Chapter 5 - Deserts

The Sahara Desert

Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than >250 mm/year (10 inches/yr). Although most deserts, such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter. Disturbances are common in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding.

There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat. Deserts often provide little shelter from the sun for large animals. The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles. Mammals are usually small, like the kangaroo mice of North American deserts.

Opuntia sp. (indicator plant of deserts)

Desert biomes can be classified according to several characteristics.
There are 3 major types of deserts:

• Tropical
• Temperate (cold)
• Coastal
  

The tropical desert is an environment of extremes: it is the driest and hottest place on earth. Rainfall is sporadic and in some years no measurable precipitation falls at all. Tropical deserts are found in Baja California and interior Mexico in North America.
The animals include small nocturnal (active at night) carnivores. The dominant animals are burrowers and kangaroo rats. There are also insects, arachnids, reptiles and birds. The animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler.

These deserts are characterized by cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summer. They occur in the Antarctic, Greenland and the Nearctic realm. They have short, moist, and moderately warm summers with fairly long, cold winters. The mean winter temperature is between -2 to 4° C and the mean summer temperature is between 21-26° C. Examples of temperate deserts would be the Gobi Desert of Mongolia (the Himalayas) and the Great Basin of the southwestern US (The Sierra Nevada).

Coastal deserts generally are found on the western edges of continents. They are affected by cold ocean currents that parallel the coast. Because local wind systems dominate the trade winds, these deserts are less stable than other deserts. Winter fogs, produced by upwelling cold currents, frequently blanket coastal deserts and block solar radiation. Coastal deserts are relatively complex because they are at the juncture of terrestrial, oceanic, and atmospheric systems. A coastal desert, the Atacama of South America, is the Earth's driest desert. In the Atacama, measurable rainfall--1 millimeter or more of rain--may occur as infrequently as once every 5-20 years. Example is the desert in Namib, Africa.

Morning fog moistens the dunes of the Namib coastal desert

The largest animal of the desert is the camel. Camels have the ability to store large amounts of water for a long time enabling it to survive in the harsh, dry desert. Camels are the main transportation of the desert dwellers. They have a transparent eyelid that keeps sand out of their eyes.

Ant Ants are social insects found worldwide in almost every environment.

Antelope Antelopes are graceful mammals with beautiful horns.

Arabian Camel The Arabian Camel is the one-humped camel (it is also known as the dromedary).

Arabian Horse Arabian Horses are a distinctive and elegant breed of riding horses that were bred by Bedouins thousands of years ago.

Armadillo The armadillo is a small, burrowing, armored mammal.

Bactrian Camel Bactrian Camels are two-humped camels from deserts and steppes of Asia.

Bandicoot Bandicoots are marsupials with pointy snouts.

Bat Bats are the only flying mammal.

Bighorn Sheep The bighorn sheep is a wild brown sheep from mountains and deserts of North America.

Bilby The bilby (also known as the rabbit-eared bandicoot) is a small marsupial with long ears.

Black Widow Spider A very poisonous spider with a distinctive red hourglass marking.

Blue-tongued Skink An Australian lizard with a long, blue tongue.

Boa Constrictor A large constricting snake from South and Central America.

Bobcat A fierce, short-tailed wild cat from North America.

California Quail The California Quail (also known as the Valley Quail) is a plump bird with a forward-facing head plume.

Camel Camels are large mammals that live in dry areas.

Collared Peccary A pig-like mammal, also known as the javelina, from deserts and chaparrals of North and Central America.

Coyote Coyotes are meat-eaters related to wolves.

Deer The deer is a shy, fast-moving plant-eater.

Desert Tortoise A tortoise from southwestern North America.

Dingo The dingo is a wild dog from Australia.

Donkey Donkeys are hoofed mammals adapted to desert life.

Dragonfly The dragonfly is a flying insect with a long abdomen.

Dromedary The dromedary is the one-humped camel (also known as the Arabian Camel).

