantly, impacting native animal habitat and important waterways.
Heritage Horse and Environment Alliance convenor Jill Brown said brumby advocates were positioned as "lunatic" anti-conservationists.
Advocates were left distressed by the culls and some had pulled back for mental health reasons, but Dr Brown said she was not aware of threats or aggression towards workers on either side.
"I am aware that every time this conversation comes up people who are pro-culling start talking about how staff members are threatened and how aggressive and unpleasant we are," she said.
Dr Brown criticised the government not trialling fertility controls and commencing aerial shooting before the inquiry reported.
"I'm appalled by the fact that they've set up an inquiry and then, to all practical purposes, are ignoring the inquiry … because they're busy killing horses," she said.
Mr Wright said feral animal control was undertaken with pigs, camels, cats, goats and foxes to protect native ecosystems, yet only the horses attracted such high levels of public interest.
"The hypocrisy is that there is concern about the brumbies but not concern about the species that they threaten ... and our members are surprised by the weighting that appears to be given to different species," he said.
"It's either Kosciuszko National Park or brumbies, we cannot have both."
Dr Brown said extreme ends of the debate would not bring a solution.
"I would like to assume it's the same on the other side and that we're all motivated to find the best possible humane, effective, ongoing solution," she said.
Other horse advocates said the heritage value of brumbies in Australian culture is being ignored.
They also rejected horse number estimates, arguing the environmental toll on the park is being caused by other feral animals and humans.
Leisa Caldwell, a former member of the Kosciuszko National Park wild horse community advisory panel, told the committee the numbers were "biologically impossible".
