Some Quick Facts About the Sonoran Desert:
1. The Sonoran Desert is a big place - over 100,000 square miles! Much of the Sonoran Desert lies in Mexico, partly in the state of Sonora, where the desert gets its name. The rest of the Sonoran desert lies in the states of Baja California Norte and Baja California Sur in Mexico and Arizona and California in the U.S.
2. The Sonoran Desert is the hottest and most biodiverse of the North American deserts.
3. The Sonoran Desert is home to 60 species of mammals, more than 350 kinds of birds, 20 amphibians, around 100 reptiles and over 2000 native species of plants. What makes the Sonoran Desert such an abundant place? The Sonoran Desert has so much plant and wildlife and a great amount of biodiversity because of two rainy seasons. Winter storms from the Pacific nourish annuals such as poppies and lupine. Summer monsoons originating from the Gulf of Mexico help both annuals and woody plants. In addition to having two rainy seasons, the desert is bordered by mountains, which receive much greater rainfall and snowfall. Water accumulated by the mountains drains into rivers that cross the desert, creating corridors of riparian vegetation even during dry times of the year.
4. The Sonoran Desert is so dry because high temperatures evaporate the little rainfall it gets. The Sonoran Desert gets such little rainfall for several reasons:
Its 30º latitude - a horse latitude. A horse latitude is created because warm, wet air near the equator rises, cools, and drops its moisture in heavy rains (creating tropical rainforest areas near the equator). By the time the air reaches the high altitudes, it is cold and dry and can not rise further, so it spreads out and moves toward the poles and near the 30º north and 30º south, it begins to sink toward the earth's surface., preventing moisture from reaching the area from elsewhere. Many of the worlds deserts are found at these latitudes.
A double rain shadow. Wet air moving up windward mountain slopes expands and cools, clouds form, and the moisture falls out as rain or snow. By the time the air descends the leeward slopes (contracting and reheating as it goes) it has been drained of moisture. As a result, lands down-wind of mountain ranges tend to be dry.
5. Sonoran plants and animals have developed unique ways to survive.
The roots of the Mesquite tree can bore down 30 meters into the soil to find moisture.
Some plants die completely above ground, but survive underneath the soil as thickened roots, bulbs, tubers, rhizomes and nodules of a variety of designs, structures and sizes.
Some trees, like the ironwood and ocotillo, lose their leaves during times of drought, much like trees in Michigan during the winter.
Kangaroo rats, one of the smallest desert mammals, can survive their entire lives without drinking a drop of water. They get their water from dry seeds and the occasional leaf or insect. The kangaroo rat has a highly effective metabolic system to conserve and recycle any water it does consume. For example, the kangaroo rat pees a highly concentrated paste. Nasal passages are also designed to cool the rat's breath so it condenses the moisture into little water droplets that are reabsorbed into the rat's body.
Roadrunners spend most of their lives on the ground and can run at speeds up to 40km/hr. Running is actually less strenuous and requires less energy than flying, allowing the roadrunner to conserve water and energy.
Spadefoot toads estivate (a hibernation type state) for 8-9 months of the year. A horny projection on each hind foot acts as a digging tool to make a burrow underground. Then the toad secretes and covers itself with a slimy substance to keep it from drying out during its very long nap.