Though the natural quiet of Arches often creates the impression of lifelessness, many animals live here. Birds, lizards and some rodents are seen most frequently, though seasons and weather play a large role in determining what animals are active.
Desert animals have a variety of adaptations for dealing with the temperature and moisture stresses present in Arches. Most desert animals are nocturnal, being most active at night. This can be an adaptation to both predation and hot summer daytime temperatures. Mostly nocturnal animals include kangaroo rats, woodrats (also called packrats), and most other small desert rodents, skunks, ringtails, foxes, bobcats, mountain lions, bats and owls.
Animals that are most active at dawn and dusk are called "crepuscular." These times of day are cooler than mid-day. The half-dark makes prey animals less visible, yet visibility is good enough to locate food. Some animals are crepuscular mostly because their prey is crepuscular. Crepuscular animals include mule deer, coyotes, porcupines, desert cottontails, black-tailed jackrabbits, and many songbirds.
A few desert animals are primarily active during the day, or "diurnal." These include rock squirrels, antelope squirrels, chipmunks, lizards, snakes, hawks, and eagles. Many animals have a temperature range in which they are active, so alter their active times of day depending on the season. Snakes and lizards go into an inactive state of torpor during the winter, are active during the day during the late spring and early fall, and become crepuscular during the heat of summer. Many insects alter their times of activity. Mosquitoes, for example, may be out at night, at dawn, dusk or all day but not at night, depending on the temperatures.
Most animals in this desert climate are nocturnal; that is, they eat, drink and move about at night. Fifty-two kinds of mammals have been sighted in the park. Mule deer (shown in photo at right), bighorn sheep, cottontail rabbits, kit fox and ground squirrels are seen frequently. Birds are common certain times of the year and in certain locations. At least 186 kinds of birds have been seen in the Park. Common ones include pinyon jays, mountain bluebirds, red-tailed hawks and ravens. Visitors who leave their cars during the warm part of the year are almost guaranteed to see lizards! Shy midget-faded rattlesnakes are also present, but are seldom seen. Believe it or not, the hot temperatures (up to 114 degrees Fahrenheit) in the summer are just one of the many harsh conditions for the animals that live here. Animal adaptations are also aimed at coping with the dryness, lack of food, and extreme temperature changes. Every animal needs water to live. In the desert, water isn't always there when you need it. Humans have a great advantage because we can plan ahead, fill up our water bottles, and carry as much water as needed (in the summer, about four quarts per person per day). Animals have to find water nearby on a regular basis, unless they can fly or walk a long way. Some animals have adaptations that help them live in a dry, hot and cold desert. For instance, black-tailed jackrabbit, kit fox, and mule deer all have large ears with lots of blood vessels in them. They stay cooler by radiating heat from their blood to the air. Some animals such as the kangaroo rat have specialized kidneys that can make water out of dry foods, and have specialized nasal passages that prevent too much moisture from escaping when they breathe.
At Arches National Park, water sources for animals include potholes, springs, seeps, washes, and the Colorado River. Potholes are depressions in rock that collect rainwater and generally evaporate in a week or two. Seeps and springs are more reliable water sources. Most washes have flowing water only after rains. Afterwards, some water flows into the Colorado River and some seeps into the sandy wash bottoms, and the washes dry up. The Colorado River is the southern boundary of the park and is too far away to be useful to many animals that live in the park. Since water is precious to all life and is rare in the desert, it is important not to swim in water sources. Sunscreen or bacteria on humans can contaminate the water and kill organisms living in it. Carry enough water so that the lives which depend on these clean water sources are not disturbed.
Desert bighorn sheep are some of the most intriguing mammals of canyon country. They are wary of human contact, and blend so well into the terrain they inhabit, that sightings are a special event. Once feared of becoming extinct, the desert bighorn are making a tentative comeback in southeast Utah due to a comprehensive reintroduction effort by the National Park Service. Desert or Nelson's bighorn sheep (ovis canadensis nelsoni) are considered by most biologists to be a unique subspecies. Desert bighorns have adapted to hot, dry climates, unlike their Rocky Mountain cousins, and have longer legs, lighter coats and smaller bodies. Bighorn sheep are common in ancestral Puebloan and Fremont pictographs, an indication of their presence and prominence in indigenous cultures. Explorers in the late 1600s estimated that more than two million desert bighorn once roamed the southwest. By the late 1800s however, bighorn sheep had disappeared or declined in many areas.
Extremely vulnerable to diseases from livestock, herd after herd of wild sheep were decimated by pathogens like scabies (an ear mite) and anthrax (a bacterial disease) introduced by domestic sheep. Bighorns were also killed by early explorers, settlers and trophy hunters. Increased competition with domesticated cattle and sheep for food didn't help the situation. In 1975, Utah's population numbered around 1,000 sheep. In the early 1980s, biologists began relocating bighorns from a native population in Canyonlands National Park in order to establish new herds. Since sheep are poor dispersers, this is the only way to return them to their historic ranges. To accomplish this, sheep are captured in nets fired from helicopters, their health and age assessed, and suitable animals are transported by ground to a relocation area. Since the program began, sheep have been reestablished in Arches National Park, Capitol Reef National Park and Glen Canyon National Recreation Area. Sheep relocated to the San Rafael Swell west of Arches have created two herds totaling more than 600 animals. Today, the bighorn population in Utah is estimated at 3,000 animals.
