Female pigs may be the "factories" of feral populations, but a new study suggests male pigs are the disease "super spreaders".

The research, published in the peer-reviewed journal eLife in February, analysed the movement of 146 feral pigs at nine locations in Queensland and New South Wales to create models of how disease spreads through feral populations. 

Tatiana Proboste, a research fellow at the University of Queensland's (UQ) School of Veterinary Science, looked at more than a decade's worth of data from GPS collars attached to pigs provided by the NSW and Queensland governments.

"Males are actually the super spreaders," Dr Proboste said.

"They're acting as a very crucial connector between different groups.

"When we think about disease transmission, this might be a very key role."

Dr Proboste said while female pigs had strong social bonds within their own mob, males had a higher chance of spreading disease.

"Males interact more with different groups of pigs, whereas females travel less and mostly stay within their own herd," she said.

"Our data also showed feral pigs have more contact with each other in summer, which means a disease is expected to spread further and faster between December and February."

The invasive animals are considered a destructive environmental pest and are known carriers of several dangerous pathogens and parasites, including foot and mouth disease, Japanese encephalitis virus (JEV), and African swine fever.

Matt Gentle from Queensland's Department of Primary Industries, which collaborated with UQ on the project, said the data would help to predict how biosecurity threats might spread through pig populations.

"It's really important to better inform disease preparedness models," Mr Gentle said.

"Those models are used to help predict what happens if there is an outbreak of disease in pigs.

"We can look at the rate of spread and we can look at management techniques in order to reduce the spread."

Population problem

The actual size of the feral pig population in Australia is not known, but female pigs can breed from four months old and can have up to three litters of as many as 12 piglets in a year.

The National Feral Pig Action Plan, a government-funded industry-led management program, estimated the population was upwards of 3.5 million, but previous federal governmentshave estimated it could be as high as 25 million.

The plan, which aims to manage and reduce the impacts of feral pigs, estimates feral pigs inhabit about 45 per cent of the country.

Population management usually happens through aerial shooting or baiting programs, which National Feral Pig Management coordinator Heather Channon said ideally targeted the breeding cycle.

"The sows are the factories of feral pig populations. If we don't control them effectively, the problem will grow," Dr Channon said.

"We need to be focusing on both the boars [males] and sows [females].

"Boars have a larger home range than sows and will be visiting different groups for mating."

Dr Channon said the animals cost the Australian economy $156 million a year in damage and control.

"Feral pigs have an enormous impact on Australia's environment and our agricultural industries," she said.

"They're so resilient, so adaptive, and they're very intelligent.

"It means their management becomes very challenging."

Gender complexity

Farmers have been increasingly concerned about the population size and subsequent biosecurity threat feral pigs pose.

While the findings will inform emergency response strategies for disease outbreaks, Dr Proboste said reducing the population was a complex issue.

"In theory, yes, we will probably be looking into controlling males in terms of disease transmissions," she said.

"But I think in practice it's really hard to actually focus on only the males as the control measures normally target both sexes."

Jamie Petrie, president of the Capricornia Pest Management Group, specialises in control programs in central Queensland.

One of many not-for-profit groups helping landholders tackle the issue around the state, he said the population had become too large for gender specific methods to be effective.

"We're not just dealing with a handful of females and males," he said.

"The pig population is out of control."

https://www.abc.net.au/news/rural/2025-03-13/male-feral-pigs-identified-as-disease-super-spreaders/105031844

 

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