The Sonoran Desert

The Sonoran Desert covers over 120,000 square miles across two countries and several Native American Nations. It lies between the Mohave Desert to the north and west and the Chihuahuan Desert to the south and east. It is bounded by the Mogollon Rim on the northeast, the Chiricahua and Pinaleño Mountains in the east, and the Sierra Madre Occidental in the southeast. The geographical boundaries reach from the southeastern part of southern California, across the western two thirds of southern Arizona, into northwest Sonora, Mexico, and the eastern shore of the Baja California peninsula, including the islands of the Sea of Cortez. The elevation of the Sonoran Desert ranges from approximately 200 feet to nearly 4,000 feet above sea level.

Biomes, or major ecological community types, do not have strictly defined borders. Rather they have transition zones from one biome to another, called ecotones. These ecotones contain animal and plant diversity from adjacent ecological communities. Several national parks lie in the ecotone between the Sonoran Desert and higher elevation grassland and woodland communities including Tuzigoot National Monument, Tumacácori National Historic Park and Montezuma Castle National Monument.


One characteristic that differentiates the Sonoran from other North American deserts is the presence of leguminous trees and large columnar cacti, which results from bimodal rainfall. Bimodal rainfall means two rainy seasons, and in the Sonoran Desert, one occurs in summer, with storms coming from the southeast, and one in winter, with storms coming from the west. On average, Sonoran Desert areas receive between 3 and 15 inches of rain per year, divided between the summer and winter rains. Summer “monsoon” rains are preceded by a shift in prevailing winds, and vigorous storms dump large amounts of rain over short time periods. Dry ground does not always soak up all the moisture. Summer pulses of standing and running water are often essential for the survival of Sonoran Desert plants and animals. For instance, Sonoran desert toads (Bufo alvarius) hibernate until heavy rains form pools where they can lay their eggs. Winter rains that occur from December to March are steady and gentle. The water soaks into the ground and does not usually cause flooding. Another Sonoran Desert distinction is its mild winters. Hard freezes experienced by other North American deserts are rare which, along with the summer rains, allow perennial plant species that are partly tropical in origin to survive. Over half of the plant species found in the Sonoran Desert are annuals, whose populations are supported by the mild winter rainy season. In comparison, the Mohave and Chihuahuan Deserts have unimodal rainfall, or one major rainy season, and frequent hard winter freezes. This regime promotes growth of low shrubs instead of trees and succulents.



The Sonoran Desert has not always appeared as it does today. About 8 million years ago in the Middle Miocene Era, this region was wet, woody tropical deciduous forest. Decreased amounts of rainfall led to a drying trend that allowed thornscrub to establish along the edges of the forests, creating a transition zone between tropical deciduous forest to the south and the Sonoran Desert. Woodland trees and shrubs moved into this area in the late Pleistocene (45,000-11,000 years ago) due to greater winter rainfall and less summer moisture. The most recent expansion of the Sonoran Desert occurred around 9,000 years ago when woodland plants moved to higher elevations. Familiar desert plant species (paloverde, desert ironwood, organ pipe cacti) moved north about 4,500 years ago.

Humans have lived in the Sonoran Desert for at least 12,000 years. Resident tribes, including the Hohokam, Cocopas, Yaqui, Mohave, and Upper Pimas, used the landfor agriculture. Some tribes developed elaborate irrigation systems to water their crops, while others used receding floodwaters. Other tribes, such as the Seri Indians, do not farm because they live in one of the driest areas of the Sonoran Desert on the coast of Sonora, Mexico. They still sustain themselves by gathering wild plants, hunting animals and birds, and fishing.

When the first Europeans came to the southwestern U.S. in the 1500s, they brought with them new varieties of crops, new animals and tools that aided in agriculture and transportation, and new religious practices. They also brought diseases that spread throughout many of the Indian tribes. The Indians had no genetic resistance to measles, influenza, or smallpox, and within two centuries their numbers in the Sonoran Desert region had decreased by as much as ninety-five percent.


The Sonoran Desert lies in a region known as the Basin and Range geologic province, which is characterized by long, parallel mountain ranges that are isolated from each other by intervening valleys of grassland or desert. A major period of volcanic activity occurred in the Sonoran Desert area between 20 and 40 million years ago. There were many active volcanoes that produced large calderas, lava vents, and cinder cones. These features can be seen on the landscape today. Depending on the location, the soils can either support or hinder plant growth, giving them an important role in the Sonoran Desert’s environment.

Basin and Range Topography

The Sonoran Desert lies in a region known as the Basin and Range geologic province, which is characterized by long, parallel mountain ranges that are isolated from each other by intervening valleys of grassland or desert. In the Sonoran Desert, the complex portion of basin and range topography is also called the “sky islands.” The elevation of the basin and range topography varies from as low as 141 feet (Yuma, Arizona) in the basins to over 8,000 feet (Mount Graham in Arizona) in the mountains. To understand the processes that formed this topography, one must look beyond mountains or valleys that make up the basin and range. Stretching of the earth’s crust created faults that allowed plates of land to move over and under each other. This force pushed mountains up and dropped valleys down. The exposed rock of the uplifted mountains was then subjected to extreme weather and erosion, which caused mud, vegetation, and rocks to be carried rapidly down the mountain canyons. This sediment is deposited at the base of the mountain forming an alluvial fan, also known as a bajada. The repeated stretching, eroding, and depositing create the pattern of the basin and range.



