More subtle than Grand Canyon’s geology, but equally fascinating, is the park’s ecology. First-time visitors often assume the Canyon is barren and lifeless. In fact, this is anything but the case. Over 6,000 feet of sudden elevation change creates a stunning range of life zones lying remarkably close to one another. Nowhere is this more apparent than the North Kaibab Trail, which starts in the cool boreal forest of the North Rim and ends up in the scorching desert at the bottom of the Canyon. In a matter of hours, hikers pass by spruce trees and cacti, the equivalent of traveling from Canada to Mexico in a single day.
All told, Grand Canyon is home to 17 fish, 47 reptiles, 89 mammals, and 355 bird species. There are also over 1,750 plant species in Grand Canyon—more than in any other national park. The wide range of biodiversity in Grand Canyon is due, more than anything else, to temperature and precipitation, both of which are affected by elevation. Generally speaking, temperatures rise and aridity increases as you descend into the Canyon. From the rim to the river, the contrast between environments is often extreme. At the sweltering bottom of western Grand Canyon, an average of six inches of rain falls a year, and only rugged desert plants such as cacti and yucca can survive. The cool, high plateaus of the North Rim, however, generally receive over 30 inches of precipitation a year, supporting dense forests of spruce, fir, and aspen.
The Canyon’s wide range of climates also affects the distribution of animals. Cold-blooded reptiles that thrive in the warm Inner Canyon are much less common on the rim, and rim dwellers that require a steady source of water are poorly adapted to much of the Inner Canyon. Animals are also affected by the distribution of plants. Because plants form the foundation of a healthy food chain, they play a vital role in determining which animals can live where.
But plants are also dependent on animals. Consider the relationship between the pinyon pine and the pinyon jay, a pale blue bird found throughout the Colorado Plateau. Pinyon pines produce large seeds too heavy to be dispersed by the wind. But the seeds are a staple of the pinyon jay’s diet. After gathering the nuts, the bird buries them for later use. Some seeds are inevitably forgotten, however, and forgotten seeds often grow into new trees. Thus, pinyon pines provide the jays with an important source of food, and the pinyon jays ensure a healthy population of pinyon pines, creating a wonderfully symbiotic relationship.
When viewed as a whole, the plants and animals of a particular area form unique, interdependent communities called “biotic communities.” From tropical rainforests to Arctic tundra, biotic communities are found in every environment in the world. In Grand Canyon, there are six major biotic communities: boreal forests, ponderosa forests, pinyon-juniper woodland, desert scrub, and the lush riparian habitat along the banks of the Colorado River. With the exception of the riparian habitat, these biotic communities generally form horizontal bands across Grand Canyon.
Because elevation has such a profound effect on climate, it seems reasonable to assume that the location of biotic communities could be based on elevation. Although elevation provides a rough approximation of where certain biotic communities might occur, many local environmental factors also come into play. Furthermore, many plants and animals live in more than one biotic community. In Grand Canyon, where a large number of biotic communities are packed tightly together, their boundaries become even more blurred.
Biotic communities are also affected by microclimates—small pockets of temperature and moisture that vary dramatically from their immediate surroundings. Microclimates are caused by a variety of environmental factors including local topography, proximity to water, and exposure to sunlight. South-facing slopes, for example, receive much more sunlight than north-facing slopes, making them significantly warmer and drier, even at higher elevations. This explains why desert plants such as yucca are found at high elevations on the south-facing North Rim, while shady pockets along the South Rim support small populations of Douglas-fir, a tree that generally avoids the South Rim’s warmer, drier climate.
Air currents also affect microclimates. During the day, as the sun beats down on the region, hot air rises up the Canyon walls. At night, by contrast, cool air flows down from the rim. These invisible rivers of air, flowing up and down the Canyon’s walls, allow a wide range of plants to survive in unlikely places in Grand Canyon.
