Invasive speciesExperts say now’s the time to get on top of the destructive impact of the invasive species on vulnerable ecosystems
If there is one thing beef cattle farmer Ted Rowley has learned while trying to manage feral deer on his property, it is this: for every deer that you see, there are at least another 10 that you can’t see.
“In the beginning you see a few deer and think that’s pretty cute,” he says. “But what you don’t see is the very large number that are across the landscape.”
Australians have increasingly become used to the idea that deer will turn up in places that they shouldn’t, including near and in major cities. This week, two men were reportedly startled by a deer while sunbathing on a beach in the Royal national park south of Sydney – an event that prompted them to flee into the bush, get lost, need rescuing and end up fined for breaching coronavirus restrictions.
Last month a deer was seen running through the streets of Fitzroy, a short stroll from the Melbourne CBD, during the city’s recent lockdown. It was later captured and euthanised. Back in October, two deer roamed through streets in the inner Sydney suburbs of Leichhardt, Balmain and Annandale.
While they may have been in the headlines recently, feral deer have not had the same profile as other invasive species – think cats, foxes and pigs – but they have had a similarly destructive impact on vulnerable ecosystems. They also pose a biosecurity threat as potential carriers of disease and are a road safety risk in and around towns and cities.
A federal parliamentary inquiry examining the impacts of feral deer, goats and pigs recently found they pose an urgent and intensifying risk to Australia’s natural environmental values, agricultural productivity, and cultural heritage.
Rowley, who runs cattle across about 800 acres west of Jindabyne, next to the Kosciuszko national park in New South Wales, became aware a large number of deer lived locally soon after he moved to the area about a decade ago.
At its worst, he estimates 300 to 500 fallow deer were wandering onto the property at night and the potential stocking rate on the farm was reduced by half because the animals were eating the improved pasture.
Neighbouring farms were experiencing a similar problem and they formed a group to campaign for tighter pest controls in the state.
Rowley now manages the problem by hiring a deer harvester to shoot feral deer for commercial use. He and neighbours also use thermal scanners and night vision rifle scopes to detect deer.
“The really important thing about deer is they learn very quickly. They learn how to avoid spotlights and noise and will change their behaviour after one or two exposures to a technique,” Rowley says. “So after five years we still have a major pest problem.”
Experts say Australia has a window of opportunity right now to try to bring deer populations – which are spreading further across the country and growing in number – under control.
“For the last 10 years I have been hearing lots of stories of deer having negative impacts on farms, environmentally sensitive areas, replanting areas and roads,” says Andrew Cox, the chief executive of the Invasive Species Council.
“These stories have been increasing in frequency.”
Cox describes deer as “voracious eaters” that can strip the under-storey of large areas bare.
“I sometimes describe it as like a slow-moving rabbit plague. And at the moment we don’t have the tools to stop it”.
The Morrison government is funding work that aims to gain both a better understanding of the size of the problem and develop new methods to tackle it.
Through the Centre for Invasive Species Solutions it has appointed a national deer management coordinator, Annelise Wiebkin, who is an ecologist with a biosecurity background.
She is developing a national management plan, to be completed in the next year, and Rowley is one member of a committee that is providing advice.
Wiebkin says although deer have been present in Australia for a long time, the problem really emerged in the past 20 years after the peak in deer farming in the 1990s.
As a result of deer being released or translocated, seed populations had formed in many places and numbers had grown, she said.
The size of deer populations nationally is unclear, though Wiebkin estimates it is about 2 million, with 1 million found in Victoria alone.
A 2020 survey of populations in NSW found they were present in about 22% of the state, up from 18% in 2016.
In Tasmania, there are concerns the state’s one species of feral deer – fallow – is spreading into the wilderness world heritage area.
“I think it’s safe to say they’re spreading in distribution and increasing in number in all states,” Wiebkin says.
“We have a window of opportunity to get on top of it before it spreads further.”
Part of Wiebkin’s role is to try to develop nationally consistent approaches to deer.
NSW, Queensland, Western Australia, South Australia, the Northern Territory and the ACT all recognise deer as a feral pest.
In Victoria and Tasmania, they are still managed as a game resource, which Wiebkin says places limitations on what landholders can do to manage deer.
Victoria, however, is reviewing its Wildlife Act and has released a new deer strategy that aims to prevent the establishment of new populations.
Tim Beshara, of the Wilderness Society, says states that regulate deer as game species are “actively pursuing a policy of promoting the persistence of deer in our forests forever”.
“They do this whatever the cost to the native species,” he says.
The other concern is that the only tool for controlling populations at present is aerial or on-ground shooting and some trapping.
The costs of this management are high and for obvious safety reasons its use is limited in more populated urban areas.
In some breeding seasons, populations can grow by as much as 35%, meaning a significant number of animals have to be culled just to keep populations at the same level.
There’s currently no bait registered in Australia for deer, but Wiebkin says there will be research into this in the near future.
“I would like to see more tools available for land managers,” she says.
“Aerial culls in parks or on private land will continue and are a very effective way to drop numbers.
“But some populations are so high that literally thousands need to be managed.”
She says Australia needs to be vigilant about protecting its world heritage areas and nationally significant forests from deer.
“It’s also important to get on top of the small isolated patches of deer because they are going to grow one day,” she says.
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