A major period of volcanic activity occurred in the Sonoran Desert area between 20 and 40 million years ago. There were many active volcanoes that produced large calderas (circular basins formed by volcanic explosions), lava vents, and cinder cones. Rhyolite and basalt volcanoes characterize Sonoran Desert volcanism. The majority of the rhyolites were produced 20 to 40 million years ago, although some date back to at least 70 million years ago. Rhyolites are light-colored volcanic rocks rich in silica, aluminum, potassium, and sodium. Rhyolite volcanoes have a tendency to explode violently. The Tucson Mountains located on the western edge of Tucson, Arizona, consist of rhyolite volcanic rock from a volcanic episode 70 million years ago.

Basalts are younger rocks formed during the basin and range period within the last 10 million years. Basalt is dark-colored and rich in iron, magnesium, and calcium. Unlike rhyolite volcanoes, basaltic eruptions are non-explosive. They produce thick, oil-like lava that spreads across the floors of the valleys. The Pinacate field just south of Organ Pipe Cactus National Monument and north of Puerto Peñasco, Sonora is the most famous of the three basalt fields found in the Sonoran Desert.



The Sonoran Desert supports many types of soils that promote or hinder plant growth depending on location. In places that lack flowing or ground water, soils have a lower organic matter content. In contrast, soils in the Gila and Salt River valleys sustain rich vegetation and agriculture. In the desert basins, soils may be gravelly, sandy, or made up of clays, which can be gray and poor in humus or reddish and rich in lime. In central Arizona, brownish clays and sandy loams mask granite rocks. Within granite rocks and soils a unique mineral deposit called caliche can be found.

Caliche is a white to reddish-brown layer of deposit found underground in many soils formed when mineral-rich water flows through the soil, leaving calcium carbonate precipitates behind. As the calcium carbonate deposit hardens it forms layers, and, with time, erosion can leave hollow spaces in the earth where animals, such as the desert tortoise, can escape from the heat of the Sonoran Desert. Caliche can also bond to a wide variety of materials and was used by prehistoric people as a structural material in buildings.


Plants of the Sonoran Desert

The Sonoran Desert is considered lush compared to other deserts of the world. The defining characteristic that makes this desert lush is the greater than 10 inches per year of rainfall some areas receive. The Sonoran Desert has two rainy seasons, or bimodal rainfall. Bimodal rainfall allows for the growth of two dominant forms of plants that distinguish the Sonoran Desert from the other North American deserts: legume trees and columnar cacti. The biologically rich Sonoran Desert region supports many species of plants. Species native to desert regions have special adaptations that let them deal with low water availability. Plants use water sparingly and conserve water for periods of drought. For example, cacti have leaves or stems that are very thick and fleshy, and can hold a lot of water while losing very little through evaporation. Small hairs help shield the leaves and stems of some plants from high temperatures by deflecting sunlight from the plant surface.

Saguaro, The Giant Cactus (Carnegiea gigantea)

The saguaro cactus is a widely recognized symbol of the Sonoran Desert. The saguaro’s large white bloom is the Arizona state flower. The saguaro can live for up to 200 years, and can grow as high as 50 feet. The giant saguaro is found as high as 4,500 feet on south facing slopes in the Sonoran Desert. The cactus often will be found growing near other plants such as the triangle-leaf bursage, creosote bush, or paloverde tree. These plants provide shade for young saguaros and are known as nurse plants. Nurse plants provide protection for the saguaro in early growth stages, until eventually, the cactus outgrows the need for protection. The saguaro is a good provider for desert dwellers. In June or July, when the fruit is ripe, the white-winged dove (Zenaida asiatica) can often be seen eating seeds from the bright red fruits. The lesser long-nosed bat (Leptonycteris curasoae yerbabuenae) feeds on the flowers of columnar cacti, including the saguaro, as it migrates from south central Mexico to southern Arizona. The fruit has provided subsistence in the long dry months to humans and animals alike, and in early times the O’odham peoples used saguaro skeletons as building materials. Today, the fruit is still harvested annually and preserved, eaten fresh, or fermented for a sweet intoxicating beverage.


Lifecycle of a Saguaro

Saguaro flower buds can be seen around April at the top of the trunk and arms. In late May and early June white flowers open in the middle of the night and close the following day. Bats, birds, and insects help to pollinate the flowers of the saguaro. After the flowers are pollinated they turn into fruits which ripen within 30 or 40 days.

At the end of the ripening period the fruits begin to split open. Inside the red fleshy tissue are over 2000 tiny black seeds. Some are eaten by bats and birds that disperse the seeds to new locations, while others fall to the ground and are eaten by ground dwellers, such as the javelina. The wind also carries seeds. If the conditions are right the seed will germinate.

Out of 2000 seeds, only a handful will turn into a saguaro. Drought can postpone germination, seeds may not land near a nurse plant, and baby saguaros can be trampled by wildlife or eaten. The seeds that do make it rely on nurse plants, like mesquite and paloverde trees. Nurse plants offer shade and moisture necessary for the saguaro to grow.

Growth of the saguaro is slow. They do most of their growing during the summer rainy season. Around 65-75 years of age the saguaro will start to grow limbs off the main trunk. More arms allow for more flowers which help produce even more seeds aiding in the survival of the saguaro. At 125 years of age a saguaro is considered mature.

An average lifespan can be from 150-175 years of age or possibly longer. At this point a saguaro can be about 50 feet tall and weigh over 10 tons. Saguaros die of many causes-sometimes old age, but also because of lightning, strong winds, and animals. But even after a saguaro dies it’s ribs are used for food and shelter by many small animals.


Triangle-Leaf Bursage (Ambrosia deltoidea)

The triangle-leaf bursage is a low shrub found throughout the Sonoran Desert region. It sometimes shades and protects cacti, such as the saguaro, which soon outgrow the bursage and can cause its death. The triangle-shaped leaves and small yellow flowers make this plant easy to recognize, and its burs can grip with small curved spines to fur and clothes alike, allowing an efficient if somewhat bothersome dispersal system. It is usually one of the first plants to colonize hot, dry expanses where other plants cannot grow due to its tolerance for heat and direct sunlight and highly efficient water use. This plant is considered one of the desert’s nurse plants, creating valuable resources and shelter for many desert dwellers.


