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Sonoran Desert

Last updated over 1 year ago
16 questions
Welcome to the Sonoran Desert! Complete the tasks as you learn all about this unique ecosystem in the southwestern United States.

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The Sonoran Desert

The saguaro cactus is one of the many plants native to the Sonoran Desert.
  • The Sonoran Desert's climate is subtropical, and the area gets about 3 to 15 inches of rain each year, more than any other desert in the world.
  • Broad valleys bordered by mountain ranges from northern Mexico across Arizona, California, Utah, and Nevada, to Idaho's southern plains comprise the Sonoran Desert.
  • The hottest and most bio-diverse desert in North America, the Sonoran is home to at least 30 different animals and 10 different plant species.
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What continent is the Sonoran Desert in?

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What country is the Sonoran Desert in?

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What state(s) is the Sonoran Desert in?

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What type of climate does the Sonoran Desert have?

Sonoran Desert - Abiotic Components

World Atlas (link)
Soil Characteristics (link)
Sonoran Desert (link)

Overview
First-time visitors to Sonoran Desert Network parks are often surprised by the tremendous natural variation between, as well as within, each park. However, the very diversity of species, lifeforms, and landscapes is one of the common threads that unifies SODN parks.
The Sonoran Desert is thought to have the greatest species diversity of any desert in North America, and that diversity occurs over relatively fine spatial scales. The Sonoran Desert is home to at least 60 species of mammals, more than 350 bird species, 20 amphibians, some 100 reptiles, and about 30 species of native fish. More than 2,000 species of plants have been identified in the Sonoran Desert, and each of the three physiological groupings of vascular plants (C3, C4, and CAM photosynthetic pathways) dominate one or more major biotic communities.

More striking than species diversity is the tremendous variability in Sonoran Desert lifeforms, from columnar cacti to conifers, Gila monsters to pygmy owls, cyanobacterial soil crusts to native ferns. Landscape diversity in the Sonoran Desert rivals that of any other terrestrial ecoregion on Earth, with nearly all of the planet's biomes represented, ranging from cold conifer forests to hot deserts, where frost is nearly absent and precipitation rare. This tremendous species, lifeform, and landscape biodiversity is the result of a host of factors: the subtropical climate, continental physiography, bimodal precipitation, varied geology, and wide-ranging topography.


Continental Physiography


The Sonoran Desert occupies approximately 260,000 square km (100,387 square mi) of the southwestern United States and northwestern Mexico, including the southern half of Arizona, southeastern California, and most of the states of Sonora and Baja California, Mexico. Bounded on the north by the Mogollon Rim, the Sonoran Desert grades into the Chihuahuan Desert to the east, the Mohave Desert to the west, and the tropical forests and montane forests of central Mexico to the south. Extending between 23°N and 30°N, the subtropical Sonoran Desert represents a continental-scale ecotone between the tropics and temperate zones of western North America. At a regional scale, the Sonoran Desert serves as a transition between the Sierra Madre and the Rocky Mountains, the Pacific and Gulf coasts, and the coastal lowlands of Baja and the mid-continent.



Geology and Topography
The Sonoran Desert is composed of sedimentary, igneous, and metamorphic rocks with widely varying ages, from 2 billion year-old Precambrian outcroppings in Arizona to relatively recent (ca. 700 A.D.) volcanism in the Pinacate region near the international border. Between 20 and 40 million years ago, numerous volcanoes were active in the Sonoran Desert, resulting in large calderas (basins formed by volcanic explosions), lava vents, and cinder cones. This tectonic activity, coupled with intense heat from below, placed tremendous stress on the crusts underlying the Sonoran Desert, causing the horizontal and vertical movements that produced its characteristic Basin and Range topography.

The result was roughly parallel mountain ranges, many approaching elevations of 3,048 m (10,000 ft), separated by broad valleys flanked by "bajadas" of coalesced alluvial fans. This precipitous topographic relief provides for radical differences in climate along slopes, with the relatively cool and moist (due to orographic precipitation) summits containing lifezones more characteristic of Canada than those of the valley bottoms below. These montane habitats (accentuated by north and east aspects and local topography) are termed "sky islands," which are analogous to actual marine islands from the perspective of biogeography, speciation, and landscape connectivity. In combination with the bimodal precipitation regime and mid-continental position, this tremendous variation in topography over relatively fine scales produces the amazing diversity of the Sonoran Desert.


