The desert is home to more than 130 species of mammals, such as the Mule deer and pronghorn. The kit fox roams the vast grasslands of the northern desert. The Chihuahuan Desert boasts 3,000 plant species, including more than 500 of the world's 1,500 species of cactus. The desert also harbors North America's largest prairie dog colony as well as nesting sites and migratory habitats for more than 500 bird species. More than 110 native freshwater fish species ply its rivers. In the desert scrub, roadrunners scurry after earless lizards while golden eagles search among the agave and creosote for blacktailed jackrabbits.
The Rio Grande-Rio Bravo mainstem and Rio Conchos contain important large river habitats in an otherwise dry region. Large scale ecological phenomena such as bird migrations also follow these watercourses. The aquatic fauna has evolved to live under highly variable cycles of flooding and drought both within and across years.