Mammals have special problems adapting to life in the desert. They have to keep their body temperature constant, they lose water quickly and must have adequate supplies of moisture, and they also need plentiful supplies of food. It is therefore surprising that the deserts of the world are home to many groups of mammals including large animals like gazelle, camels, goats and giraffe as well as smaller species like ground squirrels, foxes, meerkat and rabbits. (For more details of African mammals see ╘Mammals of Africa╒, ZooGuides volume 3).
This chapter does not detail every kind of mammal found in desert environments, but it does give a representative cross section of desert species.
Antelope
Antelope are related to goats, sheep and cattle. These animals are all members of the family Bovidae: they are all ruminants and are also characterised by hollow horns and the presence of hooves. Ruminant animals ╘chew the cud╒ by regurgitating food from their stomachs so that they can break down the tough fibers in grasses and other plant material.
Antelope live in Africa and parts of Asia. The desert species include the oryx , found in the deserts of Africa and Arabia. The shorter-horned species (common oryx ╨ Oryx leucoryx or Oryx gazella) is found in Africa, and the Arabian scimitar-horned oryx Oryx tao used to be found on the semi-desert edges of the Sahara as well as on the Arabian peninsula. The scimitar-horned oryx almost died out in the 1960s and the way in which they have been saved is discussed in the ╘Living Desert╒ chapter of this ZooGuide (see the section ╘Conservation╒). Other endangered desert antelope include the addax Addax nasomasculatus. Once distributed throughout the Sahara, there are now thought to be only a few dozen left in Algeria, Niger and the Sudan.
Desert antelope are adapted to survive on tough, dry grasses, supplemented with foliage. The common oryx can endure heat and dessication by allowing its body temperature to rise as high as 113íF, and it can obtain moisture from water-storing roots and tubers when water is unavailable.
Bats
Bats are nocturnal mammals (order Chiroptera) which often live in desert areas when appropriate daytime sleeping places are available, for example caves, abandoned mines or buildings. Both fruit and insectivorous bats are found in the American southwestern deserts. The California leaf-nosed bat Macrotus californicus and the long-tongued bat Choeronycteris mexicana are both desert-dwelling fruit-eaters which also suck nectar from flowers.
Insect-eating bats include the Brazilian free-tailed bat Tadarida brasiliensis, found in vast numbers in the Carlsbad Caverns in New Mexico. Between 5,000-10,000 of these bats can emerge from the caves in a single minute.
Because bats sleep during the daytime, they avoid the desert╒s heat almost completely.
Camels
The ╘ship of the desert╒ is the mammal that most people associate with deserts. Like antelope, sheep and goats, camels are odd-toed ruminant mammals (family Camelidae), but their feet are not hooved ╨ instead they have nails. The camel family also includes the llama and alpaca of South America.
There are two main species of camel: the single-humped dromedary Camelus dromedarius and the two-humped bactrian camel Camelus bactrianus. Only the bactrian camel is still found in the wild ╨ the dromedary is only found in its domesticated form. As more and more of the nomadic peoples of northern Africa and Arabia settle in a single place, the dromedary is becoming less common ╨ its advantages are as a beast of burden and it provides few services to non-nomadic tribes.
Camels are adapted to life in the desert in several ways. They have long eyelashes which keep the sand out of their eyes, and they can also close their nostrils for the same purpose. Camels produce concentrated urine and dry dung, conserving water, and can lose up to a third of their body fluid without serious harm. They have humps made of fat (NOT water!) that can be used to provide energy when food is scarce. They have long legs which keep their bodies far away from the scorching desert sands, and their body temperature can fluctuate by as much as 11íF without killing the animal.
Cats
Several species belonging to the cat family (Felidae) are found in desert environments. The lion (Panthera leo) is sometimes seen in the Kalahari and Namib deserts of southern Africa, where it can obtain moisture from the blood of its prey. The caracal Felis caracal is Africa╒s version of the lynx. It lives in arid and dry savanna areas of Africa (also in southwestern Asia), preferring arid bush and preying on reptiles and small mammals as well as larger game such as antelope, sheep and even ostrich. Caracals are agile enough to catch birds ╨ even sometimes when the bird is in flight! This powerful cat is only 2╨3 feet in length and usually weighs less than 40 pounds. Caracals sleep in caves or rocky crevices during the daytime and are usually active at night and at twilight.
Cats are also found in the American southwestern deserts. The bobcat Felis rufus and the mountain lion Felis concolor are both seen in rocky terrain where sufficient game is available. Bobcats eat rabbits and hare as well as mice and squirrels. Also called the puma or cougar, mountain lions are strongly territorial hunting animals that usually live only in areas where they can prey on large animals like deer, coyotes and racoons.
Sandcats are found from Africa across to southwestern Asia. The numbers of these small cats have been drastically reduced by hunting.
Dogs
Dogs (family Canidae) include wolves, coyotes, jackals and foxes. Desert foxes usually sleep during the day and come out to hunt for small animals at night. They include the kit fox Vulpes macrotis of the USA, also found in grassland and mountainous areas up to southern Canada. The fennec fox Vulpes zerda and sand or Ruppell╒s fox Vulpes pallida are found in Africa, eating all kinds of small animals from insects to small antelope. Sand foxes have furry soles on their feet which help them walk or run on soft sand.
Coyotes (Canis latrans) live in much of midwestern and western North America. These swift-running animals are cunning and intelligent animals which usually live in packs and can often be heard howling in the night time desert. True scavengers, coyotes will eat almost anything ╨ from rabbits to berries and even dead animals.