Life zone boundaries are often blurred by Grand Canyon’s dramatic topography, but the Canyon also acts as a formidable barrier to plant and animal movement. Consider the Abert squirrel, a small grayish squirrel that is entirely dependent on ponderosa pines as a source of food. During the last Ice Age, when the climate was much cooler and wetter, ponderosa forests stretched across much of northern Arizona, including the Inner Canyon. For thousands of years, Abert squirrels roamed throughout the ponderosa forests in the Inner Canyon, but when temperatures started to rise around 10,000 years ago, the ponderosa pines retreated to higher elevations. Trees growing in the depths of the Canyon moved up to the rims, and with them came the Abert squirrels. Some squirrels retreated to the South Rim; others retreated to the North Rim, creating two distinct Abert squirrel populations on either side of the Canyon. Over time, the squirrels living on the North Rim developed unique physical characteristics (most notably a striking white tail) that have led scientists to classify them as an entirely separate subspecies called the Kaibab squirrel.
The interaction between plants, animals, and landscapes is incredibly complex in any environment. But in Grand Canyon, one of the most dynamic environments in the world, this complexity is elevated further. At times, it can be overwhelming. Even seasoned naturalists sometimes find themselves struggling to comprehend the sophisticated ecology of the park. But Grand Canyon also presents a tremendous opportunity for study and exploration. You could easily spend a lifetime learning about Grand Canyon’s ecology, which is what keeps many people coming back year after year.
Because Grand Canyon is located in the arid Southwest, it receives much less precipitation than most parts of the country. Although precipitation is minimal, it arrives in a fairly predictable pattern, falling in winter and summer in a nearly 50/50 split.
In the summer, prevailing winds arrive from the south, carrying moisture from the Gulf of California. As moist air passes over Arizona, it’s lifted up and over the highlands just south of Grand Canyon, arriving at the Canyon cool and condensed. In the morning, when the sun heats the Inner Canyon, hot air rises and collides with the cool, moist air above. This sudden collision creates short-lived afternoon thunderstorms. In July, August and early September (a period referred to as “monsoon season”), these storms pound Grand Canyon on an almost daily basis.
In the winter, prevailing winds arrive from the west or northwest, bringing moist air from the Pacific Ocean. The vast majority of this moisture is wrung out by the Sierra Nevada Mountains, but some does find its way into northern Arizona. Although winter storms in Grand Canyon are much less intense than summer storms, they often linger for days.
In the spring and the fall, Grand Canyon becomes extremely arid, resulting in dramatic temperature swings. Dry air allows up to 90 percent of solar radiation to reach the ground during the day. At night, however, the situation is reversed, and 90 percent of the Canyon’s accumulated heat radiates back into the atmosphere through clear, dry skies. In humid areas, by contrast, only 40 percent of solar radiation reaches the ground during the day, but that heat is often reflected back by an insulating cloud cover at night.
The concept of biotic communities, or "life zones," where specific groups of plants and animals interact, was first developed at Grand Canyon by the biologist C. Hart Merriam. In 1889 Merriam, then director of the U.S. Biological Survey (and a founding member of the National Geographic Society), led an expedition to Grand Canyon to study the region’s plants and animals. As he descended into the Canyon, he noticed distinct communities of plants and animals living together. He called these communities “life zones,” and theorized that their location was due to the varying temperatures. Additional research would show that life zones are dependant on much more than temperature, but Merriam’s Grand Canyon expedition was the first time plants and animals were studied living together in a quantifiable way. His groundbreaking work helped pave the way for the modern study of ecology.
Twenty thousand years ago, near the peak of the last Ice Age, Grand Canyon was a very different place. Although the topography was nearly identical, the distribution of plants and animals would be unrecognizable to modern eyes. In the depths of the Ice Age, a cool, wet climate descended over the Southwest, forcing many plants and animals to retreat to lower, warmer elevations. Juniper trees, which currently grow on the South Rim, grew along the banks of the Colorado River during the Ice Age, and Douglas-fir, a tree currently found only in the park’s highest elevations, grew on the Tonto Platform, 3,000 feet below the rim.