Climate


Perhaps no feature defines the Sonoran Desert more than its bimodal precipitation regime. Interspersed between the Mohave and Chihuahuan deserts, the Sonoran Desert receives the frequent low-intensity winter (December/January) rains of the former, as well as the violent summer (July/August) "monsoon" thunderstorms of the latter. These distinct rainy seasons support a broad array of warm- and cool-season flora and fauna, and are the primary cause of the amazing species and lifeform diversity of the Sonoran Desert. Winter precipitation occurs when a low-pressure trough develops over the western United States, pushing the prevailing Pacific storm tracks south over the Sonoran Desert. Annual precipitation in the Sonoran Desert averages from 76 to 500 mm (3–20 in) depending on location, with substantial inter- and intra-annual variability in timing and quantity. Precipitation is typically much higher with elevation due to the orographic effects of the sky islands, with a sizable proportion occurring as snowfall. The Sonoran is a hot desert. Summer air temperatures routinely exceed 40°C (104°F), and often reach 48°C (118°F). These high near-surface temperatures interact with cool, moist air in the atmosphere to produce the violent thunderstorms of the summer monsoons. As moisture on the soil surface and near-surface air evaporate following a storm, temperatures may drop 10°C (18°F) or more, often within a matter of minutes. Winter temperatures are mild, with valley bottoms typically free of frost, while the surrounding mountains may have dense snow cover at high elevations and north and east aspects. During any season, diurnal swings of 15°C (27°F) or more are common, as the dry atmosphere and relatively low vegetation cover facilitate re-radiation of daytime heat into the atmosphere overnight.
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How much precipitation does the Sonoran Desert get annually?

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How hot does the temperature get?

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What is the soil composition?

Sonoran Desert - Biotic Components


Desert Flora (plants)

Desert Fauna (animals)

Use the links above to answers the questions.
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List 10 examples of Flora (plant) life.

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List 10 examples of Fauna (animal) life.

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What type of organism is the Saguaro Cactus?

Sonoran Desert - Prickly Pear


Identifying Features
The Engelmann prickly pear cactus (Opuntia engelmannii) can be easily identified by it's broad, flat, green pads. The white spines are 3" long and can be flat, curved or straight. They also are covered with tiny, barbed hairs known as glochids. Groups of up to 6 spines emerge from a common center areas known as areole's which are scattered around each pad. The flowers are yellow and emerge in May-June. Ripe fruit are found beginning in July and are identified by their bright red color.

Habitat
Prickly pear are found growing in washes, rocky hillsides, around boulders, and in areas where the soil is sandy or gravelly.

Range
The Englemann variety of prickly pear can be found over much of the desert southwest from central Texas through inland southern California. Their range extends into northern Baja California and into central Sonora, Mexico.

Life Span
They are known to live well over 20 years.

Size
There are several different varieties of prickly pear cactus each growing to different sizes. The most common species in the Sonoran Desert is the Engelmann prickly pear which grows up to 5 feet tall and can grow to a width of 10-15 feet.

Quick Facts
  • The red fruit or pear of this cactus are also known as "tuna".
  • Prickly pear are the state cactus of Texas.
  • Packrats often build dens at the base of these plant, which then provides protection from some of its predators.
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Describe the Prickly Pear's appearance.

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What is the best soil for growth for the Prickly Pear?

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How big does the Prickly Pear get?

Sonoran Desert - Black-Tailed Jackrabbit


Identifying Features

The black-tailed jackrabbits (Lepus californicus) most identifying feature is its huge ears. The ears along with the tail are tipped with black fur. It has long slender front legs and large hind feet that can be 5 inches in length.

Adaptations

The large ears of this hare help it to lose heat and thereby cooling its body temperature. They have large eyes that are high on their head and placed toward the side. This along with the fact that their head is slightly flat allows them to see almost 360 degrees (a full circle) helping to spot predators.

Habitat

They like open flat places along with desert scrub and mesquite grasslands.

Range

They are found from Baja California and south-central Mexico to west-central and western United States.

Wild Status

Jackrabbits are not threatened or endangered.

Diet

These hares are herbivores, feeding on grasses, leaves, clover, alfalfa, twigs, seeds, beans, twigs and cacti.

Predators

Jackrabbits are an important food source for many animals. These can include coyotes, Red-tailed Hawks, Ferruginous Hawks, eagles, foxes, bobcats, and humans.

Home

Jackrabbits will often rest in the shade during the heat of the day in a shallow depression under grass or bushes. They do not live in burrows. They will often forage or rest in groups relying on the eyes and ears of each other for protection. Females will give birth in thick brush or in depressions lined with fur.

Life Span

In the wild on average jackrabbits live 2-5 years. They usually live longer when in a zoological setting.

Size

Adult black-tailed jackrabbits weigh from 3-7 pounds and are about two feet in length.

Extra Fun-facts

  • The black-tailed jackrabbit is not really a rabbit, it is a hare. This is because its young are born with fur and with their eyes already open.
  • Jackrabbits can run as fast as 40 mph in short bursts in order to escape predators.
  • Baby jackrabbits are called leverets.
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Describe the diet (food) of the Black-Tailed Jackrabbit.

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What predators does the Black-tailed jackrabbit have?

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What kind of shelter does the Black-tailed Jackrabbit have?