Mountain lion- also known as cougar
Desert bighorn sheep, thriving now that the competing feral burros have been removed, are a common sight, often in small bands moving along ledges. Coyotes, with their distinctive twilight song, are common, especially near water, as are ringtail cats and spotted skunks. Mule deer are common on both rims and throughout the canyon. Neatly clipped willows along streams are signs of beaver. Bats can be seen in the evening twilight as they dart after insects. Raccoons, mountain lions, bobcats, weasels, and gray foxes are rarer.
Woodrat middens are common in the desert scrub. These rodents live in well-protected burrows under boulders and overhangs, and bring twigs, cactus spines, and almost anything else that is loose, creating middens that may be used for many generations. Study of the midden contents often reveals details of past climate and vegetation patterns in the Grand Canyon.
In the rim forests, shrews, mule deer, black bear, elk, porcupines, red squirrels, and tassel-eared squirrels are all common. Black bear are generally shy of people and rarely seen.
Evolution of the Tassel-eared Squirrels
Two distinct species of tassel-eared squirrels have evolved on each rim, separated by the desert gulf they cannot cross. The two species were once a single species but drier, warmer weather after the last glacial period caused the forests to retreat to the highest part of the plateaus, and created the present desert environment in the Grand Canyon. As a result, the Abert squirrel, gray with white underparts, is found today on the South Rim and other ponderosa pine forests in Arizona, while the Kaibab squirrel, with its black belly and white tail, is found only on the Kaibab Plateau. Both squirrels have upright tassels on their ears and large fluffy tails. Tassel-eared squirrels are completely dependent on the ponderosa pine for their survival. They can often be seen running along the ground to the nearest tree or sitting high on a branch scolding at intruders.