Many strange and wonderful creatures also roamed the region during this time, including mammoths, camels, and Merriam’s teratorn, a bird with a wingspan more than 12 feet across. Grand Canyon was also home to the Shasta ground sloth, a massive animal that stood six feet tall and weighed over 300 pounds. But around 10,000 years ago many of these large animals went extinct, most likely due to over-hunting by early human settlers.
As the glaciers that covered much of North America retreated between 15,000 and 10,000 years ago, the Ice Age drew to a close. In the Southwest, temperatures rose, the climate dried out, and plants and animals living in the Inner Canyon began a slow migration towards the rim. By about 8,500 years ago the inner canyon had been transformed from a woodland to a desert. The remarkable flexibility of Grand Canyon’s plants and animals—retreating to the Canyon’s depths when temperatures drop, climbing back to the rim when temperatures rise—is a powerful reminder that the park’s seemingly fixed life zones are, in fact, highly dynamic and adaptable.
The arrival of early human settlers from Asia coincided with the extinction of many large mammals such as horses, camels and sloths that once roamed Grand Canyon. Whether this "Ice Age Extinction" was due to over-hunting or previously unknown diseases arriving in North America remains a mystery. But once it was over, Grand Canyon's distribution of plants and animals remained relatively stable for thousands of years. In recent years, however, Grand Canyon has experienced many subtle—and not so subtle—changes.
The most notable change has been to the Colorado River. For thousands of years, the Colorado flowed free above Grand Canyon. Melting snow in the Rocky Mountains unleashed annual spring floods, and by winter the river's volume had slowed to a trickle. The temperature of the silty water also varied dramatically throughout the year. Over tens of thousands of years, a handful of fish evolved to survive in these unusual conditions. All told, eight fish species are native to Grand Canyon, and six of those species are endemic to the Colorado River Basin (found nowhere else in the world).
In 1963 Glen Canyon Dam was built just upstream of Grand Canyon. Almost overnight, the river's downstream ecology was completely altered. Instead of spring floods and winter trickles, the river now had a consistent, steady flow. And because the dam-released water was drawn from the dark, chilly depths of Lake Powell, it entered the Canyon silt-free and numbingly cold. The cold, clear water provided terrific habitat for non-native fish like trout that were introduced for sport, and since 1958 two dozen non-native fish species have been reported in Grand Canyon. But the introduction of non-native fish has been disastrous for native species. Non-native species compete with native fish for food and, in some cases, prey on native fish directly. To date, three native fish species have disappeared entirely from Grand Canyon, and two, the humpback chub and razorback sucker, are struggling to survive.
The humpback chub first appeared three to five million years ago. Because it evolved in swift muddy waters, it developed some remarkable biological adaptations. Large fins allow it to easily maneuver rapids, small eyes protect it from silt, and when swift water passes over its pronounced hump, the chub is forced down toward the bottom of the river where the current is less strong, helping it stay put during floods. Humpback chub thrived in the virgin Colorado, but its population in Grand Canyon plummeted after the completion of Glen Canyon Dam. Although humpback chub can survive in the cold, dam-released water, they need warm water to spawn. In 1967 the humpback chub was declared an endangered species, and today only a few thousand chub survive in Grand Canyon. Most of them live at the confluence of the Colorado River and the free-flowing Little Colorado River.
In 2009 the National Park Service began relocating juvenile humpback chub from the Little Colorado River to Shinumo Creek, a small tributary of the Colorado further downstream. A waterfall in Shinumo Creek prevents non-native species from entering the creek's upper reaches, thus providing a safe haven for the young chub. The establishment of a satellite population of humpback chub is critical for the long term success of the species. A hazardous materials spill in the Little Colorado River, for example, might otherwise prove disastrous. Although the relocation program is still in its infancy, initial results appear encouraging.
Dramatic changes in the Colorado River post-Glen Canyon dam have also affected the riverbank. Massive spring floods used to roar through Grand Canyon, scouring the riverbank and preventing many plants from taking root. Over the past several decades, however, the dam's steady, consistent releases have eliminated large floods, and a dense thicket of shrubs and trees has sprouted up alongside the river. (Although the presence of these plants is technically unnatural, they currently provide valuable habitat for the southwestern willow flycatcher, which is listed as an endangered species.)
