Eurasia is the largest land mass on earth,
stretching halfway around the globe from the British Isles to the Pacific
Ocean, and from the Bering Sea south to the tip of Malaysia, an area of 54
million sq km (21 million:sq -л»ХА few of its animal species, especially
those in the north, are closely related to, and in some instances are the same
as, those of North America.
Relatively recently, as earth time is
measured, Eurasia was linked to America
by a land bridge which spanned what is now the Bering Straits. This causeway
existed for thousands of years during the Ice Ages, when much of the earth's
water was locked up in glaciers, thus lowering sea level. Animals crossed back
and forth between the two continents on the land bridge, and the first human
settlers in America
probably arrived via this route.
About ten thousand years
ago, the latest in a series of ice ages came to an end. The ice melted; the
seas rose, and the Bering land bridge was submerged. Animal species which had
wandered west into Eurasia or east to America were isolated from their
native homelands. But because ten thousand years is a mere eye wink in
evolutionary timekeeping, very few changes have had time to take place in these
exiles. For example, the largest member of the deer family lives in the taiga
of both Eurasia and America.
In Eurasia it is called an elk, in America, a moose. But it is one and
the same animal. This is also true of another deer, the caribou, or reindeer.
The former is a wild animal of America;
the latter has been domesticated for centuries by the Lapps of northern Europe.
The Bering land bridge was probably
responsible for the survival of at least one species — the horse. This animal
originated in the western hemisphere, where it developed from a tiny,
three-toed creature, to the form very much like the one we know today. During
the Ice Ages, it migrated across the land bridge into Asia,
where it thrived. In America
the horse became extinct and didn't reappear here until the Spaniards brought
it back as a domesticated animal in the 16th century.
The Spanish horses, as
are all domestic breeds, were descendants of the wild horses which migrated
That original breed still exists. It is called Przewalski's horse, named for
the naturalist who first brought specimens to Europe from the grasslands of Mongolia. This
is the only true wild horse left in the world. All other so-called
"wild" horses are feral animals, that is, horses descended from
domestic animals which escaped from or were released by their owners.
Przewalski's horses once existed in large herds, but human intrusion into their
habitat pushed them farther and farther back into a harsh environment where
even these tough animals could not survive.
They were last seen in the wilderness in
1967. Fortunately breeding groups existed in zoos and reserves. Captive
propagation brought the population up to about 700 by 1985, and four dozen
Przewalski's horses have been born at the San Diego Zoo and the San Diego Wild Animal
Park. Several of the
Zoological Society's Przewalski's horses are on breeding loans to other zoos.
The Eurasian bison, called a wisent, is
closely related to the American bison. Although never so numerous as the
American member of the species, wisent used to roam the forests which covered western Europe. Centuries
of cutting destroyed all but a small remnant of these forests and came within
17 animals of exterminating the wisent. A captive breeding program saved them
and today a few hundred live in the Bialowieza
Forest in eastern Poland. The San
Diego Zoo has produced 25 calves.
If the felling of Europe's
forests meant the destruction of many wild animal species, it worked to the
advantage of others. Deer, for instance, have thrived and live from the British Isles eastward. Red, roe and fallow deer live in
western Europe, sika deer in Japan.
Pere David's deer, formerly a native of marshy areas in central China, is
extinct in the wild. It exists only in zoos and reserves.
The hedgerows of western Europe house many
small animal species. There are foxes, rabbits, hares, badgers, ferrets,
squirrels and birds. These and other animals have adapted to life in a
human-dominated environment. Starlings and sparrows, for example, do so well
that they are considered "pest" birds. Until recently, one of Europe's largest birds, the white stork, even nested in
the smaller towns and villages. The bird was considered a symbol of good luck,
and home-owners built platforms on rooftops for its nests. This practice is no
longer common and the stork avoids the towns.
The most regal of Eurasia's
raptors is the golden eagle, and the bird has figured in history for centuries.
Its image was carried by Roman legions as they conquered much of the
continent. During the Middle Ages, lesser members of royalty were free to use
other raptors for falconry, but the eagle was reserved for the king. Today, in
more remote parts of Asia, the golden eagle is
used to hunt wild goats, gazelles, foxes, and wolves. The bird occurs in the United States,
where it is under federal protection. It can be seen in San
Diego's back country and often is observed soaring over the San Diego Wild Animal
Several other northern Eurasia predators
are found in North America — falcons, hawks
and owls; mammals including wolves, wolverines and foxes. aHowever, two mammalian predators are
unique to I the Old World — leopards and
tigers. Leopards range i from northern Asia into Africa; tigers live only in
Asia I from Manchuria southward into India
There are five races of this great cat; all of them are endangered. The Zoo
enjoys considerable success breeding and raising Siberian tigers, of which the
total world population is only about 750 individuals. More than two dozen cubs
have been born and raised at the Zoo.
