Experts in the US fear a rising number of “super pigs” that are proving tough to eradicate could invade northern states.
As a cross-breed combining the Eurasian boar’s survival skills with the size and fertility of domestic swine in Canada, the “super pig” is described as an “ecological train wreck”.
Professor Ryan Brook, one of Canada’s authorities on the issue, added they are the “most invasive animal on the planet”, with the swine capable of spreading disease and devastating crops and wildlife.
“Nobody should be surprised when pigs start walking across that border, if they haven’t already,” Professor Brook said.
“The question is: what will be done about it?”
Northern states like Minnesota, North Dakota and Montana are taking steps to stop the invasion, but it isn’t easy to control the spiralling population.
The pigs are smart and furry, giving them the edge to survive Canadian winters, and they reproduce extremely quickly.
One sow can have six piglets in a litter and raise two litters in a year – which means that even if authorities managed to eliminate 65% of the population each year, they’d still grow.
And hunting could make the problem worse, according to Professor Brook, with the success rate for hunters only about 2- 3%.
The pigs are described as the most invasive animal on the planet. Pic: St. Louis Post-Dispatch via AP
Several states have also banned hunting because it makes the pigs more wary and nocturnal, which makes them tougher to track down.
Instead, methods under consideration are ground traps – like the so-called “BoarBuster” – or net guns fired from helicopters.
Some states have also adopted crowdsourced “Squeal on Pigs” tracking programs, while scientists have studied poisons such as sodium nitrite, but they risk harming other species.
“The only path forward is you have to be really aggressive and you have to use all the tools in the toolbox,” Professor Brook said.
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Pigs already cost $2.5bn (£1.98bn) in damage to crops in the US each year, mostly in southern states.
They have also, on occasion, been known to attack humans, with one woman killed in Texas in 2019.
The animals are not native to North America, but have roamed there for centuries.
The problems in Canada date back to the 1980s, when farmers were encouraged to raise wild boar, before the market collapsed in 2001 and some frustrated farmers simply set the animals free.