Among the riverbank's new arrivals is tamarisk, a plant native to the Middle East that was brought to America as an ornamental in the late 1800s. Tamarisk is remarkably resilient, and it has spread like wildfire along rivers throughout the Southwest, arriving in Grand Canyon in the 1920s. In addition to muscling out native plants, tamarisk trees suck up vast amounts of water—up to 250 gallons per day. In 2000 the park service began cutting down tamarisk, and to date roughly 270,000 trees have been removed from the park. In 2001 the tamarisk leaf beetle, which feeds specifically on tamarisk, was intentionally released in the West, and by 2009 the beetle had made its way into Grand Canyon.
Non-native species have also affected Grand Canyon's vast rocky spaces. When miners abandoned their search for Grand Canyon riches in the late 1800s, they often left pack animals behind. Burros, originally from the deserts of Africa, were rugged enough to survive on their own, and soon they were breeding and multiplying. By the 1970s there were as many as 350 feral burros living in Grand Canyon. Conservation groups grew alarmed that the burros were competing with native bighorn sheep for scarce resources, and the burros were rounded up one by one and transported out of the Canyon by helicopter. Many feral burro populations remain throughout the Southwest, however, and in recent years there have been reports of new feral burro populations in western Grand Canyon.
In 1906 President Theodore Roosevelt established the Grand Canyon Game Reserve on the forested Kaibab Plateau just north of Grand Canyon. James Owens, who became known as "Uncle Jim," was appointed manager of the reserve, and from 1906 to 1918 he claimed to have shot over 600 mountain lions there. The walls of his cabin were covered with mountain lion claws, and a sign outside advertised, “Lions Caught to Order, Reasonable Rates.” At the time, mountain lions were considered vicious "varmints" with an insatiable appetite for wild deer and local ranchers' cattle. Exterminating such ruthless predators was considered both logical and necessary.
Between 1906 and 1924, however, the number of deer on the Kaibab Plateau exploded from 4,000 to 100,000. The deer soon outstripped the plateau's food supply, and over the next two years 60,000 deer died of starvation. Biologists concluded that the rapid rise and fall of the deer population was caused by the systematic reduction of mountain lions, which preyed upon deer and, it was argued, kept their population in check. The "Kaibab Deer Incident" became a fixture in biology textbooks, demonstrating how man's interference with nature can upset its delicate balance. The story of the Kaibab deer was referenced in both Aldo Leopold's A Sand Country Almanac and Rachel Carson's Silent Spring, two of the most influential environmental books of the 20th century.
Then, in 1970, the biologist Graeme Caughley challenged the basic assumptions of the Kaibab Deer Incident. He questioned the deer population data, which was determined largely through guesswork, and concluded that mountain lions played a relatively small role in regulating the deer population. Caughley argued that habitat changes caused by climate, ranching, and government policy had a far greater impact on the deer population than mountain lions. His conclusions gained wide acceptance, and references to the Kaibab Deer Incident were soon removed from many textbooks.
In recent years, however, Caughley's study has been challenged by biologists who believe that mountain lions did play a significant role in regulating the Kaibab deer population. The Great Kaibab Deer Debate, it seems, is far from over. Perhaps the ultimate lesson is that the natural world is often far more dynamic and complex than it appears at first glance. Despite all we have learned, our scientific understanding of nature is far from complete, and there is much that remains to be discovered.
With wingspans over nine feet across, California condors are the largest birds in North America. To see a condor in flight is a highlight of any trip to Grand Canyon. For decades, however, these magnificent birds were completely absent from the park. Thirty years ago, California condors sat at the brink of extinction with a worldwide population of just 22 birds. Thanks to a long-shot recovery effort initiated by biologists in the early 1980s, California condors are now making a remarkable comeback.
