Officials in Argentina's southernmost province of Tierra del Fuego have a battle on their hands with 100,000 invaders - North American Beavers, whose population exploded way beyond expectations.

The Argentine government bought 50 Beavers from Canada in hopes of creating a fur industry.  That failed, but the 50 animals released into the wild in 1946 bred like rodents, without any natural predators like the ones they faced on the other side of the globe.

In just five decades, the busy beavers have caused profound changes in the landscape.  "The change in the forested portion of this biome is the largest landscape-level alteration in the Holocene - that is, approximately 10,000 years," said Ecology Professor Dr. Christopher B. Anderson, who has spent many years in Tierra Del Fuego studying invasive species.  Beavers gnaw through trees to build their dams.  North American trees evolved over the centuries to survive beaver damage and grow back.  The trees on the islands of Tierra Del Fuego tend to die off after the rodents put those giant incisors to work.  The dams themselves interfere with native fish species.

Adrian Schiavini leads Argentina's National Strategy for Invasive Exotic Species; he says rangers would first employ "humane traps" to cull the animals "quickly and effectively".  But experts in beaver hunting will also be brought in from North America:  "The idea is to train a group of hunters and then choose the best from this group and put them to work in seven pilot areas on Isla Grande in Tierra del Fuego," said Mr. Schiavini.