News from the Field

From pigs to progress: managing feral swine for wildlife

22 Jun. 2023
Sally Gray/AWC

Feral pigs are a serious environmental pest across Australia. They are found in all states and territories, particularly around wetlands and river systems, and are estimated to number over 23.5 million – almost one pig for every Australian. They are incredibly destructive, and their impact is felt throughout every ecosystem where they are found.

The biology and ecology of the feral pig make them an extremely successful animal in the Australian environment. They are highly adaptable, with populations occurring from semi-arid rangelands to alpine environments and tropical rainforests.

Across our sanctuaries and partnership areas, Australian Wildlife Conservancy (AWC) closely monitors feral pig populations and removes them from the environment as part of our national feral herbivore management program.

A pig wallows in shallow waters at the edge of a wetland, Piccaninny Plains. Sally Gray/AWC
A pig wallows in shallow waters at the edge of a wetland, Piccaninny Plains.

Destructive swine

At Piccaninny Plains Wildlife Sanctuary in Far North Queensland, feral pigs are particularly abundant and extremely damaging to the fragile and diverse ecological environments. Between January 2022 and June 2023, over 1,600 pigs were removed from the sanctuary and the number for the last decade reaches almost 10,000.

“Pigs cause enormous damage to wetlands, particularly on the margins where they root up and eat succulent water plants, mussels and crabs,” explains Piccaninny Plains Sanctuary Manager Sally Gray.

“They disturb mature trees leading to root instability and destroy recruitment seedlings. They disturb water bodies to such an extent that they dry out early in the dry season – affecting the habitat for migratory bird species that historically visit Piccaninny. Pigs also predate on eggs and young of ground-dwelling animals, such as emu eggs and chicks and goanna eggs.”

Feral pigs are also a significant biosecurity risk as they can also host animal diseases that can be transmitted to other species. In dirt on their feet and fur, they can also spread plant pathogens such as Phytophthora cinnamomi, which causes plant dieback.

Damage left by a drove of feral pigs, Piccaninny Plains. Sally Gray/AWC
Damage left by a drove of feral pigs, Piccaninny Plains.

Feral by name, feral by nature

Far from the portly pink pigs you expect to see on farms, feral pigs are smaller, leaner, and heavily muscled. Individuals caught at Piccaninny have topped the scales at over 120kg and are dark, almost black, with thick coarse hairs – although sometimes bald – with large, curved tusks.

Their high breeding capacity can allow numbers to build up quickly. Under good seasonal conditions, breeding occurs year-round and sows can produce two litters per year, with up to 10 piglets in each one. They are omnivorous and switch food preferences depending on available resources.

Feral pigs are also defensive, cranky, and willingly charge people when cornered. “During our first wet season here when feral pig numbers were very high, Graham (Piccaninny Plains sanctuary manager) would mow the Operations Centre ground with a rifle on board!” explains Sally.

“These days, with our successful control program continuing, we rarely see pigs while out and about. Ten years ago, was a very different story, with large mobs of up to 75 pigs roaming from the front gate to the homestead and everywhere in between.”

An adult boar wades through water, kicking up slit and mud, at Piccaninny Plains. Sally Gray/AWC
An adult boar wades through water, kicking up slit and mud, at Piccaninny Plains.

Managing pigs at Piccaninny

Removing pigs from across the 165,000 hectares of Piccaninny Plains is a complicated task. The sanctuary is subject to the ‘wet’ and ‘dry’ seasons typical across northern Australia. In summer, monsoonal rains swell the rivers and creeks into a continuous expanse of water that spreads over hundreds of square kilometres, effectively cutting off access. Once the monsoon withdraws, the land becomes progressively drier and brings with it fires and dried-up river beds.

The pig management program operates all year round. For ten months of the year, this is done by aerial control, with helicopters used to hunt and shoot pigs across the vast and varied landscapes. On-ground patrols are continual, with the assistance of feral tracking dogs, Picca and Yindi.

The number of pigs removed each year through these endeavours averages 950.

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