Imported Beavers Gnaw Away At Argentina's Forests

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.