There are roughly 75 sheep in Arches, and animals are often sighted along Highway 191 south of the visitor center. Human activity and development continue to threaten the desert bighorn sheep. The mortality rate of first-year lambs at Arches has been alarming in recent years. Though no specific cause has been identified, this trend may be due to increased vehicle traffic along highways coming into Moab. For the remaining herds to survive, intensive management and conservation measures may be necessary. The protection of undeveloped land and wilderness areas is critical to the species' survival, and Arches will continue to play a large role in this effort.
Birds are the most visible animals in Arches. Even on the hottest summer day, turkey vultures and white-throated swifts circle above the rock formations. During winter, juncos and white-crowned sparrows forage around trees and shrubs. While Arches may not be considered a bird watching hot spot, 273 species have been seen in the park, including seasonal and year-round residents as well as migrants. Arches owes much of this diversity to riparian corridors like Courthouse Wash and the Colorado River (which forms the park's southern boundary). In the desert, animal life tends to concentrate around riparian areas because of the abundance of food, water and shelter. During spring and summer, mornings in these areas are filled with birdsong, including blue grosbeaks, yellow-breasted chats, spotted towhees and canyon wrens.
Great blue herons may be seen hunting the shallows for fish, while cooper's hawks deftly maneuver through the tangle of trees beyond the riverbanks. Many birds favor the "upland" areas where grasses, shrubs and small trees dominate. Say's phoebes, black-throated sparrows and western meadowlarks frequent grasslands. Pinyon jays, scrub jays, juniper titmice and black-throated gray warblers are usually seen in pinyon-juniper woodlands. Since they are able to fly, it is difficult to generalize about what birds will be found in a particular habitat. However, regardless of habitat or season, the common raven figures prominently in the desert landscape.
Ravens are intelligent birds that, according to scientists, display abilities to play and problem-solve rare among animals. This jet-black member of the crow family is also very vocal, using a variety of sounds for communication. Perhaps because of these qualities, ravens have achieved a certain stature in both European and Native American folklore. Arches monitors bird populations at several selected locations in both upland and riparian areas.
Almost 50 species of mammal are known to live in Arches. Some, 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 are wary of humans, so sightings can be truly special events. Tracks and scat are the most common signs of an animal's presence.
Arches' hot climate and lack of water favors 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 eleven species of mice and rats alone.
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 Arches, and are frequently sighted along Highway 191 south of the visitor center. These animals roam the talus slopes and side canyons near the Colorado River, 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 nearby Canyonlands National Park.
Amphibians may be the last thing people think of when they visit Arches. However, the park is home to a variety of frogs and toads, as well as one species of salamander. Witnessing a chorus of toads may be one of the most memorable experiences canyon country has to offer. It is an awesome event that can fill a canyon with sound, sometimes for hours. Amphibians are animals that have two life stages: a larval, aquatic form and an adult, terrestrial form. This is the difference between a tadpole and a frog. In Arches, amphibians lay their eggs in the potholes, springs and intermittent streams like Courthouse Wash. Adult amphibians may wander away from water, but usually remain nearby and wait out dry periods in burrows. Breeding (and toad choruses) usually occurs on spring and summer nights after significant rainfall. Male frogs and toads do the vocalizing. Females lay long strings of gelatin-covered eggs which, depending on the species, may hatch within hours. Metamorphosis can take weeks, though the Great Basin spadefoot toad transforms to adulthood in as little as 14 days, the quickest of any amphibian.
Along with cacti and sand dunes, reptiles have become icons of the desert. The only reptiles found in Arches are snakes and lizards, underappreciated, sometimes feared, animals that play an important role in the high desert ecosystem. Lizards and snakes help control insect and rodent populations. In turn, both are potential meals for birds and mammals. All reptiles are cold-blooded or, more accurately, "ectothermic," regulating body temperature via external sources rather than internal metabolism. A reptile's metabolic rate is very low, but so are its energy needs. Since keeping warm in the desert does not require much work, reptiles are well adapted to this environment.
What energy they do generate can be used for reproduction and finding food instead of heating and cooling. Of course, there are drawbacks to this lifestyle. Since they don't pant or sweat, reptiles can't endure extremely high temperatures without shade. Nor can they endure prolonged sub-zero temperatures. When it's cold, reptiles hibernate or enter into an inactive torpor. Food stored as fat in their tails helps lizards survive these long periods of inactivity, so losing a tail can be life threatening. If you visit Arches during the summer, you are sure to see lots of lizards. After birds, these reptiles are the most active animals once daytime temperatures reach 90 degrees and higher.
They are usually visible sunbathing on rocks or chasing insects with their lightning-quick reflexes. Lizards found here include the northern whiptail, the desert spiny, and the colorful western collared lizard. Most of the snakes found in Arches are harmless and nocturnal. All will escape from human confrontations given the opportunity. The midget-faded rattlesnake, a small subspecies of the western rattlesnake, has extremely toxic venom. However, full venom injections occur in only one third of all bites. The midget-faded rattlesnake lives in burrows and rock crevices and is mostly active at night.