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In battle of the brumbies, AI may bring new firepower to surveys, but a long way to go, experts say

For decades, Australia’s high country has been the scene of a fierce flashpoint in the management of invasive species. Disputes around the science of surveying wild horse numbers have prompted experts to urge more collaboration between champions of the fragile alpine environment and the pro-brumby brigade. Harshita Roy kicks off our special series on invasive species, Gone Feral.

In battle of the brumbies, AI may bring new firepower to surveys, but a long way to go, experts say

A wild horse in Kosciuszko National Park, where aerial culling is being carried out. Experts say AI-assisted methodology has promising potential for surveying horse numbers, but argue that interpretation of an aerial survey commissioned by brumby advocates was seriously flawed. Photo: Shutterstock

Story by Harshita Roy
 

A privately commissioned survey enlisting artificial intelligence tools which claims to show that officials have significantly overestimated feral horse numbers in Kosciuszko National Park has been dismissed by ecologists, with one describing it as “technically excellent” but “ecologically useless”.

Retired senior ACT Government ecologist Dr Don Fletcher also described the $78,000 “independent wild horse recount” – commissioned and crowd-funded by brumby defenders – as a complete waste of donations.

The management and culling of feral horses throughout high country national parks has driven fierce divisions for decades, with tensions escalating in recent years into what’s widely described as a culture war conflict between brumby defenders and people concerned about their documented impacts on the fragile alpine environment and threatened native species.

The latest legal skirmish played out in the New South Wales Supreme Court this week when a judge dismissed an attempt to stop the aerial shooting of brumbies in Kosciuszko National Park, rejecting arguments brought by pro-brumby advocates that the NSW environment minister did not have adequate information when she authorised the method in 2023.

Both sides have enlisted scientific arguments to back their cases over the years, including on the central question of the population of wild horses. Earlier this year, an aerial survey commissioned by pro-brumby advocates enlisting artificial intelligence tools was released, which they claimed provided evidence that officials have significantly overestimated feral horse numbers in Kosciuszko National Park.

Ecologist and feral horse specialist Dr David Berman, pictured in Victoria’s Bogong High Plains, urges more cooperation to bridge the trust deficit between environment and horses advocates. Photo: Supplied

Ecologist and feral horse specialist Dr David Berman, pictured in Victoria’s Bogong High Plains, urges more cooperation to bridge the trust deficit between environment and horses advocates. Photo: Supplied

The survey found just 569 horses in a 21,200 hectare section in the north of the park – about three per cent of its total area. According to survey organiser, Rocky Harvey, the count would likely be over 5000, based on his estimates applying data from the NSW National Parks and Wildlife Service 2023 survey.

But Fletcher and fellow ecologist Dr David Berman of the University of Southern Queensland, say the independently commissioned aerial survey is seriously flawed.

They say, for example, it did not include a formula to estimate the number of horses likely to be present but not seen or counted. Nor did it include an estimate of the proportion of the horse population in the survey.

Berman added that he believed the AI-assisted methodology had promising potential, urging further testing and development to better track horse numbers in the future. He recommended incorporating thermal imaging. By trialling it in a contained area with a known horse population, it could provide a formula to estimate the number of horses the model doesn’t detect.

Conducted by Airborne Logic, a remote sensing agriculture and environment consultancy based in Adelaide, the survey used high-resolution aerial images taken from a low-flying aircraft to stitch together an orthophoto map, smoothing out terrain and camera distortions. An object detection tool, based on machine learning, was then trained to scan the image and identify horses. Airborne Logic referred all questions about the methodology to organiser Harvey.

According to Dr Don Fletcher, the aerial imagery made available by Airborne Logic shows horse damage such as roll pits, trampled creek and horse tracks. Image: Airborne Logic (Available for public use)

According to Dr Don Fletcher, the aerial imagery made available by Airborne Logic shows horse damage such as roll pits, trampled creek and horse tracks. Image: Airborne Logic (Available for public use)

The private survey was commissioned and crowdfunded as “an independent count of wild horses in the Kosciusko National Park” by Harvey – a builder and butcher from Jindabyne – and Macquarie University bio-statistician Claire Galea. On their “gofundme” page, they argue that better, more accurate techniques are required to resolve widespread “dispute on actual wild horse numbers in the park”.

Galea declined to respond to questions, other than to say she was no longer involved in anything to do with the wild horses due to “threats and harassment”.

While the survey report includes a peer review by an independent AI expert, this is confined to the technology and its application and doesn’t explore the ecological component.

“The plan to use this technology and the interpretation of its result were done by cull protestors. None of that was peer-reviewed,” says Fletcher, who is a threatened species management expert who remains actively involved in the NSW Senate inquiry on feral horses, including making several written submissions. In July, he published a detailed critique of the aerial survey online.

The AI method was developed to challenge the established, widely-used distance sampling methodology used by the NSW Government to estimate wild horse numbers. This survey, conducted by ecologist Dr Stuart Cairns of the University of New England, collects observations from a pair of specialist observers flying at low altitude over the area, seated each side of the aircraft and recording sightings of horses and related data, such as the distance of the animal or cluster from the observer, habitat cover and cloud cover.  No horses are photographed or described.

Independent horse count organiser Rocky Harvey says he is convinced machine learning will be used to count wildlife in the not-too-distant future. Photo: Supplied

Independent horse count organiser Rocky Harvey says he is convinced machine learning will be used to count wildlife in the not-too-distant future. Photo: Supplied

These are then analysed “using advanced software to reliably estimate the wild horse population in the entire survey area”, says the NSW National Parks and Wildlife Service, and peer-reviewed by independent experts from CSIRO and the Queensland Department of Agriculture and Fisheries.

The distance sampling method applies a derived mathematical formula to estimate the number of horses that are present but not seen, which the Airborne Logic method lacks, says Berman, who also works for Queensland Forestry with contractor HQPlantations and The Brumby Project to manage and rehome feral horses.

Co-organiser Rocky Harvey argues that the number of horses not seen are “absurd” and vastly overestimate the true numbers.

“What we set out to do was to demonstrate to government that there are better ways to do it,” says Harvey, echoing the view of many in the pro-bumby community that the parks service is not using the best available science to count wildlife.

Last year, Harvey dumped a dead horse’s head outside the national parks office in Jindabyne to bring attention to the mass culling of feral horses and their improper carcass disposal.

Ecologist Berman urges more cooperation to bridge the trust deficit between the two sides. “National Parks, they get sick of being attacked and do not provide enough information, and the other side then gets upset and attacks more.”

He suggests engaging the concerned community groups in research. “You have got to gain trust with the community … You’ve got to get them as part of the team working on this problem.

 “So Rocky Harvey needs to be in there working with the rangers to solve this problem.”

Recent data released by the NSW government has revealed that 8,944 feral horses have been removed from Kosciuszko since 2021. Of these 5963 were aerially culled.

The NSW government plans to bring down the feral horse population in Kosciuszko from 17,393 estimated in November 2023 to 3000 by 2027, using various lethal and non-lethal control methods.

This story is co-published with Cosmos online – ‘The Science of Everything’

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