I read with concern the article ‘Why do we kill wild horses’ by Dorothy Hatzopoulos as it fails to give a true picture of feral horse management in national parks.

In her article, Dorothy Hatzopoulos notes the important place of horses since ancient times in the arts, literature and poetry of Greece and other countries. But horses in the arts, literature and poetry do no damage. Horses on the ground can do quite a lot of damage. In Australia, where the environment has evolved in the absence of horses, they can do a great deal of damage. In our national parks feral horses (known as brumbies) push native plants and animals towards extinction. We Australians, old and new, have a responsibility to care for the unique environment in which we now live.

It may not be a comfortable decision, but this care extends to supporting government efforts to control horse numbers in national parks. National parks should be parks, not paddocks. The purpose of the Kosciuszko National Park is to protect the natural landscape, its waters, its sphagnum bogs, its native fish, its corroboree frogs, its alpine orchids, native daisies, pygmy possums – all the plants and animals that were here before the First Fleet arrived in 1788. National parks are not set up to protect introduced weeds, and certainly not to protect the animal species brought to Australia in the last 235 years and allowed to run wild, such as feral pigs, goats, deer and horses.

The damage done by feral horses

Dorothy Hatzopoulos wants feral horses to be protected in national parks. She asks “Since when has this magnificent animal been ‘validated’ as a nature killer and environmental destroyer?” The answer is, for at least 80 years in new South Wales. From the 1940s scientists like Alec Costin were seeking the end to all grazing in alpine national parks. In 1957, the view of the Australian Academy of Science was that “the aim to be achieved as soon as possible is the complete exclusion of all grazing animals from these important catchments at heights above 4,500 feet”.

If Ms Hatzopoulos is seeking “validation” of the impacts of feral horses in alpine national parks, there are hundreds of studies available. They show that feral horses increase sediment in subalpine streams, act as reservoirs for disease, trample down the vegetation that corroboree frogs need to breed, graze down the grass cover that native broad toothed rats need as protection from predators and from the winter cold, and trample the burrows of native crayfish.

A Senate Inquiry into Impacts and Management of Feral Horses in the Australian Alps confirmed on the evidence presented to it that “feral horses are destroying vital habitat and food sources for critically endangered, endangered and vulnerable species protected at the Commonwealth and state levels”. It found that “Waterways, which not only provide vital habitat for the critically endangered corroboree frogs and threatened plant species but also provide drinking water into our catchments, are degraded by the hard hooves of feral horses.”

A tarn (pond) on the Kosciuszko Main Range in a natural condition. Photo: Supplied

How many feral horses?

Dorothy Hatzopoulos states in her article that feral horse population estimates are ‘innacurate’ but provides no evidence to support this claim. Estimating the abundance of animals is a difficult aspect of ecology. The method used for counts in the alpine national parks is well-known and tested and is called ‘Distance Sampling’. The ‘sampling’ in its title refers to the fact that only a proportion of the site is actually inspected. That is because the counting helicopter flies along straight, east-west lines spaced far enough apart so that horses counted on one transect cannot be counted again on the next one. Distance Sampling has become one of the most widely used methods of counting animals in national parks and reserves. There are thousands of peer-reviewed scientific papers that support its use. Populations of a wide range of species have been reliably estimated using Distance Sampling, including fish, reptiles, antelopes, deer, kangaroos, feral pigs, fruit bats, primates, polar bears, whales and dolphins.

Ms Hatzopoulos states quite wrongly in her article that after the 2019 survey, “state governments have been repeatedly asked to do a new count, pleas that have been ignored systematically for years”. In fact, surveys of horses in Kosciuszko National Park have been done in October every year since 2019, although not in 2021 when bushfire recovery work took precedence.

Her article makes the absurd claim that “the majority of brumbies live in the alpine zone of Australia”. The highest official estimate of feral horses in the alpine zone was 25,318 in 2019. The federal Department of Environment has reported that Australia has an estimated 400,000 feral horses, mainly in central and northern Australia. Only about 6% of Australia’s feral horse (brumby) population is found in the alpine zone.

The feral horse population at Kosciuszko according to brumby advocates is very low: no more than 3000. This number is not based on a scientifically controlled count, and is not credible. At the end of January 2024, the number of feral horses removed from Kosciuszko since 2021 by re-homing, transport to knackeries, or in-park shooting was reported by the NPWS to be 3530. This is more than the 3000 population claimed by some brumby advocates and, as shown in a photo accompanying this article taken in late January 2024, there are still plenty of feral horses in the Park.

Erosion in Little Peppercorn Creek, Kosciuszko National Park, caused by feral horses grazing upstream. Photo: Linda Groom

Is aerial shooting inhumane?

Mustering and trapping feral horses is not an effective (or even humane) method of reducing the feral horse herd at Kosciuszko. As most cannot be rehomed their suffering is extended for no good purpose. If the numbers are to be reduced there is no alternative to ground and aerial shooting.

In 2023 the NSW government asked two independent veterinarians and the RSPCA if aerial shooting from a helicopter is humane. The government gave them free access to observe aerial shooting of horses at Kosciuszko. Their reports stated that the shooting program met all animal welfare requirements.

The reports noted that an average of 7.5 shots were fired at each horse. The first and second of these shots was intended to kill the horse, or make it insensible. As it is difficult to tell from a helicopter whether a horse that is lying still on the ground is dead or just unconscious, the procedure requires the shooter to take several more shots at the dead or unconscious horse. A skilled pilot can get the helicopter to within 20 metres of the target, and can match the speed of a moving horse. The whole procedure reflects a strong determination to minimise any suffering.

Could fertility control be the answer?

As part of her PhD with the University of Technology Sydney, veterinary specialist and brumby re-homer Dr Andrea Harvey trialled the GnRH immunocontraceptive on Australian feral horses. She reported that darting with GnRH was not effective: “Unfortunately in short the answer to the question, ‘Will it prevent mares having foals?’ was no,” she said. “Over 50 per cent of the mares in this pilot study, which was 10 out of 19 mares, did have foals”.

The study took place at the Save the Brumbies Sanctuary, New England, with presumably easier access for the darting team than in a national park. Dr Harvey has described the reasons for the outcome of the trial: “In other parts of the world where dart administration of immunocontraceptives has been successful, they have been applied to horses that are used to people, allowing staff to approach horses on foot. This is a very different situation to Kosciuszko National Park … Furthermore, it would be close to impossible to both identify and locate the same horses on multiple occasions, as required for booster vaccination injections. In more densely forested areas, it can be challenging to even see horses, let alone dart them”.

Fence in Kosciuszko National Park separating area on left grazed by horses, from area on right where horses have been excluded. Photo: Supplied

What do the Indigenous people think of this issue?

Dorothy Hatzopoulos states in her article that there is, “significant demand for the protection and conservation of wild Brumbies, including from Indigenous Australians” The findings of a NSW government report on ‘Aboriginal people’s associations with wild horses in Kosciuszko National Park’ do not support the claim that there is a demand for conservation of feral horses in the Park among indigenous Australians.


At the last count, feral horse numbers in Australia’s Alpine zone were about 25,000 and increasing. The environmental impact of these large, heavy, hard-hoofed animals is substantial. The problem must be managed and until an effective and economical method of fertility control, or some other alternative, is developed, ground and aerial shooting must be part of the response.

*Peter Prineas OAM is a former director of the National Parks Association of NSW and served on the NSW National Parks and Wildlife Advisory Council and the board of the NSW Environment Protection Authority.