Windhoek (AFP) - A US hunter who paid $350,000 to kill a black rhinoceros in Namibia successfully shot the animal on Monday, saying that his actions would help protect the critically-endangered species. Corey Knowlton, from Texas, downed the rhino with a high-powered rifle after a three-day hunt through the bush with government officials on hand to ensure he killed the correct animal. Knowlton, 36, won the right to shoot the rhino at an auction in Dallas in early 2014 -- attracting fierce criticism from many conservationists and even some death threats. He took a CNN camera crew on the hunt...