Paloverde (Parkinsonia spp. )

The paloverde is a member of the pea family (Fabaceae) with green, smooth bark, spiny branches, bright yellow and orange flowers, and abundant seed pods. The leaves are small and generally oval, and either protrude off branches or hang in rows on long, flexible stems. Three paloverde species can be found between 500 and 4,000 feet in the U.S.: the blue paloverde, (Parkinsonia floridum) named so because of its greenish-blue foliage, the foothill paloverde (Parkinsonia microphyllum), which has a greenish-yellow bark and small leaves, and the Mexican paloverde (Parkinsonia aculeata) found just north of the U.S.-Mexico border. Blue and Mexican paloverde trees generally grow along watercourses. A fourth species, palo brea (Parkinsonia praecox) occurs in Sonora, Mexico and Baja California Sur.


Brittlebush (Encelia farinosa)

Widely spread throughout the southern regions of the Sonoran Desert, generally below 3,000 feet, the brittlebush is a short shrub with gray-white leaves that grows between 3 and 5 feet tall, and has showy clusters of small yellow flowers, similar in appearance to sunflowers or daisies. The bush is highly resinous (it exudes a waxy, oily coating from the leaves and bark to help protect it from heat and water loss), and was used as incense in the churches of Baja California. The stems exude a gum that was chewed by Native Americans, and is traditionally used as a mouthwash for tooth or gum pain. During periods of drought the brittlebush will drop its leaves and replace them with smaller ones to reduce water loss. This plant is often seen growing along highways and washes, and is a hardy desert dweller.


Creosote Bush (Larrea tridentata)

Creosote bushes cover thousands of square miles of the Chihuahuan, Sonoran, and Mohave deserts below 5,000 feet. The plant’s strong, pungent odor predominates in many regions after a rain. The creosote bush has small, resin-covered (a waxy, oily coating) leaves packed with oil that gives them their distinctive smell. The bushes burst into bloom following adequate rain with small, yellow flowers, and eventually, white, fuzzy seed pods form and disperse on the wind or passing creatures. Many animals, such as lizards and rodents, use the creosote as a shelter, burrowing under the laterally extensive root system. The Gila monster (Heloderma suspectum) feeds on its leaves and flowers, and in areas where the creosote is cleared or burned, the lizards are less abundant.


Fremont Cottonwood (Populus fremontii)

This cottonwood thrives near streams and rivers in elevations up to 6,000 feet, but is common in lower riparian areas throughout the Sonoran Desert. The trees can grow between 40 and 80 feet high, and have long, flat, wedge-shaped green leaves in the early spring through late fall. They are usually found wherever there is a high water table and soil that is easy to penetrate. Sadly, the dropping water table in some parts of the Sonoran Desert region is taking a toll on the cottonwood. As the populations of cottonwood dwindle, so do food and shelter for migrating bird species, which use the southwest rivers as migration corridors. Birds must search longer and fly farther for the things they need, and the wetland and river habitats which were once plentiful are now crowded during migration season.


Mesquite (Prosopis spp.)

There are three species of mesquite in the Arizona portion of the Sonoran Desert and two additional species in Baja, California. The mesquite has a dual rooting system, an adaptation that allows this hardy tree to flourish. The taproot gathers deep water while a spreading root system lies just beneath the ground and gathers light rains at the surface. The mesquite has traditional uses as a source of food, fuel, and shelter for desert denizens. In the Sonoran Desert, the mesquite grows generally along drainages and in low-lying areas, and sometimes forms small forests (bosques), which provide welcome shade from the desert sun.


Ironwood Tree (Olneya tesota)

Known in Mexico as palo-de-hierro, this tree gets its name from its heavy, hard wood. The tree is browsed by bighorn sheep, deer, cattle, and smaller mammals. The seed is covered by a hard coating and is a favorite food of rodents. Early peoples used the wood extensively for firewood because it is so dense that it burns very slowly. It is usually found around 2,500 feet throughout the warmer, drier parts of the Sonoran Desert. The tree, at an average height of about 30 feet, has beautiful purple and white flowers, bluish green leaves, and a fissured trunk and branches with thin, scaly bark.


Desert Agave (Agave deserti)

The desert agave is found from 500 to 4,000 feet in the Sonoran Desert. It has large, succulent, spiny leaves that form a rosette. The agave is sometimes called the “century plant” because the plant takes a very long time to bloom. It does not take a century, however. Most flower after they have reached 8-20 years of age. To attract pollinators, the agave uses all of its energy, stored as sugars, to put up a long stalk that can reach up to 40 feet. After agaves pass the reproductive stage, they die because all of their energy has been expended. Desert agave flowers are large and showy, with bright yellow tufts of slim, tubular flowers covered in pollen.

In Mexico, other agave species are used to produce intoxicating beverages called mescal, tequila, and pulque. The “heart” of some agaves was also roasted and used for food by native peoples. The agave is an important food source for the Mexican long-tongued bat (Choeronycteris mexicana) as well. This bat and the agave have a mutually beneficial relationship. When the bat feeds from the flowers with its long tongue, pollen from the agave sticks to the bat’s head. As the bat moves to feed on other flowers, pollen is transferred and the plants are pollinated.


