Feral Deer Could Become Australia's Next Pig Problem, Unpublished Report Warns

A government report that was never made public has put a number and a grade on something land managers across Australia have been watching for years: feral deer are spreading, and almost nowhere is the country keeping up. The document, a national vertebrate pest management report card produced by the National Vertebrate Pest Coordinators, assesses the five years from 2020 to 2025 under the national feral deer action plan. It was leaked to the Invasive Species Council.

The report describes deer as one of the country's most rapidly increasing invasive pests. They have grown in number and in range, and it puts the cost at more than $91m every year in lost production and management time. Over the same period the animals, famously elusive, have pushed closer to major cities. Encounters have become more frequent, among them one in which two men in various states of undress were fined after getting lost in the bush, spooked by deer while nude sunbathing.

Six species of feral deer are established in Australia: chital, fallow, hog, red, rusa and sambar. Populations are well established across the south-east, where densities are highest, with smaller and more localised groups in South Australia, Western Australia and the Northern Territory.

The report card uses a traffic-light system across four categories, and the results are lopsided. New South Wales and Tasmania received reds in all four. Queensland and the ACT each got three reds and a yellow. Only one jurisdiction earned a single green: South Australia, which launched an ambitious statewide eradication plan in 2022 and was rated green in all four categories. The report found, with high confidence, that the state had reduced deer abundance, distribution, and their environmental and agricultural impacts.

Prof Euan Ritchie of Deakin University, president of the Australian Mammal Society, said he was not at all surprised. In his reading, governments are failing miserably to invest enough to control deer, whose effects reach agriculture, native wildlife, the environment, road safety and culturally significant sites. "This is what sustained failure to act sufficiently results in," he said.

Reece Pianta, advocacy manager at the Invasive Species Council, said the findings confirm what land managers have seen on the ground, and he pointed to long-term systemic underfunding of deer control. In May 2025 the council released footage and images that it said showed the Gold Coast under feral deer siege. Deer, he argued, lack the notoriety of other invasives but are just as necessary to control. "Deer are the next feral pig," he said, adding that the difference is that acting now could meaningfully change population numbers and contain, or even reverse, the spread. He said deer probably cannot be eradicated from the whole continent, but South Australia's top score shows eradication is possible in some states and territories, while others will need a long-term effort to contain them and limit harm.

Prof Andrew Lowe, director of the Adelaide University Environment Institute and a member of the Hills and Fleurieu Landscape Board, called the report a good news story for his state that matched what he sees. South Australia began tackling its deer problem in earnest in 2022, after an agricultural impact estimate showed annual damage of $36m was on course to reach $241m by 2031. Since a $4m eradication program began, he said, deer numbers have massively declined.

The job is not finished. Lowe said surviving deer are taking refuge on the fringes of urban areas, where culling costs more. He estimated functional eradication in South Australia would take about another $10m over 10 years. Without it, he said, the population will rebound. "So $10m versus $240m – do the math."

What to watch is whether other states, now graded red, move toward South Australia's model, and whether the urban-fringe refuges prove the hardest part of that model to finish.