Although cursed with a face that only a mother could love, condors are extremely graceful in flight. Riding thermals, they can fly for hours without ever flapping their wings. Condors can soar as high as 15,000 feet, reaching top speeds of 50 mph and traveling hundreds of miles per day. In Grand Canyon, condors are often seen soon after sunrise or just before sunset. Although easily confused with turkey vultures, condors have much larger wingspans and triangular white coloring on the underside of their wings. Adult condors are characterized by a pink-orange head and a white underwing coloration. Young condors are almost entirely black. Mature condors weigh up to 23 pounds, and they can live 50 years or more.
California condors are scavengers that feed exclusively on carrion (the decaying flesh of dead animals). Their powerful bills can break bones and tear out flesh, and their bald heads allow the birds to dig deep into bloody carcasses without dirtying their feathers. Condors typically feed on elk, mule deer and cattle, but they eat just about anything they can find. Because the supply of carrion is unpredictable, condors eat as much as possible whenever they can. They store excess meat in their "crop," a fleshy extension of the esophagus, visible on the front chest, that can hold more than three pounds of meat.
California condors once ranged from Canada to Mexico. During the Ice Age, they feasted on the carcasses of large animals such as mastodons and giant sloths. When these animals went extinct roughly 10,000 years ago, California condors lost a major source of food, and their population started to decline. By the time European explorers arrived, condors were only found in western North America. When settlers arrived in the West, condor populations plummeted due to hunting, egg collecting, the ingestion of poisonous bait (left for coyotes), and the ingestion of poisonous lead shot from the carcasses of hunted animals. The condors' slow reproductive rate—they generally lay just one egg every two years—exacerbated the problem. By the 1940s, condors were only found in southern California.
By 1982 the worldwide California condor population had dropped to just 22 birds. In desperation, the L.A. Zoo and the San Diego Zoo began a captive breeding program. In 1987 biologists captured the last wild birds to ensure their safety. A year later, the first captive bred California condor hatched. The condor chick was fed using a condor mother hand puppet. This prevented it from growing accustomed to humans, a critical factor if the young condor was to someday fend for itself in the wild.
In 1992 the first captive-raised condors were reintroduced to central California. Four years later, condors were reintroduced to the Vermillion Cliffs in northern Arizona. Soon, condors were flying over Grand Canyon for the first time in over 70 years. Grand Canyon’s remote location, rugged terrain, and strong updrafts offer ideal conditions for condors. Over the next two decades more captive bred condors were released in the region. Then, in 2003, a wild-bred condor chick successfully fledged (left the nest) in Grand Canyon. It was the first time a wild condor had fledged anywhere in the world since 1982. As of this writing, seven wild-bred California condors were flying free in Arizona and Utah.
Today there are over 430 California condors, over half of which live in the wild. Arizona and Utah are home to over 70 condors. Although lead poisoning from spent bullets remains the biggest threat to wild condors, groups like The Peregrine Fund (peregrinefund.org) are working to ensure a bright future for these magnificent birds.
Peregrine falcons are birds of prey that can spot victims from thousands of feet above. They then dive bomb their targets at speeds topping 200 mph—the fastest speed of any animal. The collision creates an explosion of feathers. Victims that don’t die upon impact have their necks broken by the peregrine’s powerful beak. Peregrine falcons are such successful strikers that they were used to kill Nazi carrier pigeons in World War II. By the early 1970s, however, peregrine populations in the U.S. had declined due to hunting and the toxic effects of the pesticide DDT. To increase populations, young peregrines were raised in captivity and released in the wild. Today roughly 100 peregrine falcon pairs nest in Grand Canyon.
Famous for their striking white heads, bald eagles are large birds of prey with seven-foot wingspans. Their nests measure up to 10 feet across and weigh up to 2,000 pounds. Although designated America's national symbol in 1782, by the 1960s there were fewer than 400 nesting pairs of bald eagles in the lower 48 states. Hunting, habitat loss and the toxic effects of pesticides had decimated eagle populations. Today, after decades of conservation efforts, bald eagles have made a remarkable comeback. There are now over 20,000 nesting pairs in the lower 48 states.
