Ninety-six species of mammals are native to the Trans-Pecos region of Texas--that portion of the state which lies west of the Pecos River and contains the main representation of the Chihuahuan Desert in the United States in addition to Texas' only true mountains. The greatly varied terrain, climate, and vegetation of the Trans-Pecos make its mammal life exceptionally varied as well. In the region may be found mammals ranging from tiny shrews to great elks, from bats to aquatic beavers and muskrats, from desert-dwelling kangaroo rats to forest-loving chipmunks, and from timid mice and rats to predatory cougars and coyotes.