||USA & Mexico
||311,000 sq. km (120,000 sq. miles)
The Desert Environment
The Sonoran Desert is one of the largest and hottest deserts in North America and it covers an area of 311,000 sq. kms (120,000 sq. miles). It is situated in south western USA in the states of Arizona and California, and in Mexico in the states of Sonora, Sinaloa and Baja California.
The landscape of the Sonoran Desert is varied; broad, sandy or rocky plains are broken up by numerous barren mountains. There are two major rivers which cross the desert, the Colorado River and its tributary the Gila River and during storms small desert streams are formed but these quickly dry out.
The sub-regions of the Sonoran Desert include:
Gran Desierto de Altar
The Sonoran Desert is one of the hottest in North America. In summer the air temperatures routinely exceed 40°C (104°F) and often reach 48°C (118°F). These high temperatures interact with cool moist air in the atmosphere and they produce the violent thunderstorms of the summer monsoons.
Winter temperatures are generally mild. Valley bottoms are usually free from frost, but the surrounding mountains may have dense snow cover at high elevations and north and east aspects. During December and January there is frequent, low intensity rainfall.
Annual precipitation in the Sonoran Desert averages from 76 - 500 mm (3 - 20 inches) depending on location.
The Sonoran Desert is abundant in shrubs and trees that have adapted to survive in hot, arid conditions. Their probing roots take as much moisture as possible from the soil, and they generally have small, waxy leaves that minimize water loss.
Cacti are among the most striking desert plants. They have spines that are actually modified leaves and after a rainstorm their roots absorb water very quickly and it is stored for long periods within their stems. The Sonoran Desert is the only place in the world where the famous Saguaro Cactus grows in the wild. Other species of cacti include cholla, bevertail, hedgehog, fishhook, prickly pear, night blooming cereus and organ pipe.
Creosote bush, bur sage, indigo bush, and mormon tea are examples of shrubs that may be found and wildflowers of the Sonoran Desert include desert sand verbena, desert sunflower, evening primroses, desert marigold and bluebonnet.
Much of the wildlife of the Sonoran Desert has adapted to cope with the harsh heat and periods of drought. Some species shelter underground during the day and emerge at night to feed, while others remain underground for months and emerge after seasonal rainfall has improved their food supply.
Invertebrates - the Sonoran Desert is home to a vast number of species of invertebrate which include spiders, scorpions, beetles, mites, wasps and bees.
Reptiles - the most impressive reptile that can be found in the Sonoran desert is the venomous Gila Monster, although they are generally shy and retiring creatures. Other reptiles include the desert iguana, collard lizard, zebra-tailed lizard, sonoran sidewinder, western diamondback rattlesnake, sonoran mountain kingsnake and the black mexican kingsnake.
Birds - one of the most remarkable birds that can be found in the desert is the greater roadrunner. They dart across the ground at up to 25 km/hr and they capture a variety of prey including venomous rattlesnakes. The gila woodpecker and gilded flicker often drill their nest holes in the giant saguaro cactus and these are sometimes taken over later by elf owls. Other species of bird include anna's hummingbird, costa's hummingbird, canyon wren, lawrence's goldfinch, spotted owl, lucy's warbler, cactus wren, mourning dove, sage sparrow, bendire's thrasher and grey vireo.
Mammals - Over 60 species of mammals can be found in the Sonoran Desert and these include predators such as the kit fox and the coyote. Other species of mammals include the antelope squirrel, desert pocket mouse, desert kangaroo rat, round-tailed ground squirrel, ringtail, lesser long-nosed bat, desert bighorn sheep, and the black-tailed jackrabbit.
Amphibians - there are around 20 species of amphibians found in the Sonoran Desert which include the colorado river toad.
The Sonoran Desert is home to over 17 contemporary Native American tribes. They have settlements at American Indian Reservations in California and Arizona as well as populations in Mexico.
The largest city in the Sonoran Desert is Phoenix, Arizona which has a population of approximately 4.3 million people.
There are many parks, conservation areas, research facilities etc in the Sonoran Desert and these include:
Arizona - Sonora Desert Museum
Saguaro National Park
Joshua Tree National Park
South Mountain Park
Kofa National Wildlife Refuge
Coachella Valley National Wildlife Refuge
Organ Pipe Cactus National Monument
Sonoran Desert National Monument
Indio Hills Palms State Reserve
Sonoran Arthropod Studies Institute