Bighorn Sheep rams after sunset, in Shoshone National Forest, Wyoming. During the rut, these rams will compete for access to the ewes to breed. Rams will face each other, rear up on their hind legs, and plunge forward and headbutt. The crack of this sound will echo through the canyons. They've evolved the ability to survive hits like this with not only those massive horns, but thick skulls and strong necks.