TIERRA DEL FUEGO, Argentina (Reuters) - The Great Beaver Plague, as some furious locals call it, began in 1946 with the same good but misguided intentions that have presaged countless other ecological disasters. That year, Argentina's former military government imported 25 pairs of beavers from Canada, hoping they would multiply and create a fur industry among the chilly, lush forests on this large island at the very tip of South America. Multiply they did. But the fur trade never quite caught on, and there were no natural predators. So today there are tens of thousands of beavers wreaking havoc across...