The Grand Canyon is a steep-sided canyon carved by the Colorado River in the U.S. state of Arizona. The canyon and adjacent rim are contained within Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Prashant National Monument, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation.
The Grand Canyon is 446 km long and up to 29 km wide and attains a depth of over 1,857 meters. Nearly two billion years of Earth’s geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 to 6 million years ago. Since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs, simultaneously deepening and widening the canyon.
For thousands of years, the area has been continuously inhabited by Native Americans, who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon a holy site, and made pilgrimages to it.
The Park contains several major ecosystems. The five life zones are the Lower Sonoran, Upper Sonoran, Transition, Canadian, and Hudsonian stems.
Raccoons, weasels, bobcats, gray foxes, and mountain lions live in this region, but the latter are much rarer. Mule deer and desert bighorn sheep are the ungulates that frequent the river corridor. Mule deer are generally not permanent residents along the river, but travel down from the rim when food and water resources there become scarce
Some rodents, such as beavers, antelope squirrels and pocket mice are also found here. Grand Canyon bats typically roost in desert uplands, but forage on the abundance of insects along the river and its tributaries. In addition to bats, coyotes, ringtails, and spotted skunks are the most numerous riparian predators and prey on invertebrates, rodents, and reptiles.
Upper Sonoran and Transition
This zone is generally dominated by black brush, sagebrush, and pinyon-juniper woodlands. Approximately 30 bird species breed primarily in the desert uplands and cliffs of the inner canyon. Virtually all bird species present breed in other suitable habitats throughout the Sonoran and Mohave deserts. The abundance of bats, swifts, and riparian birds provides ample food for peregrines, and suitable eyrie sites are plentiful along the steep canyon walls.