At Grand Canyon 75 species of mammals, 50 species of reptiles and amphibians, 25 species of fish, and over 300 species of birds exist.
The South Rim of Grand Canyon lies on the edge of a high plateau whose gray-green forests stand out in sharp contrast to the arid lands below the rim. From here the cliffs drop 5000 feet/1524 m to the Colorado River, crossing several biotic zones in the process. It is a landscape characterized by abundant sunshine, extremes of temperature, and long periods of drought punctuated by torrential downpours in summer and snow in winter. The soil is thin; bedrock lies just a few inches below the surface. The competition for moisture in this dry land is keen.
On the rim at elevations above 7000 feet/2134 m, ponderosa pine is the dominant tree in the forest. Below 7000 feet/2134 m, pinyon pine and Utah juniper are the dominant trees. Gambel oak is another common member of the forest. The trees are interspersed with drought-resistant shrubs like cliffrose, fernbush, and serviceberry. Warm, sunny areas along the rim may be home to desert plants like banana yucca and claretcup cactus.
Below the rim, it’s another world. The temperature within the inner canyon can be as much as 30 degrees F/18 degrees Chigher than temperatures on the rim. Summertime highs along the Colorado River can reach 120 degrees F/49 degrees C. Much of the inner canyon is considered desert, excluding the areas along the river and tributary streams which have rich riparian (streamside) habitat. Much of the vegetation in the inner canyon is typical of that found in deserts to the south: cacti and drought-resistant shrubs. Riparian plants include thickets of willow and tamarisk.
The park is home to a wide variety of animals. Mule deer are common throughout the park and are the mammals most commonly seen on the rim. Desert bighorn inhabit the remote slopes of the inner canyon but are occasionally seen on established trails. Bobcats and coyotes range from rim to river, and a small population of mountain lions exists in the park. Among the smaller mammals that inhabit Grand Canyon are ringtails (closely related to raccoons), beavers, gophers, chipmunks, several varieties of squirrels, rabbits and bats. Reptiles and amphibians are represented by a wide variety of lizards, snakes (including the unique Grand Canyon “pink” rattlesnake), turtles, frogs, toads and salamanders. Hundreds of species of birds make their home in the park, along with countless insects and arachnids (spiders and scorpions).
Grand Canyon National Park is home to a number of threatened and endangered species. The native Colorado River fish have suffered as a result of the dramatic changes in water volume, temperature and sediment load since the completion of Glen Canyon Dam in 1963. These fish include the Colorado squawfish, humpback chub, and bonytail chub. Several species of endangered birds make Grand Canyon home, including the peregrine falcon, bald eagle, and willow flycatcher. A number of endangered plants can also be found in the park, including. More and more, protected lands like Grand Canyon National Park provide a refuge for plants and animals that are under increasing pressure elsewhere.