Spotted hyenas live in several African regions, including the Namib desert. These pack animals are adapted to be able to eat several meals very quickly and then to go for long periods without feeding. This so-called ╘feast or famine╒ existence enables the hyena to live in an area where food may be scarce at times.
Giraffe
Although not usually considered as true desert animals, giraffe (family Giraffidae) are sometimes seen in on the semi-arid fringes of the southwestern deserts of Africa where trees are present. Giraffe are the biggest ruminant animals, and their long necks allow them to browse high in vegetation that smaller animals cannot reach.
Giraffe live in herds, probably for protection. Around 50-75% of all giraffe calves fall prey to lions and hyenas
Goats and sheep
Like antelope, goats and sheep belong to the family Bovidae and are ruminant hoofed mammals with hollow horns. Sheep and goats have been domesticated for thousands of years and are found in deserts in both the wild and domestic forms.
The main species found in the American deserts is the desert bighorn sheep Ovis canadensis. These animals do not live in the desert scrubland ╨ they inhabit desert mountain ranges close to permanent water sources. Bighorn sheep spend the day alternately feeding and chewing the cud, and sleep at night in favorite bedding spots. These sheep are wary, and have a keen sense of sight which they use to detect danger.
Desert bighorns are well adapted to rocky cliffs and mountains ╨ they can leap and climb quickly, and do not need to drink very often.
Hares and rabbits
Hares and rabbits belong to the order Lagomorpha, and are characterised by their long back legs and ears. Several species are found in the deserts of the American southwest, including the desert cottontail Sylvilagus audubonii and the larger black-tailed jack rabbit Lepus californicus.
Whereas these two rabbit species are found outside of desert areas, the antelope jack rabbit Lepus alleni is only found in the southern Arizona and New Mexico deserts. This jack rabbit╒s long ears play an important part in regulating the animal╒s temperature ╨ the expanded blood vessels in the ears give off heat, cooling the rabbit down. These rabbits feed on grasses, prickly peat, mesquite and other desert plants.
Rabbits and hares are often eaten by the larger birds of prey and by desert cats.
Horses
Over 600 specimens of Przewalski╒s wild horse Equus przewalskii have been reared in captivity. These horses used to live in the Mongolian Desert but became extinct in the wild in the 1970s. Small and stout in appearance, Przewalski╒s wild horse is able to feed on tough grasses which would not be acceptable to domestic horses. Observation of small groups shows that in the wild they spend their days grazing on the limited grass available in the desert terrain, moving to a water supply at dusk.
Another member of the horse family is the zebra. Grevy╒s zebra is recognisable by its narrow stripes and large ears. This is the tallest of the zebra species, and it lives in the desert areas of eastern Africa.
Grevy╒s zebra needs less water than the more common southern zebra, and so is adapted to live in drier terrain.
Marsupials
Marsupials are mammals which give birth to embryos which must complete development in the mothers pouch, attached to a nipple. Most marsupials apart from rare exceptions like the American opossum live in Australasia. Desert marsupials include the kangaroos (family Macropodidae) ╨ these have a rather similar lifestyle to the African gazelles.
Red kangaroos are found all over Australia, including desert regions. Kangaroos feed mainly at night, resting in the heat of the day. They can go without water for long periods, and although kangaroos are well adapted to cope with the desert environment they have increased in numbers due to the creation of grassland for sheep farming. The natural enemies of the kangaroo ╨ Tasmanian wolves ╨ are now extinct in mainland Australia, aiding the increase in the kangaroo population.
Meerkat
Meerkat (Suricatta suricatta) share the family Viverridae with the mongooses. They are social animals which live in communal burrows in the Kalahari desert of southern Africa. Meerkat prefer dry open country, and often share their dens with yellow mongooses and ground squirrels. Their main food source is buried invertebrate animals, including beetles, crickets, scorpions, spiders, and moths.
Meerkats are preyed on by hawks and eagles. Some individuals stand lookout from a nearby vantage point, barking to the other meerkat when danger is sensed. They usually run from danger or may put on a threat display to deter ground predators.
Rats and mice
Rats and mice (families Cricidae ╨ New World; Muridae ╨ Old World) are among the most common desert mammals. Their small size enables them to dig and live in underground burrows to escape the heat, and some species like the kangaroo rat (Dipodomys species) and gerbil Gerbillus gerbillus can survive without drinking water for long periods. Rodents also conserve water by not sweating.
Kangaroo rats get their name from their long back legs which they use to hop about. These animals conserve water by concentrating their urine as much as five times more than human beings. A number of species are found in the American southwestern deserts. The related Australian hopping mouse has urine that is ten times as concentrated as that of humans.
Dwarf hamsters live in the deserts of Mongolia and China. This small rodent has thck fur to protect it from the cold of winter. Like pet hamsters, dwarf hamsters have cheek pouches which they use to carry seeds and other food back to their burrows.
Squirrels
Ground-dwelling varieties of squirrel and chipmunk (family Sciuridae) are commonplace in desert terrain, and seven or eight different species may be seen in the American southwestern deserts. These include the rock and ground squirrels (Spermophilus species) and the antelope squirrels (Ammospermophilus species).
Squirrels are daytime animals which feed chiefly on seeds, fruit, green vegetation and insects. Some, like Harris╒ antelope squirrel Ammospermophilus harrisii live in burrows in the arid desert and drink only rarely ╨ they get most of their moisture from food sources. The white-tailed antelope squirrel Ammospermophilus leucurus forages for food on the ground as well as in yucca and cactus plants ╨ this species lives as far north as southern Oregon and Idaho and hibernates during winter in the northern part of its range.