Jojoba (Simmondsia chinensis)

The jojoba (hoe-HOE-ba) is found in the southernmost areas of the Sonoran Desert above 1,000 feet in elevation. It is an evergreen shrub that grows to around 5 feet at maturity, and has leathery green leaves and small bell-shaped, light green flowers. The leaves provide valuable fodder for many animals, such as mule deer ( Odocoileus hemionus ), since the plants only lose their leaves during periods of severe drought. The small, hard fruits, sometimes called goat nuts, deer nuts, or quinine nuts, resemble small acorns. They are somewhat toxic and eaten mostly by squirrels and rodents. The native Seri people only ate the fruits of the jojoba during periods of extreme stress; however, they used the paste of the beans as a salve for burns. The fruits of the jojoba contain around 40% liquid wax (usually called “jojoba oil”), which is a high-quality lubricant important for industrial use. Jojoba oil also has a light, somewhat fruity, odor, and it is often used in cosmetics and soaps.


Boojum Tree (Fouquieria columnaris)

This strange looking plant gets its name from a mythical creature in Lewis Carroll’s poem The Hunting of the Snark. In 1922, Godfrey Sykes, a plant explorer, saw this plant and knew it had to be Carroll’s boojum. The boojum tree is a stem succulent, which means its trunk has special tissues that can store moisture. It has a single, tapered stem, or trunk, that can grow up to 60 feet tall with grayish-white bark and thin, pencil-like branches growing out from the stem. The branches grow rounded leaves in the presence of rain, but quickly drop these leaves during dry times. The trunk typically branches at the top and sometimes these branches can twist into strange shapes. A creamy white flower blooms at the tips of the trunk in July and August. The boojum tree is found on the Baja California peninsula of Mexico and on the west coast of the Mexican mainland in the state of Sonora. The boojum tree grows on rocky hillsides and alluvial plains, which are areas of clay, silt, sand, or gravel that are deposited by running water. Boojum tree stems are made of weak wood that can be easily damaged by hurricanes. However, this tree can live for 100 years up to possibly 300 years. The Spanish common name for the boojum tree is cirio. The cirio is a slender type of altar candle used in religious ceremonies and appropriately fits the description of the boojum tree.


Prickly Pear (Opuntia phaeacantha)

A cactus seen in more places than just the desert is the prickly pear. Living for 30 or more years, various species range from southern Canada to southern South America in arid deserts, tropical woodlands and high mountains. Stems or pads of the prickly pear grow in distinctly jointed flattened segments. These joints continue to grow until the dry season begins. New growth begins with a new pad. Whether or not they have spines, they have glochids which are tiny barbed spines that are very sharp and brittle. They are easily detached by anything that touches them. Prickly pears produce very colorful flowers. The fruit, called tuna in Spanish, ripen to purple and red in July and August and are an important food source for both humans and desert animals.


Organ Pipe Cactus (Stenocereus thurberi)

Organ pipe cactus may be identified by its numerous columnar, gently curving stems which all arise from a central point at ground level. Unlike the saguaro cactus, the organ pipe cactus rarely forms branches. The stems generally reach 9 to 11 feet in height but may exceed 20 feet. The white-to-lavender (or pink) flowers appear during the night along the tips and sides of the stems during much of the spring and summer. The young fruits are spiny, but as they mature, they burst open to reveal an internal red pulp. The very tasty fruits are harvested by Native Americans for both local and commercial use. It is better to eat these fruits with a spoon, to avoid pricking your hands on the spines.


Buckhorn Cholla (Opuntia acanthocarpa)

Named for the forked branches resembling deer antlers, buckhorn cholla might easily have been named adaptable cholla. Throughout its range of the northern Sonoran and Mojave deserts, a buckhorn's characteristics vary with almost every mountain range and valley population. Living on rocky and sandy slopes to 4000 feet in elevation, a buckhorn's branching stems spread the plant to ten feet across. With an average height of three feet, buckhorns appear bushy with many thin branches. The stems, light to dark green, grow six to ten inches long. As with many cacti, the stems are tinged with red or purple during drought or cold weather, responding to stress. Eight to twenty spines grow out of the stems' easily visible knobs or tubercles. These spines, about 3/4 to 1-1/2 inches long, are dark brown and covered with thin straw-colored sheaths. Flowers begin opening in spring and vary in color, many times within the same local population. Fruit of tan to brown appears soon afterward. At maturity, the fruit has many tubercles and is covered with long, barbed spines. Chollas are not a preferred nesting area for birds due to the openness of the branched stems and the fewer number of spines. Many native people prefer to eat the buckhorn's flower buds over those of other chollas.


Ocotillo (Fouquieria splendens)

The ocotillo is one of the oddest and most distinctive plants of the southwestern deserts. The plant is a woody shrub composed of several long, thin, unbranched stems that arise from a very short trunk. Despite its heavily thorned stems, this plant is not a cactus. Ocotillo leaves appear in the spring after the winter rainy season and are dropped to conserve moisture when the soil dries out. Heavy summer rains can break this semi-dormant period, causing the plant to come into full leaf again within a few days. This water-conserving cycle may reoccur several times during a single growing season. The spectacular flowers of the Ocotillo appear in the spring, as dense spikes of bright red blossoms produced at the stem tips. This brilliant display has given rise to common names such as candlewood and flaming sword.


Wildlife of the Sonoran Desert

The Sonoran Desert is home to a huge number of animal species. The desert supports over five hundred species of vertebrates and innumerable invertebrates. The area around Tucson, Arizona is home to over one thousand species of bees alone!

The Sonoran Desert is a complex ecosystem that is at times hot, dry, and dangerous for its native animals and yet it is still home to many wildlife species. Animal adaptations help them obtain food, build homes, withstand weather and attract mates. For example, kangaroo rats (Dipodomys spp.) have no need to drink water because they can obtain their water from seeds and vegetation that they ingest. Other animals have physical adaptations as well. The jackrabbit has very large ears with many blood vessels that help to release body heat.