This small brown and white songbird is famous for its beautiful call, a series of delicate high-pitched whistles that descend in speed and tone. Spend a week floating down the Colorado River and you'll soon learn to recognize the canyon wren's delightful song. Males sing to defend their nesting territory. Canyon wrens are found in the arid mountains and canyons of the West. Their range stretches from British Columbia to southern Mexico. Their long, narrow bill is used to pluck insects and spiders from small openings and rock crevices.
Turkey vultures are often mistaken for California condors in Grand Canyon, but they have white feathers at the outer edges of their wings—the opposite coloration of California condors. In addition, turkey vulture wingspans measure "just" six feet across. But condors and turkey vultures do share many similarities. Both are scavengers that feed on carrion (dead animals), and their bald, featherless head is easy to clean after poking around a bloody carcass. Turkey vultures range from Canada to Argentina, and their population is estimated at roughly 4.5 million birds. Adult turkey vultures weigh up to five pounds. They can live up to 16 years in the wild.
Ravens are opportunistic omnivores that eat insects, nuts, small animals, dead animals and garbage. Highly adaptable, they are found from the river to the rim in Grand Canyon, making them one of the park’s most commonly spotted birds. Although often mistaken for crows, ravens are significantly larger. They weigh up to 3.5 pounds with a 50-inch wingspan. Ravens have one of the largest brains of any bird. They make over 30 calling noises, including their famous kraaak-krah. Highly acrobatic, they can fly upside down and perform flips and rolls in flight.
These beautiful owls, one of three spotted owl subspecies in North America, are officially listed as endangered. Mexican spotted owls are among the largest owls in North America, growing up to 19 inches long with a nearly four-foot wingspan. Adults weigh up to 1.5 pounds. Their range stretches across the Four Corners region to western Texas and central Mexico. In northern Arizona they often nest in rocky canyons. Mexican spotted owls hunt small mammals at night. Their large eyes provide superior vision in low light, but unlike most owls Mexican spotted owls have dark eyes.
Bighorn sheep are among Grand Canyon’s most impressive animals. Well adapted to steep terrain, they can traverse two-inch ledges, scramble up steep slopes and jump down 20-foot inclines with grace. Their unique concave hooves, which feature a hard outer edge and soft interior sole, help them grip rocks and navigate cliffs. Sharp eyesight and keen hearing help them detect predators such as mountain lions, coyotes and bobcats.
The ram’s legendary horns take up to a decade to grow, curving up and over the ears in a C-shaped curl. A large pair of horns can weigh up to 30 pounds and reach 30 inches in length. During mating season, competing rams charge each other head on at speeds topping 20 mph. When rams collide, their horns smash together, producing a loud cracking sound that can be heard for miles. Thickened skulls allow rams to withstand repeated collisions. Rams can fight for over 24 hours, and those with the biggest horns generally do the most mating.
Bighorn rams weigh up to 220 pounds. Ewes weigh up to 160 pounds. Both rams and ewes develop horns shortly after birth, but ewe horns are skinny and never grow past half curl. Ewes generally stay with their family herd. Adult rams, by contrast, live largely isolated lives.
Desert bighorn sheep (Ovis canadensis nelsoni), which are found in the deserts of the U.S. and Mexico, are a subspecies of bighorn sheep found in much of the West. Well adapted to arid environments, desert bighorns can survive for weeks without water. Grasses constitute the majority of their diet, but they also eat sedges and cacti. Adults can live up to 20 years in the wild. From 1850 to 1950, desert bighorn populations plummeted due to hunting and diseases from domestic sheep. Since 1960, however, desert bighorn numbers have increased substantially thanks to successful conservation measures.
Mountain lions (also known as pumas or cougars) are found from Canada to Argentina—the most extensive range of any mammal in the Western Hemisphere. Historically they inhabited all 48 lower U.S. states. In the late 1800s and early 1900s, however, mountain lions were hunted to the brink of extinction. Following the enactment of strict hunting regulations, they have made a steady comeback in the West, and today they are slowly spreading east.
