[P 015 / Larger mammals] are not as confined to certain habitats as others. Thus, [L3 404 / I005 / mule deer], bighorn sheep, bobcats, and other species can be spotted anywhere from the rim to the river.
More restricted in their movements are the smaller mammals: species of mice, rats, skunks, and so on. Beaver can be heard splashing about in some of the still pools in the side canyons. Also found in the Grand Canyon is the cancomistle, sometimes known as the ring-tailed cat. Although it looks catlike, it is actually related to the raccoon family. Sandy gray in color, it is about 30 inches long, half of which is a bushy tail with black and white rings. The cancomistle, curious and friendly, sometimes visits campers as they sit around their fires.
Birds found in the canyon include herons, egrets, ducks, geese, kingfishers, killdeer, sandpipers, avocets, doves, redwings, and pinyon jays.
Perhaps the most famous animal associated with the Grand Canyon, and certainly the most interesting to biologists, is the [I 007 / tassel-eared squirrel]. At one time, thousands of years ago, there was only one species of this creature, and it occupied a wide range in the Southwest. Among the largest and most beautiful squirrels known, with dark gray bodies and with a maroon stripe down the back. They emit a bark that sounds like "chuck-chuck."
Over the centuries, though, the squirrels on the north side of the canyon [L3 405 / evolved into a completely different subspecies] than its cousins to the south. Today the Kaibab squirrel (also known as the [I 007 / Tassel-Eared squirrel]) - with a black belly and a nearly pure-white tail - can be found only within a 350 square-mile range in the Kaibab National Forest to the north. The Abert squirrel, with its white belly and grayish tail, is more widespread throughout the Southwest. Despite their physical differences, they are similar in size and lifestyle.
Many animals living on the canyon floor, especially the smaller mammals, are nocturnal. They sleep in whatever shady crevices they can find during the day, emerging at night to hunt. Campers may wake to find that while they slept, their campsites were visited by spotted skunks (the smallest species in the U.S., about the size of a squirrel), pocket mice, chipmunks, and kangaroo mice.
Spiny lizards and rattlesnakes, including the pink rattlesnake, scamper across scorching sands. Since reptiles are cold-blooded, they depend on the warmth of the sun to recharge their batteries. Better able to withstand the blistering desert heat, they crawl out during the day to soak up the energy they need to hunt for food.
Scorpions - not an insect, but an arachnid related to spiders - are nocturnal. Fearsome in appearance, with their claws and long stinging tails, most scorpions are not lethal to human beings. However, the two most deadly species are found in the bottom of the Grand Canyon. In Arizona, more deaths have occurred from scorpion stings than from the bites and stings of all other creatures combined. Scorpions don't drink water; they get all the moisture they need from their victims' bodies. One night's meal may be enough to feed the scorpion for an entire year.
A few burros still roam the side canyons. These are the descendants of animals brought in by miners and left behind when the mines went bust. Burros are not native to the region; in fact, they were originally imported from North Africa. Because they did not arise in this habitat, they compete with the native bighorn sheep for food and water. The burro population grew so large that in the 1970s the government launched a plan to eradicate them by shooting them. Animal rights activists organized to airlift dozens the animals out of the canyon and turn them over to farms and petting zoos.