Many animals are nocturnal, restricting all their activities to the cooler temperatures of the night. Bats, many snakes, most rodents, and some larger mammals like foxes and skunks, are nocturnal, sleeping in a cool den, cave, or burrow by day. The Gila woodpecker has developed a way of burrowing into large saguaro cacti to make a home while also not harming or killing the cactus. These adaptations come from actions that the animals take, and are known as behavioral adaptations.


Javelina (Tayassu tajacu)

Range: From Argentina to Texas, New Mexico, and Arizona.
Size: 40-55 pounds and 20-24 inches tall; size of a medium dog

The javelina or collared peccary is the only wild, pig-like animal in the United States, but is not a true pig. The javelina is a stout animal weighing between 35 and 60 pounds, with a large head, heavy snout, razor-sharp tusks, thick coarse hair, and poor eyesight. Javelina emit a strong musky odor and usually can be identified by smell before sight. The javelina average lifespan in the wild is 7.5 years and they live and forage in herds of 8-20 animals, primarily eating agave and prickly pear. They are most active in late evening or early morning. Javelina are not dangerous animals, but are very protective of their herd. They have been known to attack dogs, coyotes and bobcats. In some places in the Sonoran Desert, javelina is considered a game animal and is actively hunted during designated seasons.


Gila woodpecker (Melanerpes uropygialis)

Range: southern half of Arizona, southeastern California, southwestern New Mexico, Baja and western Mexico.
Size: about 8 inches long

The Gila woodpecker is a medium sized bird with a dark tan head and a heavily black and white barred back, while only the adult males have a small, red cap on top of their heads. This woodpecker feeds on insects, bird eggs, fruits, and berries. It makes holes in columnar cacti, such as the saguaro, 15-25 feet off the ground for nests but only uses them for about a year. After the hole is abandoned other bird species, such as the elf or pygmy owl, will move into the hole. This woodpecker and the saguaro have a mutual relationship. The hole itself does not damage the saguaro very seriously because the bird does not penetrate the internal ribs of the cactus. The woodpecker, in turn, eats saguaro seeds, aiding the cactus in spreading offspring.


Tarantula (Aphonopelma chalcodes)

Range: common to North American deserts with dry, warm climate, specifically the Sonoran, Chihuahuan and Mojave deserts.
Size: 2-3 inches long

The tarantula is a spider whose large, hairy body has aided in the creation of many unfounded myths that they are deadly creatures. The truth is that they are harmless to humans. A bite from this spider, which occurs after extreme provocation, will cause nothing more than slight swelling and itching. Tarantulas, like other spiders, have eight legs, eight eyes, and can produce silk. They do not, however, use this silk to spin a web to catch food. Rather, they are active predators that run after their food; the silk is used for lining their burrows. They feed on small insects and sometimes lizards. In order to capture food, the tarantula, using its speed, bites its prey with small fangs and injects a small amount of venom. It then grinds its prey into a ball, injects digestive fluids, and swallows the now liquefied insides of the prey. It may also wrap the ball into silk and save it for a later meal. In order to protect itself, the tarantula will rub its legs over its body, flinging hairs into its attacker’s face. Tarantulas live in holes dug in the ground and can survive for almost 30 years.


Tarantula hawk (Pepsis formosa)

Range: California and Mexico.
Size: 1–2 inches long

The tarantula hawk is a wasp that can grow up to two inches long. This insect has a metallic blue-black body and bright red-orange wings. It has very few natural enemies because the sting is extremely painful, but will be taken by a roadrunner if it happens to be too heavy to fly after consuming fruit or nectar. The adult tarantula hawk eats nectar while the larvae (young) eat tarantulas. An adult female will find a tarantula, sting and paralyze it, and drag the spider into a burrow. She then lays a single egg on the spider’s abdomen and seals the tarantula in the burrow, where the egg hatches. The small larvae feeds on the spider until it is fully grown. Although the sting of a tarantula hawk is very painful, it is less dangerous than a honey bee sting.


Gila monster (Heloderma suspectum)

Range: Western and southern Arizona to southern Sonora, Mexico, southeast California, southern Nevada and extreme southwest New Mexico and Utah. Size:18-24 inches in length

The Gila monster and its close relative, the Mexican beaded lizard, are the only two venomous lizards in the world. It is a sluggish, nocturnal lizard that feeds on small mammals, birds, and eggs. The Gila monster has black skin with bands of pink, yellow, and orange that not only allows it to blend into its surroundings, but also serves as a warning pattern to a potential predator. Its large body is able to consume food at a fast rate, and once full it can store fat in its tail, allowing it to survive for long periods of time without feeding. Its metabolic rate is also very slow, which helps food last even longer. It kills its prey by clamping down on a bite spot and injecting venom into the wound, refusing to open its jaws. They are named for the Gila River Basin of Arizona.


Banner-tailed kangaroo rat (Dipodomys spectabilis)

Range: from northeastern Arizona to Aguascalientes and San Luis Potosi, Mexico, and from southern Arizona to west Texas.
Size: 9-14 inches, with the tail being longer than the head and body. Weighs 1-6 ounces.

These rodents live in well-developed desert grass- and shrub-lands, where they create intricate burrow systems. Their hind legs and back feet are adapted for quick motion, which is essential in their desert habitat. They are nocturnal creatures whose natural predators include badgers, kit foxes, coyotes, bobcats, owls, and humans . They feed on grasses and seeds that they can store in cheek pouches. In order to survive with small amounts of water, these rats have evolved several adaptations. First, they do not need to drink water because they obtain moisture from seeds and do not pant or sweat. In addition, the air in their burrows contains more moisture than the dry outside air. This moisture is what allows them to survive with little to no water. Finally, kangaroo rats have kidneys that excrete wastes with little loss of water.


