Mule deer are one of the most common animals seen in the park. They can often be seen browsing on trees and shrubs, always staying on the move, making themselves less vulnerable to predator attacks. The reclusive and seldom seen mountain lion is active primarily at night. Mountain lions can be found in any of the ecosystems in the park, although they prefer areas in which deer are abundant. An adult lion can kill and eat one or two deer per week. Nocturnal mammals such as skunks and raccoons are often found in riparian areas. The hog-nosed skunk is a rooter that uses its long claws and pig-like snout to dig in the ground for beetles, grubs, and worms. Raccoons search for food after dark near running streams. Their diet consists of fish and frogs, as well as mesquite beans, cactus fruits, and berries.