Mountain lions are the second-largest wildcats in the Western Hemisphere after jaguars. Males weigh up to 250 pounds and measure more than eight feet in length. Females weigh up to 140 pounds and can measure up to seven feet in length. Mountain lions have proportionally the largest hind legs of any feline. They can jump nearly 20 feet vertically, 30 feet horizontally, and reach top speeds of 50 mph. Retractable claws aid in both hunting and tree climbing.
Mountain lions travel up to 25 miles a day in search of food. One mountain lion in Grand Canyon descended the South Rim, swam across the Colorado River, and climbed to the North Rim in a span of eight hours. Mountain Lions are quick, efficient hunters, quietly stalking prey before pouncing. Victims often die from a lethal bite to the spinal cord. In Grand Canyon mountain lions feed primarily on mule deer, killing up to one per week. They also prey on elk, coyote and bighorn sheep.
Solitary and territorial, mountain lions require an extensive "home range." In Grand Canyon the home range can measure up to 185 square miles. Adult mountain lions come together only to mate. Females are exclusively responsible for parenting, and cubs stay with their mother for roughly two years while she teaches them survival skills. Mountain lions are born with a spotted coloration. They develop a uniform tan coloration by about 2.5 years in age.
Reclusive by nature, mountain lions go to great lengths to avoid people. Sightings are uncommon, and attacks on humans are extremely rare. If you do encounter a mountain lion in Grand Canyon, slowly back away while holding a steady gaze.
Elk are the largest member of the deer family on the Colorado Plateau. Male elk (bulls) grow up to eight feet long and weigh up to 800 pounds. Female elk (cows) grow up to seven feet long and weigh up to 500 pounds. After moose they are the second-largest member of the deer family in North America. The name "elk" was derived from a European word for moose because early explorers thought the two animals looked similar.
Elk are distinguished from mule deer by their massive size and unique coloration: a tan body with a dark brown "pelage" (coat) above the neck. Shawnee Indians call elk wapiti, “White Rump,” due to their white backside.
In the fall, massive antlers are an elk’s most prominent characteristic. Antlers, which grow only on bulls, can reach four feet in length and weigh up to 40 pounds. They are shed each spring, and over the next three to four months new antlers grow back at the rate of about one half inch per day. Antlers reach maximum size in time for the rut (mating season). During the rut, which generally lasts from late summer to mid-November, bulls emit a bugle-like sound as a sign of dominance and a challenge to other bulls. The bugle starts off as a bellow and changes to a shrill scream. It can often be heard for miles. Dominance between bulls is determined in contests where bulls engage in antler wresting. The most dominant bulls assemble a harem of a dozen or more cows, which then give birth in the spring
Elk are ruminants with four-chambered stomachs. They forage on grasses, plants, leaves and bark. On average, elk eat about 20 pounds of vegetation a day. In Grand Canyon elk are often seen grazing near Grand Canyon Village. Although they have become accustomed to humans and appear docile, elk should never be approached, especially during the rut.
In the early 1900s, elk were eliminated from the Southwest due to over-hunting. The elk now found in Grand Canyon are descendents of elk transplanted from Yellowstone National Park between 1913 and 1928.
Mule deer are named for their large ears, which move independently of each other like those of a mule. Common throughout the western U.S., their range extends from western Canada to central Mexico. Adult mule deer are five to seven feet in length. Bucks weigh 150 to 300 pounds. Does weigh 95 to 200 pounds.
Mule deer are ruminants with multi-chambered stomachs. In the summer they forage on plants, leaves and brushy vegetation. In the winter they forage on conifers such as juniper and ponderosa pine.
Although closely related to white-tailed deer, mule deer are slightly larger. Mule deer have white tails with a black tip, and their bifurcated antlers “fork” as they grow. (White-tailed deer antlers, by contrast, branch from a single main beam.) Bucks grow a large pair of antlers each year, then shed them each winter. The annual cycle of antler growth and shedding is regulated by changes in the length of the day.
