The problems with feral pigs in the United States have been well-documented and now the invasive species is learning how to survive harsh winters. 

In Canada, the wild pigs are building "pigloos" to stay warm during the winter. The animals are digging deep into the snow to create tunnels as they use the snow on top as insulation.  

These "pigloos" also allow the animals to hide very well in the winter, which can make it harder for researchers to track their numbers from the air. 

The burrows also mean that the pigs can produce year-round and have up to six babies per litter every year, rapidly increasing the population.

"The growing wild pig population is not an ecological disaster waiting to happen," Ryan Brook, the University of Saskatchewan's lead researcher for the Canadian Wild Pig Project told USask News, "it is already happening."

Parts of the United States have already had problems with feral hogs from Canada coming into the United States. In September, the Canadian hogs were approaching the Montana border, leaving the state worried about the damage they would do to crops and the local ecosystem.