Canadian beavers are wreaking havoc in an unexpected location: a swath of forest in South America.

Some 200,000 dam-building creatures are creating harmful floods that threaten Patagonian forests and nearby lakes that cover parts of Chile and Argentina.

In 1946, 25 pairs of beavers were brought to the Chilean and Argentinian archipelago of Tierra del Fuego, in an attempt to bring the fur industry to the area.

But since beavers have no natural predators— like wolves, lynx, or coyotes— in the area, the population swelled over the last 70 years. Their dams have caused damage to thousands of old-growth trees and peat bogs.

A 2015 documentary about the beavers’ introduction to the area referred to the wood-chomping critters as “invaders of the end of the world.”

The damaged area is about double the size of the city of Buenos Aires, according to BBC News.

In November, the Chilean and Argentinian governments began a 10-year mission to exterminate 100,000 beavers with traps, training hunters to eventually eradicate the species.

And this month, the Chilean government will begin a $7.8-million population control project, which also involves placing traps, according to the Los Angeles Times.

Authorities have offered rewards for trapping and killing beavers in the past, but few people in the area actually know how to do that, according to NPR.

A nearby tourist town also tried serving beaver meat as a delicacy, but that didn’t work out too well either.

Animal rights activists have criticized plans to cull the animals, suggesting they should be sent back to Canada.

But Chilean biologists consider that move to be both expensive and impractical, according to the L.A. Times.

Chilean biologist Giorgia Graells told the Times that Patagonian ecosystems are not prepared for the kinds of changes that beavers bring.

“When an area is flooded, the seeds get covered by mud and water and die, and the forest won’t recover,” she said.