Cactus ferruginous pygmy owl (Glaucidium brasilianum cactorum)

Range: Central Arizona to Argentina.
Size: weighs about 2.5 ounces and is 6-7 inches long

This small owl species nests in holes made by Gila woodpeckers in cacti or large trees, which provide cover from its predators. The pygmy owl has a very large home range for such a small bird. It takes between 30 and 125 acres to support enough prey for one bird. It feeds mostly on lizards and insects, but also on birds and small mammals such as mice. Tree-cutting and groundwater pumping in the last century have decreased the amount of suitable habitat for this species. Therefore, populations are in decline, leaving only a few individual owls left in Southern Arizona. There is a bigger population of pygmy owls in Sonora, Mexico that some researchers think may be used to replenish the population in the United Sates.


Sonoran coral snake (Micruroides euryxanthus)

Range: Central Arizona to northern Mexico and the southwest corner of New Mexico.
Size: 13 to 21 inches long

The Sonoran coral snake is a colorful animal with broad, alternating rings of black and red separated by smaller rings of white or yellow. It is a venomous snake, that, when threatened, will first coil itself then bury its head under its body and make a popping sound with its tail. This behavior can both confuse and warn potential predators. This early warning signal also makes it unlikely for a human to be bitten by the snake unless the person is very persistent. The venom is comparable to a cobra’s venom, but the Sonoran coral snake has a smaller mouth and fangs, making it less dangerous. It feeds on blind snakes that are about the size of worms and at times eats small lizards. It is diurnal in the spring, nocturnal in the summer, both in the fall, and rarely comes above ground in the winter.

Sonoran desert toad (Bufo alvarius)

Range: central Arizona, southwestern New Mexico, and Northern Mexico.
Size: 7 inches long or more

This toad is one of the largest native toads in North America. Previously named the Colorado River toad, it has a weak call that can sound like a faint, low-pitched ferry whistle. They release a toxin from their glands that is strong enough to kill household pets. The toxin is an adaptation to fend off predators, such as hawks and snakes, that have to eat the toad slowly. Sonoran desert toads feed on large beetles and have been known to eat small vertebrates as well. During dry periods, this toad buries itself in mud, relying on fat stored in the body, and hibernates until rain comes again. A female toad can lay up to 8,000 eggs in water. Metamorphosis from tadpole to adult takes between 3 and 8 weeks.


Lowland leopard frog (Rana yavapaiensis)

Range: Only found in areas with permanent water in the Sonoran Desert.
Size: Males average 2 inches long; Females average 3-3 1/2 inches long

The lowland leopard frog is an amphibian found in permanent springs, lakes, and ponds of the arid Sonoran Desert. This is a spotted frog with thin, smooth skin that must stay moist. Adults eat insects and need permanent water in order to reproduce. Like many frog species, eggs hatch into tadpoles that feed primarily on algae. Larvae then metamorphose into small frogs that resemble adults. In contrast to other desert amphibians, lowland leopard frogs spend a longer period of time in the tadpole stage. For example, Sonoran desert toad tadpoles develop in 3 to 8 weeks because they are found in temporary pools; lowland leopard frog tadpoles mature in 3 to 9 months because they are found in permanent water. Lowland leopard frogs, along with amphibian populations worldwide, are declining in numbers and are a protected species in the state of Arizona. Invasive species and the degradation of habitat are some reasons for this decline. Non-native fish, bullfrogs, and crayfish impact native frogs by competing for resources, decreasing water quality, and consuming them as food. In addition, human water use has decreased the amount of standing water in many areas of the Sonoran Desert, drying places where frogs were once found.



Desert Views Trail at ORPI

Experience the desert through this virtual reproduction of the Desert View Nature Trail in Organ Pipe Cactus National Monument. You may experience this trail in either Spanish or English.

Welcome to the Sonoran Desert- a land that fed, housed, and shaped the culture of many generations of desert dwellers. Early inhabitants were dependent on this desert, and survival meant using the abundant plant and animal life around them for food and other practical uses. Many of the remedies they discovered and religious practices they developed are continued by their descendents today. So now it is time to explore the many ways the Sonoran Desert nurtures human life.


Sendero Panorámico del Desierto

¡Bienvenidos al Desierto Sonorense!- tierra que ha definido la cultura de numerosas generaciones de habitants desérticos, ofreciéndoles sustento y abrigo. Los primeros moradores dependían de este desierto, donde para sobrevivir era necessario aprovechar la abundancia de plantas y animals del etorno como fuente alimenticia y para otros fines practices. Actualmente, sus descendientes contiúan usando muchos de los remedies que ellos descubrieron y mantienen vivas muchas de sus tradiciones religiosas. Ahora exploramos algunas de las diversas maneras en que el Desierto Sonorense nutre y facilita la existencia del ser humano.

1. The desert cures - Unlocking the secrets of the desert was a slow and laborious process of trial and error for the early inhabitants. Their ability to use the subtle Sonoran Desert plant and animal life proved that the desert could sustain human life. The journey to find and free the healing qualities of the Sonoran Desert continues today as scientists learn the curative properties of some plants and develop new uses for others.

1. Los remedios del desierto - Para los primeros habitants, descubrir los secretos del desierto fue un proceso de experimentación lento y arduo. Al hacer uso de los sutiles animals y plantas del Desierto Sonorense, comprobaron que se podia sobrevivir en el desierto. Los cientificos de hoy en día que se dedican a investigar las propiedades curatives de ciertas plantas y a determinar nuevos usos para otras, continúan por ese mismo camino con el fin de descubrir y aprovechar las cualidades sanadoras del Desierto Sonorense.


