A fur trade scheme goes wrong
In 1946, the government of Argentina imported 20 North American beavers (Castor canadensis) from Canada and released them near Lake Fagnano in Tierra del Fuego. The goal was to establish a commercial fur industry in the remote region. This plan failed, as the market for beaver pelts was already in decline. But for the beavers, Tierra del Fuego was a paradise. The archipelago offered abundant food and water, with one feature missing: natural predators. In North America, beaver populations are controlled by wolves and bears, but in their new South American home, the beavers had no such threats.
Their numbers exploded. From the initial 20 animals, the population grew to an estimated 70,000 to 110,000 individuals today. They spread from the initial release site across the main island and, by the 1990s, had crossed the Strait of Magellan to the South American mainland. The beavers now cover an area of at least 7 million hectares, impacting thousands of kilometers of waterways. The ecological alteration caused by these beavers is considered the largest large-scale change in the subantarctic forests since the last ice age.