During the fall rut (mating season), bucks compete for females. Although conflict between bucks is infrequent, mild fights sometimes break out. Fighting bucks enmesh antlers, then try to force the head of the other buck down. Although injuries are rare, antlers sometimes become locked together. If the two bucks cannot unlock their antlers, they will be unable to eat, and both will ultimately die of starvation.
After breeding in the fall, gestation lasts 190 to 200 days. Young does give birth to one fawn. Older does often give birth to twins. Fawns are born with white spots on their backs, which help camouflage them with the dappled light of the forest floor. As fawns grow older, the white spots disappear. Fawns are able to distinguish their mother through a unique odor produced by glands on the mother’s hind legs. Fawns stay with their mother until they are weaned in the fall. Conflict between does is common, so family groups tend to be spaced widely apart.
Adult mule deer live up to eleven years in the wild. Predators in Grand Canyon include mountain lions, bobcats and coyotes.
Bobcats are North America’s most common wildcat. Their range extends from Florida to the desert Southwest, but they are highly elusive animals. They typically spend the day resting, then search for prey around dusk or dawn. Their diet includes a wide range of small animals such as rabbits, squirrels, birds and snakes. Bobcats rarely chase their prey, however, preferring to seek out a hiding spot and lie in wait. When a victim approaches, the bobcat pounces, snagging its prey with sharp, retractable claws. The name “bobcat” comes from the cat’s stubby “bobbed” tail. Bobcats share many personality traits with house cats, including hissing, purring and using trees as scratching posts. Like most felines, bobcats are largely solitary. Males and females come together only to mate. Females generally have litters of two or three kittens. Those that reach adulthood typically live six to eight years in the wild. Adult bobcats weigh an average of 20 pounds.
Historically confined to the open spaces of the West, coyotes greatly expanded their range following the extermination of wolves in the 1800s. Today coyotes are found throughout most of North America. Intelligent and adaptable, they live in all of Grand Canyon's ecological zones, from the deserts at the bottom of the Canyon to the spruce-fir forests on the North Rim. Coyotes typically hunt in pairs, and they can reach speeds topping 43 mph. Their diet consists mostly of small mammals, but coyotes eat just about anything, including birds, snakes, insects and trash. Adult coyotes weigh up to 30 pounds. In the winter, their brownish-red coat turns grey. In native legends Coyote is often portrayed as a scheming, meddling trickster who scrapes by on cunning and charm. The word “coyote” is derived from the Nahuatl (Aztec) word cóyotl. Coyote’s Latin name, Canis latrans, means “barking dog.”
Grand Canyon Rattlesnakes are one of six rattlesnake species in Grand Canyon. A subspecies of Western Rattlesnakes, Grand Canyon Rattlesnakes evolved over millions of years in the depths of Grand Canyon. Today they are only found in Grand Canyon. They are distinguished by pale, pinkish coloration and irregular dark blotches with a pale center. Like all rattlesnakes, Grand Canyon Rattlesnakes have poor eyesight but a sharp sense of smell. They can detect body heat through infrared sensors located on either side of their head. These keen senses are used to detect prey while a rattler lies in wait. When a rattler strikes, it injects a paralyzing venom through sharp fangs. When the victim is motionless, the rattler swallows it whole. Rattlesnakes, in turn, are preyed upon by eagles and hawks, which pluck rattlers from the ground and drop them repeatedly from the air.
These beautiful squirrels are found only in the ponderosa pine forests of the Kaibab Plateau, an area measuring roughly 20 miles by 40 miles alongside Grand Canyon's North Rim. In behavior and biology, Kaibab squirrels are nearly identical to Abert's squirrels, which are common on the South Rim. But whereas Abert's squirrels have a white belly and a gray tail, Kaibab squirrels have a dark belly and a white tail. Scientists believe long ago both squirrels belonged to the same species. As global temperatures fluctuated during the Ice Age, however, ecological zones shifted and an isolated squirrel population was confined to the Kaibab plateau. Over time that population evolved into a distinct subspecies. Both Kaibab squirrels and Abert’s squirrels depend on ponderosa pines as a major source of food, eating the tender bark and seeds from the pine cones.