2. Creosote Bush (Larrea tridentata) A Universal Remedy - Its leaves were boiled to make tea as a remedy for colds, tuberculosis, venereal disease and intestinal disorders. On the smoke of creosote fires, O’odham soothed their aching feet after long treks through the desert. The women would lie on heated branches to ease the soreness of childbirth.

2. Gobernadora Un remedio universal - Se hervían las hojas de la gobernadora para hacer una infusion que servía como remedio para los resfriados, la tuberculosis, las enfermedades venéreas, y los problemas intestinales. Después de prolongadas caminatas por el desierto, los o’odham se valiant del humo de las fogatas de gobernadora para calmar el dolor de sus pies. Para mitigar la indisposición producida por el parto, las mujeres se tendían sobre las ramas calentadas de este arbusto.


3. Compass Barrel Cactus of Bisnaga (Ferocactus emoryi) The lifesaving cactus - The coville barrel cactus tends to grow faster on the shaded north side, making it point towards the south- hence the name “compass cactus.” Supposedly, this cactus saved many thirsty desert travelers, but the slimy, alkali juice of the inner pulp is unfit to drink.

3. Biznaga o “Cactus Brújula” El cacto salvavidas - La parte de esta biznaga que se encuentra expuesta hacia el norte recibe más sombra y tiende a desarrollarse con mayor rapidez por lo cual la planta entera se inclina hacia el sur, y por esta razón ha llegado a llamarse el “cacto brújula.” Se suponía que la pulpa interior de este cacto había salvado de la deshidratación a muchos viajerso sedientos en el desierto, pero esto es solo un mito. Solamente es possible extraer agua en pequeñas cantidades, y resulta insalubre beberla en abundancia.


4. Cactus skeletons - Life after death - Many desert plants continue to serve uselful purposes even when dead. The woody skeletal ribs of the saguaro and organ pipe were used to construct O’odham shelters and as framework and roofing materials for homes by early settlers. Birds perch on and nest in the skeletons and many other animals find shelter in the decaying wood.

4. Los esqueletos de los cactos - La vida después de la muerte - Aún en la muerte, numerosas plantas desérticas continúan siendo útiles. Loso’odham empleaban los esqueletos leñosos de las costillas del saguaro y de la pitahaya dulce en la construcción de sus refugios, y los primeros colonizadores los usaban como material para los armazones y los techos de sus viviendas. Las pájaros se posan y hacen sus nidos en los esqueletos muchos animals se refugian en su madera podrida.


5. White ratany ( Kramaria grayi) - Tea time - Using the roots of this plant, pioneers made a pleasant-tasting tea, which was considered beneficial for the blood and kidneys. O’odham Indians used a similar decoction for treating coughs. Chewing on a piece of root to soothe sore throats is still a common practice among Sonorans today.

5. Cósahui - La hora del té - Los pioneros usaban las raíces de esta planta para preparar un té de sabor agradable que, según se creía, beneficiaba la sangre y los riñones. Los indigenas o’odham preparaban una decocción semejante para curar la tos. En la actualidad, los sonorenses continúan con la costumbre de masticar trozos de esta raíz para aliviar las inflamaciones de la garganta.


6. Buckhorn cholla (Opuntia acanthocarpa) - For hard times - Early spring was called ko’oak macat (the painful moon) by the Tohono O’odham because of scarce food supplies. During this season, they turned for cacti for food and pit-roasted thousands of calcium-rich cholla flower buds. Today’s O’odham people still pit-roast or boil the cholla buds, which taste like asparagus tips.

6. Cholla - Para los tiempos difíciles - Los tohono o’odham le dieron el nombre de ko’oak macat (luna dolorosa) al principio de la primavera debido a la escasez de alimentos en esa época del año. Durante este período, dependían de los cactos para su nutrición, y asaban millares de capullos de las flores de la cholla que son tan ricas en calico. En la actualidad, los o’odham aún cuecen o asan los capullos de la cholla cuyo sabor asemeja del espárrago.


7. Fishhook pincushion cactus (Mammillaria grahami) The little one - The O’odham rubbed elongated scarlet-colored fruit from this tiny cactus into their arrowheads to give them color. They also sliced and boiled the minute fishhook-shaped spines and placed them warm in the ear to cure earaches.

7. Cabeza de Viejo - Los o’odham acostumbraban restregar la alargada fruta escarlata de este pequeño cacto sobre las puntas de sus flechas para darles color . Para curar el dolor de oído, cortaban en tajadas las diminutas espinas en forma de anzuelo, las cocían y, estando tibias, las introducían por la oreja.


8. Limber bush (Jatropha cuneata) Flexible bushes - In Spanish, the limber bush is called sangre-de-drago (blood of the dragon) because of the red dye found in the sap. The O’odham people made baskets out of limber bushes where the other major fiber grasses, beargrass and yucca, were not available.

8. Sangre-de-drago - Arbustos flexibles - Este arbusto llegó a llamarse sangre-de-drago (sangre de dragón) en español debido al tinte rojo de su savia. Los o’odham usaban la sangre-de-drago en la fabricación de sus canastas cuando no disponían de la palmita y la yuca que son las otras plantas fibrosas de importancia.


9. Ocotillo (Fouqueria splendens) The living fence - O’odham and Sonoran homesteads often used cuttings of ocotillo for fences, which provided protection and privacy. Fences made of cut ocotillo stems sometimes rooted, creating a “living” fence. Sheds, outbuildings and “sandwich houses” were made from ocotillo and mud walls, with mesquite corner posts and saguaro rib crossbars.

9. Ocotillo - La cerca viviente - Los o’odham y los sonorenses frecuentemente circundaban sus viviendas con cercas construidas de ramas de ocotillo, lo cual les daba protección y aseguraba la intimidad de sus hogares. A veces las vallas hechas de ramas de ocotillo echaban raíces, volviéndose entonces cercas “vivientes.” Las casas y las estructuras anexas se construían con paredes dobles de ocotillo rellenas con barro, con postes de mesquite en cada esquina y travensaños hechos de costillas de saguaro.


