Key Takeaways:
- Feral pigs are causing significant damage to the environment and culturally significant sites in Australia, particularly in the Bunya Mountains and Cape York Peninsula.
- The pigs are spreading a deadly disease called dieback, which is killing off bunya pines, and are also destroying habitats of other native species such as platypuses.
- The invasive species are estimated to number between 2.4 and 4 million nationally, with conservationists and Indigenous traditional custodians sounding the alarm to avoid further damage.
- Control methods such as shooting, trapping, and targeted poisoning are being used, but effective control needs to be professional, humane, and done at a landscape scale.
- Urgent investment is needed to equip Indigenous owners with the resources to tackle the invasive pig issue, particularly in the northernmost part of the country.
Introduction to the Problem
High up in an ancient conifer rainforest, at what was once the largest Indigenous gathering place in eastern Australia, there is sunlight where there shouldn’t be. Among the eponymous pine trees of the Bunya Mountains, in south-east Queensland, a deadly disease has taken root. Walking through the forest, Adrian Bauwens, a Wakka Wakka man, says pockets of sunlight have replaced what is “usually quite a dense canopy where’s it’s quite heavily shaded”. The towering bunya pines are afflicted by a plant pathogen known as dieback and becoming skeletal, dropping their leaves and limbs.
The Culprit: Feral Pigs
The culprit is Phytophthora, a type of water mould that spreads through soil and attaches itself to the roots of trees, cutting off nutrient and water supply. However, the spread of dieback is being worsened by a porcine threat. Feral pigs are “running quite wild”, Bauwens says; “trotting around in dieback areas … spreading it through the mountain by digging it up”. The destructive invasive species use walking tracks and bike trials in the national park as “highways”, attracted by the promise of food in the bunya’s large nut-filled pine cones.
Cultural Significance of the Bunya Pines
A forest health officer at the Bunya Peoples’ Aboriginal Corporation, Bauwen is concerned for the fate of trees, which have been described as “living fossils” and are thought to date back 145m years to the Jurassic period. “[It] is a culturally significant tree to us,” he says. Thousands of Indigenous Australians of different tribes once travelled long distances to converge on the Bunya Mountains, to visit and celebrate the pines. “It acted as a bit of a parliament house, where tribal disputes, marriages and ceremonies took place,” Bauwen says.
The Feral Pig Problem
Feral pigs, Sus scrofa, originate from the arrival of the First Fleet and have since spread across 45% of Australia, with higher concentration in the country’s north-east. According to a 2020 estimate, the pests numbered between 2.4 and 4 million nationally, though experts say the true number is likely far higher now. Three years of favourable weather have resulted in booming pig populations, which has conservationists and Indigenous traditional custodians sounding the alarm to avoid further damage to ecologically and culturally significant sites.
Severe Ecological Imbalances
Because of heavy rainfall that has yielded high nutrient loads, the scale of the feral pig problem is “much higher than what has been experienced at any point before”, says Reece Pianta, advocacy director at the Invasive Species Council. “Australian landscapes didn’t evolve for hard-hoofed animals and aggressive foragers with the mass of a feral pig … we are seeing severe ecological imbalances starting to occur.” Pianta says the council is increasingly receiving reports of pigs foraging at sea turtle nesting grounds – in places such as western Cape York and Bribie Island – and eating eggs and hatchlings.
Impact on Native Species
In the Northern Territory, feral pigs have become a staple part of the diet of the saltwater crocodile, helping to drive a rebound in the reptile’s population over the last 50 years. The Top End croc population consumes about six feral pigs per sq km of wetland floodplain annually, research estimates. However, Euan Ritchie, a professor of wildlife ecology and conservation at Deakin University, says it is unclear whether crocodiles can have a meaningful effect on keeping pig numbers down. “The problem with pigs is … they’re really widespread, they’re quite adaptable animals and they can breed really rapidly,” he says.
Devastating Impacts
Alfred Hunter, a Djabugay Bulmba ranger in far north Queensland, has noted feral pig damage to platypus habitat. In a project with WWF Australia earlier this year, rangers identified platypuses in waterways near the town of Kuranda for the first time in decades, after fears the monotremes had become locally extinct. But they were concerned about the presence of feral pigs, which “dig along the sides of the riverbanks and creekbanks” and had been spotted on trail cameras, Hunter says. “Platypuses normally nest underneath the bank.” Trevor Meldrum, a Kuuku Yalangi man and an environmental operations manager at Cape York Weeds and Feral Animals, has seen similar damage in his region, with rock art painting sites being rubbed right through and wetlands being destroyed.
Control Methods
Control methods such as shooting, trapping, and targeted poisoning are being used to control the feral pig population. While private hunting can also remove pigs from the population – donations of carcasses to crocodile farms have occurred in the past – in the US, bounty programs have not helped eradicate the animals. “Effective feral pig control needs to be professional and humane and done at a landscape scale,” Pianta says. “We know that to achieve pig population reduction, you need to remove greater than 70% of their number each year.” The Queensland government has invested $2m in addressing the state’s feral pig problem, but Meldrum would like to see urgent investment in the northernmost part of the country, to equip Indigenous owners on the Cape York peninsula with the resources to tackle the invasive pig issue before it worsens.
