Plants

There are somewhere between five and six thousand desert plants (Jaeger 1957).  The desert plants that are primarily responsible for brilliant displays of color are the late winter, spring, and summer annuals; although flowers are always in bloom somewhere in the desert.  These annual plants are able to survive the harsh heat and dryness of the deserts by going dormant in the form of seeds, therefore allowing them to escape drought altogether.  After a rainfall, the seeds germinate and grow rapidly, often forming beautiful desert blooms which carpet the desert with flowers (Raven and Johnson 1992).

Perennial flowering herbs, shrubs, and deep-rooted trees, such as sagebrush, boojums (picture on the right) and cacti, comprise much of the southwestern desert landscape.  These plants withstand seasons and sometimes years of little rainfall with adaptations such as inflated stems for water storage, deep root systems and wax coated leaves or leaves of small size which cut down on evaporation possibilities (Walter and Stadelmann in Brown 1974).  Sagebrush covers thousands of square miles in the Great Basin Desert while cacti are more common in the more southern deserts.  Grasses also account for up to several hundred species of perennials, making up a large portion of the perennial species growing in the deserts (Costello 1972).
 

Invertebrates

Desert invertebrates are successful inhabitants of the deserts.  Their thick exoskeletons prevent water loss through evaporation allowing them to survive the hot and dry desert environments.  Despite their small size, insects are dominant animals in the desert world (Costello 1972).  They are an important part of the food chain as so many other organisms are directly dependent on their existence.  Insects are most important to other arthropods such as spiders, ticks, scorpions, centipedes and millipedes that prey upon these insects for their survival  (Edney in Brown 1974 and Leopold 1962).  Arthropods are capable of eating their own weight in insects daily, which is a useful function, serving to control the explosive reproduction of insects in the deserts (Leopold 1962).   Insects such as crickets, locusts, wasps, butterflies, grasshoppers and caterpillars are also important food sources for birds, bats, reptiles and other organisms.
 

Birds

Birds are highly visible in the desert because of sparse foliage cover.  They use shrubs, cacti, and low trees for perching places.  Desert birds sing from the highest vantage points in the landscape - the desert plants. Thus, in establishing their territories they can be seen as well as heard by other birds.  The less vociferous birds commonly inhabit the desert trees, especially along dry washes and riverbanks (Costello 1972).  Soaring eagles, hawks, and buzzards are often easy to pick out in the sky (Jaeger 1957).
 

Hundreds of species of birds frequent the desert.  The desert's resident birds are largely insect - and spider eaters, birds of prey, or scavengers (Jaeger 1957). Desert birds include cardinals, road runners (picture on the right), towhees, long spurs, kingbirds, tanagers, quails, owls, nighthawks, swifts, crows, woodpeckers, grouse, wrens (picture above), thrashers, and sparrows (Costello 1972 and Leopold 1962).  Some of the birds, such as the magpies, are year long residents; others like the hummingbirds, the American golden plovers, some of the gulls, and many others are migratory birds or are transients found in the desert only in spring, fall or winter (Costello 1972).  Using the desert only for a breeding ground allows birds to avoid seasons of extreme heat, cold and drought (Leopold 1962).

 
Fishes

There are approximately 20 species of true desert fish in the western U. S. and northern Mexico (Leopold 1962). These animals are particularly fragile because they are confined to few permanent water areas such as springs, water holes and streams (Deacon and Minckley in Brown 1974).  This creates a lack of species diversity allowing the impacts of introduced species, cattle and agricultural runoff to be exaggerated (Fitch and Adams 1998, Leopold 1972, Cole in Brown 1968).   Several species of fish have become extinct in recent years due to such impacts (Deacon and Minckley in Brown 1974, Leopold 1972).
 

Amphibians

Frogs and toads are the primary amphibians found in deserts (Bodenheimer 1935 in Brown 1968). These animals and some salamanders can collect in extremely small amounts of water in the desert (Leopold 1962); however, they are very abundant for only short periods of time during rainfall.  During rainless periods amphibians go into aestivation (hibernation) (Costello 1972).  The spade foot toad, for example, has a sharp projection on the pack of each hind foot that he uses for burrowing into the ground when drought sets in so he can begin aestivation underground when dry conditions persist (Leopold 1962).  Other organisms such as the desert toad, the woodhouse toad, the Pacific tree toad, the California tree frog, the desert slender salamander, and tiger salamander are other amphibian representatives as well (Costello 1972).

 
Reptiles

Reptiles are probably the most conspicuous and common animals of the desert although the desert wilderness is not frequented by these animals as much as some may imagine (Jaegar 1957).  The scaled or plated skin of reptiles makes them highly resistant to drying, an essential adaptation to the hot, dry desert environment.  An example of this is the desert tortoise (picture at left).  Desert reptiles also protect eggs from the the harsh environment by placing them deep in the soil where the moisture is prime for hatching (Leopold 1962).  Most lizards are insect eaters, however there are a few vegetarian exceptions like the chuchwalla (Leopold 1962).  Lizards such as the spiny lizard, the prickly horned lizard, or the Gila monster can be spotted frequently during the day while snakes are more frequently seen at night (Leopold 1962).  In numbers and in species, snakes are less common than lizards probably due to a diet that is less abundant than the insect diet of lizards.  A few snakes of the deserts are insectivorous, but most feed upon other vertebrates such as frogs, lizards, and rodents (Leopold 1962).
 

Mammals

Rodents such as ground squirrels, pocket gophers, wild mice, pack rats (see picture at right) and kangaroo rats represent the greatest portion of mammals in the desert. As many as nine kinds of rodents may live comfortably on one acre of desert land (Costello 1972). The success of these small rodents lies in their unique specialization's that allow them to thrive a wide variety of niches.

Coyotes, foxes, bobcats, and skunks are the principle carnivores of the deserts. They drink at water holes when possible, but depend primarily on the blood of insects, birds, reptiles, and mammals, which are their chief food sources for liquid uptake (Jaeger 1957).