Ditch pig eradication programs: experts

Marty Silk |

Damage caused by feral pigs costs Australian farmers about $100 million each year.
Damage caused by feral pigs costs Australian farmers about $100 million each year.

Australia should stop trying eradicate the millions of feral pigs roaming the continent and instead batten down the hatches against them, experts say.

No one knows exactly how many of the hairy pests inhabit the country although estimates range from 3.2 million to 30 million.

They cost farmers about $100 million each year by destroying crops and pasture, spreading weeds and diseases, and damaging infrastructure like fences, according to Australian Pork Limited.

They’re also fouling up wilderness areas and eating native animals, particularly in northern Australia.

Kelli Leatham, who runs the Mapoon Land and Sea Rangers, says feral pigs are digging up pristine wetlands on Queensland’s Cape York.

“If you see some of swamps and plains around, you know, it’s not just holes from them, it’s craters … the destruction,” she told AAP.

Dr Justin Perry, who works for the North Australian Indigenous Land and Sea Management Alliance, has studied pigs for decades.

He says sus scrofa, as scientists know them, are one of the most successful feral animals on the planet.

They have adapted to Australia’s varied climate, face few natural predators and devote all their time to seeking enough food to breed.

“If you’re in a place that’s not protein limited, they’ll just keep punching out babies all year round,” Dr Perry says.

“I’ve heard people talking about pigs in places which had heaps of food punching out three litters of piglets per year, which is just an incredible thing.

“So you can just fill an area up with pigs really, really quickly.”

Attempts to exterminate wild pigs are likely to fail, he says. New research shows aerial culls haven’t made a difference.

Dr Perry led a recent pig study involving the CSIRO, James Cook University and Queensland’s Department of Environment and Science.

The team took samples of insects, fish, reptiles, birds and water quality along with temperature readings from 15 Cape York wetlands in both wet and dry seasons.

Dr Jon Marshall, a freshwater ecologist with the Queensland government, says areas frequented by hogs hosted dramatically fewer insect numbers and there was less variety.

“So, they really do trash wetlands quite badly,” he says.

Dr Perry’s team also looked into whether shooting, baiting or fencing were protecting habitats for threatened species such as marine turtles.

Used in isolation, they found the methods make no difference.

That’s no surprise to Ms Leatham, whose team can shoot up to 900 pigs during turtle nesting season.

After a cull, the Mapoon Rangers know it’s only a matter of time before more move in from surrounding areas.

“The numbers aren’t declining from what we’re culling every year, it’s pretty well the same. 

“And it’s hard, you know, they can travel for miles and miles coming in and they can come from cattle properties and stuff where people don’t bother to do anything about it.”

Dr Perry says policymakers should look at evidence, dump pig body counts and focus on protecting things they value from the pests.

For a pristine wetland, that could include a mix of controls such as fencing, traps and culling, he says.

“It’s different management regime that really requires you to say: what are we trying to protect, how much money we’ve got, how many resources have we got and what can we actually do about it.

“So your focus isn’t how many pigs can we kill, it’s how do we protect that value.”

As part of the research involved, Indigenous organisations Kalan Enterprises and Aak Puul Ngantam Cape York helped collect and upload data into virtual maps.

They continue to update them, allowing analysis on whether different types of pig control work.

Dr Perry says including Indigenous rangers, landholders and farmers in pig control studies is crucial as they’re ultimately the ones who manage the problem on behalf of government.

Controlling feral swine more effectively is critical, he says, after a recent Japanese encephalitis outbreak in Australia and foot-and-mouth disease outbreak in Indonesia.

Feral pigs carry both diseases, among many others, which risk the health of humans and animals.

“If we did have to respond to a national biosecurity threat that started spreading through feral pigs, we kind of need to know how to do this,” Dr Perry says.

“We need to know what’s the best strategy to apply for any particular purpose.”

This AAP article was made possible by support from the Meta Australian News Fund and The Walkley Foundation.