Finally completed it. I had to find and follow mad elephant tracks using hunter sense, which gives you info about things (which you walk slow in), then I had to go to the other side of a river and wait for a while until it made it to the river. Then my shot missed, so I had to chase after it. It was worth it though. Got 10 upgrading points, which Iu sed on my high-cal rifle to give it more ammo capacity, less recoil, and faster reloading.