Almost 50 species of mammal are known to live in Canyonlands. Some animals, like desert cottontails, kangaroo rats and mule deer, are common and may be seen by a majority of visitors. However, many desert animals are inactive during daylight hours or wary of humans, so sightings can be truly special events. Tracks and scat are the most common signs of an animal's presence. Canyonlands' hot climate and lack of water seems to favor small mammals. Because of their size, these animals are less able to migrate, but have an easier time finding shelter and require less food and water to live. Rodents are numerous: there are nine species of mice and rats alone. Beavers, the largest North American rodent, are found along the Colorado and Green rivers. Since the rivers are too swift and broad to dam, beavers burrow dens in the banks. One animal uniquely adapted to life in the desert is the kangaroo rat. This rat lives its entire life consuming nothing but plant matter. Its body produces water by metabolizing the food it eats. However, even the kangaroo rat is prone to spending the hottest daylight hours sleeping in a cool underground burrow and may even plug the opening with dirt or debris for insulation.
Larger mammals, like mule deer and mountain lions, must cover more territory in order to find food and water, and sometimes migrate to nearby mountains during summer. In Utah, around 80% of a mountain lion's diet consists of mule deer, so these animals are never far apart. However, unlike mule deer, mountain lion sightings are very rare. Desert bighorn sheep live year-round in Canyonlands. These animals roam the talus slopes and side canyons along the rivers, foraging on plants and negotiating the steep, rocky terrain with the greatest of ease. Once in danger of becoming extinct, the desert bighorn are now making a tentative comeback that has been fueled by the healthy herds in Canyonlands.
An interesting fall visitor to Canyonlands is the black bear. An unusual sight in the red rock canyons, black bears follow river and stream corridors, like Salt Creek Canyon in the Needles District, that flow from nearby mountains. These visits generally occur in late August and September when prickly pear cacti and hackberry trees bear their fruit. The bears return to the mountains before winter.