Patagonia's Imported Beavers Flooded Forests

In 1946, Argentina imported 20 beavers from Canada and released them in Tierra del Fuego, Patagonia, hoping to start a fur trade. The trade failed, but the beavers spread with few natural predators, and one recent estimate put their population above 100,000. They felled trees and built dams that flooded forests, roads, and pastures. Researchers have described the damage as "the largest landscape-level alteration in subantarctic forests since the last ice age."

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