Many visitors would be surprised to find out that 75 species of mammals inhabit the deserts and mountains of Big Bend National Park. Living in an area with high temperatures and low rainfall forces many animals to live extremely cautious lifestyles. Many leave their burrows only under cover of night. Others may forage during the cool of early the early morning. Larger mammals include whitetail and mule deer, coyote, mountain lion, and black bear. The snuffling you hear around your campsite at night may be a gray fox or a band of hungry javelina. Bats make up the largest portion of the park's mammal species. 20 different species have been observed here, including the endangered Mexican Long-nosed Bat, which has been found nowhere else in the entire United States.