10. Organ pipe cactus (Stenocereus thurberi) The monument’s namesake - O’odham and Mexican desert dwellers found the fruit of the organ pipe, pitahaya, had many uses. When ripe, it was eaten raw or made into syrup, jams and a mild wine. The seeds were ground to make flour or cooking oil. The fruit was also dried and stored for eating later in the year.

10. Pitahaya dulce - La tocaya del parque - Los mexicanos y los o’odham que habitaban el desierto descubrieron que la fruta de la pitahaya tenía numerosos usos. La fruta madura se empleaban en la preparación de almibar, mermeladas y un vino suave, o simplemente se comía cruda. Las semillas se molían para producir harina o accite de cocinar. La fruta también se secaba y se almacenaba para ser consumida durante el transcurso del año.


11. Prickly pear cactus (Opuntia phaeacantha) A fruit, not a fish - O’odham Indians and locals make preserves and jellies from las tunas, or the fruit of this cactus. From the young pads, they make nopalitos, which taste like green beans. Pads were also heated and applied to body joints to reduce swelling from arthritis and rheumatism.

11. Nopal - Una fruta, no un pez - Los indígenas o’odham y otros habitants de la region preparan conservas y mermeladas de las tunas que son la fruta de este cacto. Usando las pencas más tiernas, preparan los nopalitos cuyo sabor se asemeja a del ejote verde. Las pencas también se calentaban y se ponían sobre las articulaciones del cuerpo para reducir la inflamación causadapor la artritis y el reurnatismo.


12. Mexican jumping bean (Sebastiana biloculare) Not good eating - This species has a white sap used by early desert peoples as poison on their arrows to stun fish, hence the Spanish name yerba de flecha meaning “herb of the arrow.” An O’odham legend says that sleeping underneath this bush causes blindness. Sap or smoke from this burning wood will greatly irritate your eyes.

12. Yerba de flecha (Frijol brineador mexicano) Esto no se debe de comer - Los antiguos pueblos desérticos utilizaban la savia blanca de esta especie como veneno para aturdir a los peces, y de este hecho se deriva su nombre en español “yerba de flecha.” Una leyenda de los o’odham cuenta que el que se duerme debajo de esta mata habrá de quedarse ciego. Tanto la savia como el humo producido por la quema de esta Madera puede causar una grave irritación de los ojos.


13. Brittlebush (Encelia farinose) A holy bush - The brittlebush contains a resin that Mexicans applied as plaster to relieve chest pains. The resin was also used to fix an arrowhead to the shaft and as a glue to mend broken pottery. Franciscan and Jesuit priests used the stems of this fragrant bush as incense in early mission churches. Its Spanish name is incienso.

13. Incienso - Un arbusto sagrado - El incienso contiene una resina que los mexicanos usaban en emplastos para aliviar los dolores del pecho. Esta resina se empleaba también para adherir las puntas de las flechas a sus varas y para reparar artículos de cerámica. En las antiguas misiones, los padres franciscanos y jesuitas utilizaban los tallos de este fragante arbusto como incienso.


14. Desert mistletoe (Phoradendron californicum) Rituals - The O’odham people gathered ripe berries of this parasitic plant and stored them for winter eating. The shaman used this mistletoe in curative rituals and as medicine for stomach ailments. The flowers of desert mistletoe have a lovely fragrance in the late winter.

14. Toji - Ritos - Los o’odham recogían y almacenaban las bayas (fruta pequeña) de esta planta parasitica que les servían de alimento durante el invierno. El chamán usaba el toji en sus ritos curatives y como medicina para las enfermedades del estómago. Las flores del toji producen una fragancia muy agradable a fines del invierno.


15. Ironwood (Olneya tesota) The heavyweight - In late summer, O’odham Indians parched the ripe beans, ate them whole or ground them into a coarse meal called pinole. The dense wood was an excellent material for arrowheads and tool handles. The Seri Indians of Sonora once carved animal figurines from this hard wood. The recent decline in large ironwood trees has prompted them to no longer use this rare and precious wood.

15. Palo fierro - Una madera densa - A fines del verano los indigenas o’odham secaban las semillas de este árbol y las comían enteras o las molían para producir una harina basta llamada pinole. Esta madera, por ser tan densa, representaba un material excelente para fabricación de puntas de flecha y mangos de herramientas. En tiempos pasados, los indios seri de Sonora tallaban figures de animals de esta madera dura. Debido a la reciente disminución del número de palos fiero maduros, han dejado de usar esta madera tan escasa y valiosa.


16. Saguaro (Carnegiea gigantean) A giant among cacti - This cactus is an important source of food and shelter for the Tohono O’odham. They celebrate the beginning of their summer growing season with a ceremony to summon vital rains using a fermented drink made from the bright red fruit of the saguaro. Saguaro spines are sometimes used as sewing needles and the ribs are used to make harvesting tools.

16. Saguaro - Un cacto gigante - Este cacto representa para los tohono o’odham una importante fuente de alimento y de protección en contra de la intemperie. Los tohono o’odham celebran el comienzo de la época del cultivo veraniego con una ceremonia para atraer las lluvias, tan necesarias para las cosechas, en la cual se ingiere una bebida fermentada hecha de la fruta roja de este cacto. Las espinas del saguaro se han utilizado como agujas para coser, y las costillas se emplean como implementos para recoger la cosecha.






Sonoran Desert (current location)

People and Places




The Sonoran Desert Index (multimedia version)

Views of the National Parks Visitor Center