Received death threat and scathing criticism. some call conservation hunting a horrific idea. these are majestic creatures and their worth alive is far greater than dead. reporter: the biggest threats are poachers and the rhinos themselves. i m cory. nice to meet you. reporter: knowlton is told by government observers to target four specific rhinos considered a high priority threat to the herd. that s the story of this rhino spotted by cameras as a watering hole just before sunrise. last year it killed another rhino in a gruesome fight. the hunt begins. the african brush is dense. knowlton will have a split second to decide whether to pull the trigger. it would be a catastrophic mistake for cory if he were to shoot the wrong rhino, one that is not on the list of eligible rhinos to be taken out of the