Eagle The eagle is a large bird of prey.

Fennec Fox The Fennec fox is a small, desert fox with very large ears; it lives in the Sahara and in northern Saudi Arabia.

Flamingo The flamingo is a long-legged bird that eats crustaceans. Flamingos live in a variety of habitats, including warm coastal areas, high, snowy mountains, and near alkali lakes in deserts.

Fox The fox is a meat-eating mammal with a long, bushy tail.

Gazelle Gazelles live in herds in Africa.

Gecko Geckos are the only lizards that make noise. Many geckos live in desert.

Gerbil The gerbil is a small, long-tailed rodent that is native to dry, sandy areas of Africa and Asia.

Gila Monster A venomous lizard from deserts of southwestern North America.

Goat Goats are sure-footed, hoofed mammals.

Gray Wolf Gray wolves are carnivores that live in packs and howl.

Great Horned Owl A large bird of prey from North and South America.

Hedgehog Hedgehogs are small mammals that can roll into a prickly ball.

Iguana Iguanas are plant-eating lizards.

Jack Rabbit Jack rabbits are hares; they have very long legs and long ears.

Javelina A pig-like mammal, also known as the collared peccary, from deserts and chaparrals of North and Central America.

Jerboa The jerboa is a small, long-tailed rodent that hops.

Kangaroo Kangaroos hop and have pouches. Their babies are called joeys.

Kangaroo Rat A small rodent from North America.

Llama Llama are woolly mammals from South America.

Mongoose Mongooses are sleek, meat-eating mammals.

Mouse Mice are small rodents with long, scaly tails.

Nabarlek A small wallaby from northern Australia.

North American Porcupine The North American Porcupine is a mammals that has protective, needle-like quills on its body.

Oryx Oryx are long-horned antelopes from dry areas in Africa.

Ostrich The ostrich is the largest bird. It can't fly, but it runs very fast.

Owl Owls are nocturnal hunters with eyes that face forwards.

Peregrine Falcon The fastest flyers, who prey upon other birds.

Pika Pikas are small, furry mammals who stockpile food for winter.

Porcupine Porcupines are mammals with protective, needle-like quills on their body.

Pronghorn Pronghorns are the fastest moving mammals in North America. The Sonoran Pronghorn lives in semi-desert areas.

Puma A long-tailed wild cat with no spots. It is also known as the catamount, panther, mountain lion, and cougar.

Pupfish A small fish from desert waters of southwestern North America.

Quokka The Quokka is a marsupial from Australia, a type of wallaby.

Rabbit A fast-moving mammal with long ears.

Rabbit-eared Bandicoot Also known as the bilby, this small Australian marsupial has long ears.

Rattlesnake Rattlesnakes are venomous snakes that have a rattle at the end of the tail.

Red Fox The Red Fox is a meat-eating mammal with a long, bushy tail.

Red Kangaroo Red Kangaroos are large roos from Australia.

Red-Tailed Hawk The Red-Tailed Hawk is a bird of prey, a raptor from North America.

Roadrunner Also known as the Ground Cuckoo, this bird is a fast runner that rarely flies.

Scorpion A venomous arachnid with a large stinger on its tail. Found worldwide except in Antarctica.

Serval A long-legged African wild cat.

Sheep Sheep are mammals with thick, furry fur and hoofed feet.

Shrew Shrews are tiny mammals that are quite ferocious.

Snow Leopard Snow Leopards are rare, pale leopards from the snowy central mountains of Asia.

Spider Spiders have eight legs.

Suricate Suricates (also known as meerkats) are a type of mongoose that can stand upright.

Tarantula A tarantula is a large, hairy spider.

Valley Quail The Valley Quail (also known as the California Quail) is a plump bird with a forward-facing head plume.

Vampire Bat Vampire bats are the only bats that drink blood.

Veiled Chameleon A chameleon with a helmet-like casque on its head.