Imported Beavers Gnaw Away At Argentina's Forests

June 8, 2011

Juan Forero

Juan Forero
A beaver dam sits on the appropriately named Beaver Creek. Beavers aren't native to the region, but you would never know it — there are dams, beaver lodges and felled trees all over the creek.
A beaver swims in Tierra del Fuego National Park. The beavers are cutting and flooding forests across the vast, remote Tierra del Fuego archipelago. With no natural predators, they mow down forests unchecked, and their dams create lagoons that suffocate trees and vegetation. Floods over roads and cattle-grazing pastures have caused millions in damages.
A beaver swims in Tierra del Fuego. The beavers are cutting and flooding forests across the vast, remote archipelago. With no natural predators, they mow down forests unchecked, and their dams create lagoons that suffocate trees and vegetation. The beavers also flood over roads and cattle-grazing pastures, causing millions in damages.
Juan Forero
Pablo Kunzle, a park ranger in Tierra del Fuego National Park on Argentina's southernmost fringe, shows off the trunk of a tree whittled down by beavers. "Unfortunately," Kunzle says, "they're almost the perfect machine." Once the tree is toppled, he says, it'll be used to buttress the beaver's dam or lodge.

At the frosty southernmost tip of South America, a devastating problem is afoot — and it's a very furry one. A small group of Canadian beavers introduced into the wild in 1946 have multiplied into an army of 200,000 across a remote archipelago.

And those beavers have been busy, chomping and gnawing their way through pristine forests.

In the middle of Tierra del Fuego National Park in southern Argentina, park ranger Pablo Kunzle stands on a dam packed tight with branches and mud, built by industrious beavers on a fast-moving stream appropriately called Beaver Creek. He breaks through ice to fish out a steel trap he'd laid for the semi-aquatic beavers.

It's the onset of winter here in the southern hemisphere, as snow covers the ground and strong winds blow off craggy peaks.

"I put the trap here," Kunzle says atop the dam. "I think I might have gotten something."

As a park ranger, Kunzle catalogues the felled trees and the flooded forests. Then there's his role as trapper, to control the population of the web-footed mammals in one section of the park.

"Almost!" Kunzle says as he examines an empty trap, explaining that this time, the beaver touched the steel jaws, set them off and got away. The traps are designed to slam down on the animal's head, killing it in seconds.

Fur Trade Gone Wrong

This is not what Argentine administrators had in mind when they imported 50 beavers from Canada, but their goal of spurring a fur trade never took off.

Instead, the beavers did, helped by the fact that there are no natural predators here — no wolves, no bears.

Laura Malmierca, a parks service biologist, says the first beavers were let loose in Lake Fagnano in the middle of Tierra del Fuego.

From there, she says, they spread across a string of islands along the Beagle Channel. Now, a colony has been established on the Brunswick Peninsula in Chile on continental South America, and that has alarmed officials in both countries.

At the Austral Center for Scientific Investigations, Guillermo Deferrari, a biologist, pulls out the beaver's main weapon from a bag: its durable teeth. He says the teeth keep growing throughout a beaver's life — teeth so strong they chip through big trees.

To stem the beaver population, authorities have paid rewards to trappers, but that didn't have much of an effect because few people here know how to trap.

A Delicacy? Not Quite

In the tourist town of Ushuaia, they even tried to get restaurants to serve beaver dishes to generate a trade in beaver meat.

"It's dark-colored, it's a little bit tough, it takes a long time to cook. It's not amazing, but it's fine," says Ezequiel Rodriguez, owner of Gustino, a restaurant that tried serving beaver dishes. Rodriguez says that idea just didn't fly.

The latest proposal is a complete eradication, to kill every single beaver as both Chile and Argentina have agreed. Logistically, though, it'll be hard in rugged, wet terrain.

And then there are the tourists to consider. They come to the region to hike, to take in the penguins, the roaring sea lions, but they also come for the beavers. They are, after all, very cute: round, furry, with buck teeth and long whiskers, and you just can't fault their work ethic.

Trudging through newly fallen snow, Kunzle, the park ranger, says tourists don't know the whole story.

"There are few who are well-informed about the beavers," Kunzle says, "and the damages they cause."

Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.

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