A newly published Australian scientific paper detailing the eradication of invasive rusa deer from Queensland’s Wild Duck Island provides an important reality check for the increasingly common political rhetoric around “eradicating” wild deer populations.
The study, published in Biological Invasions in 2026, documents what researchers describe as the first successful eradication of an established rusa deer population anywhere in the world.
But far from proving that deer eradication is simple or scalable, the paper demonstrates the exact opposite.
The key lesson is stark: even on a tiny, isolated island where reinvasion was effectively impossible, eradication still took years, helicopters, thermal imaging technology, intensive camera trapping, specialist crews and enormous expense.
On the Australian mainland, with millions of hectares of connected habitat and highly mobile deer populations, eradication is not a realistic policy objective.
A Tiny Island. No Immigration. Six Years. Massive Cost.
Wild Duck Island is just 380 hectares in size.
Critically, it met the single biggest requirement for eradication success: no meaningful risk of new deer arriving.
Researchers explicitly noted that eradication was considered feasible because the island’s strong tidal currents and isolation made reinvasion highly unlikely.
In other words, this was close to an ideal eradication scenario.
Yet despite that:
- Initial control efforts from 2007 to 2017 failed
- A dedicated eradication campaign still took six years from 2018 to 2023
- 168 deer had to be culled
- Operations required helicopters, thermal imaging systems, specialist operators and dense camera-trap grids
- Aircraft costs alone exceeded AUD $175,000, excluding shooters, ammunition and substantial monitoring costs
And even after years of effort, the final surviving deer evaded conventional aerial shooting for 7.6 hours before eventually being located with advanced thermal imaging technology and culled after another targeted operation.
That was on an island smaller than many Victorian farms.
The Last Few Deer Were the Hardest
One of the most important findings in the paper is that the closer managers got to “eradication”, the harder and more expensive the task became.
Researchers noted that as deer numbers declined, “the hours flown per deer culled increased.”
The final remaining female deer was detected only twice across 5,400 camera trap days.
To finally confirm eradication, researchers then deployed 52 cameras for 4,094 trap days without recording another deer.
Even then, the scientists could only state there was a 99.3% probability of eradication.
The study repeatedly emphasises how difficult deer eradication is globally.
Of 408 island ungulate eradication attempts worldwide, only 27 involved deer species, and fewer than half were successful.
The authors bluntly state:
“Less than half of the eradication attempts for cervids on islands have been successful… demonstrating how difficult deer populations can be to eradicate.”
Mainland Australia Is a Completely Different Challenge
This is where the implications for mainland deer policy become unavoidable.
Wild Duck Island had:
- Fixed boundaries
- No roads
- No human habitation
- No hunting pressure from the public
- No meaningful immigration
- A population confined to 380 hectares
Mainland Australia has none of those advantages.
Victoria alone contains millions of hectares of connected deer habitat across public and private land. Deer move freely across landscapes, rivers, farms, forests and alpine terrain. Populations are continuously replenished through natural dispersal.
Even the scientific criteria for eradication outlined in the paper effectively acknowledge why mainland eradication is unrealistic.
The study cites the classic eradication requirements established by Bomford and O’Brien, including:
- Removal exceeding population growth
- Zero immigration
- Every reproductive animal being vulnerable to control methods
That second criterion, zero immigration, is practically impossible across mainland Australia.
The reality is that deer are now an established part of many Australian landscapes. Pretending otherwise does not constitute policy.
Management, Not Fantasy
None of this means deer impacts should be ignored.
It does mean governments need to be honest about what is achievable.
The Wild Duck Island project actually reinforces the case for:
- targeted management
- protection of high-value environmental assets
- coordinated recreational and professional control
- adaptive management based on measurable impacts
Rather than simplistic slogans about “eradication”.
The researchers themselves note that eradication programs are expensive, difficult and often fail.
That reality matters.
Because on mainland Australia, policy built around unattainable eradication rhetoric risks:
- wasting public money
- spreading resources too thinly
- undermining achievable outcomes
- ignoring the role of recreational hunters
- prioritising ideology over measurable environmental benefit
Good wildlife policy starts with honesty.
And this new science makes one thing abundantly clear:
If deer eradication is extraordinarily difficult on a small isolated island with no reinvasion risk, then promises of eliminating established mainland deer populations are not serious wildlife management policy.
They are fantasy.
