Biologist Gerry Kuzyk was hiking with his wife in the remote reaches of the Yukon when he caught the putrid scent of caribou dung wafting through the chill air.Then he saw it -- the biggest pile of animal droppings he had ever seen, 8 feet high and stretching over a half-mile of mountainside.Kuzyk, a researcher with the Yukon Department of Renewable Resources, knew there weren't enough caribou in the entire territory to create such an epic mound. Odder yet, there hadn't been caribou in the area for nearly a century."It was like being in the `Twilight Zone,' " said Rick...