South of the taiga, Eurasian biomes become
less clearly defined. Much of the area is flat and treeless. In the west, where
rainfall is adequate, grass grows thickly. But deep in the continent's
interior, the land becomes a desert. Here, thousands of miles from the
moderating effects of the ocean, temperatures can climb well above 38°C (100°F) in summer, and plummet
far below freezing in winter.
Animals must make drastic adjustments to
these climatic extremes. One of the most common is migration. Herders move
their domestic herds and flocks, following the seasons, and many of the wild
grazers also make similar journeys, with predators following along.
The animals which are permanent residents
have adapted to the heat, cold and aridity of this area. The saiga, an
antelope-like animal, has nostrils pointing downward to help keep out dust.
Inside each of its nostrils the saiga has a sac which is believed to warm and
moisten the air.
The Bactrian camel of Mongolia and China has adapted to its environment
by growing a thick, shaggy, winter coat; broad, split hooves to keep from
sinking into the sand; and two humps for storing fat when foraging is poor.
Several species of wild asses are native
to the interior of central Asia. Among these
are the Mongolian kulan and Iranian onager. Asses are smaller than true horses
and characterized by long ears, deep-set eyes coarse, wiry manes, small feet
and tails tipped with long hairs. They can survive longer without water than
other members of the horse family and are able to get along on a small amount
of food. Because of their sure-footedness and endurance they are valuable
beasts of burden and have been domesticated for centuries.
The Eurasian grassland is home to the
heaviest of all flying birds, the 20
lb) great bustard. And the world's smallest crane, the
demoiselle which stands just 1 m
tall, breeds on grasslands from southeastern Europe into central Asia.
Several species of wild sheep and goats
live on the grasslands and adjacent mountains. Markhors and turs, both goats,
range from Spain to India and northward into Mongolia and Siberia.
The tahr, a goatlike animal, is found in the high Himalayas.
Goats differ from sheep in that they have beards, feet with scent glands,
convex foreheads, and a definite odor among the males.
Some of the world's most unusual mammals
live in the mountains which separate central Asia from India. One of
the best known is the giant panda, once considered a member of the raccoon
family and now thought to be related to bears. This animal lives on a diet
consisting mainly of bamboo shoots. For unknown reasons the bamboo is dying,
which threatens the pandas' future. The Chinese government has commissioned a
team of biologists to study the situation. Although giant pandas have rarely
reproduced in western zoos, a number of babies have been born in the Beijing zoo through
natural conception, and artificial insemination has recently been successful.
The giant panda shares its bamboo forest
with the lesser panda. This animal looks like a raccoon but is related to the
Central Asia is isolated from India and Burma
by the Himalaya mountain range, the highest
mountains on earth. The area is so remote that little is known about the
behavior of many of its animals. It is the home of a collie-sized gazelle,
several species of wild sheep, and a member of the cow family, the yak. The yak
is also domesticated and has been a beast of burden and supplier of milk, wool
and fuel for many centuries.
One of the most beautiful of all Himalayan
animals is the snow leopard, or ounce. Its fur is in great demand and poaching has placed it in grave
danger of extinction.
The snow leopard's main prey is the
bharal, or blue sheep, which lives in the Himalayas and other high mountains in
As one moves south from the high country,
the character of the land and its animals change. Rugged mountains give way to
forested foothills. This country is the northern edge of the sloth bear's range
which also includes other parts of India
and Sri Lanka (Ceylon).
Termites are a part of the sloth bear's diet, and it sucks them in by a
"vacuuming" process. The bear rips open the termites' nest with its
claws, then blows away the dirt and dust, and starts sucking. Its lips
protrude; its nostrils close to keep out dirt.
Beyond the foothills, seasonal forests
give way to semi-arid plains and desert in India. Axis deer, nilgai (India's largest
antelope) and blackbuck live here. In the Gir
Forest is the last remnant population
of the lions which once roamed from the Atlantic through the Near East and into
Asia. But lions have been gone from most of
this range for many centuries and exist today only in a protected reserve in
the tiny Gir Forest in western India, where a
few hundred individuals survive.
Where one finds lions and other predators,
scavengers will also be found. In India they include striped hyenas,
foxes, dholes (wild dogs), and Indian white-backed vultures. These animals
perform a vital function in the balance of nature, cleaning up carrion left by
the hunters, thus helping to prevent the spread of disease.
Still farther south lies India's
tropical forest, actually two of them — a rain forest and a seasonally deciduous
forest. They are home to a large variety of monkeys, mainly of two groups —
the short-tailed, stout-bodied macaques, which are primarily terrestrial, and
the long-tailed, slender-bodied arboreal langurs.
The macaques include the rhesus monkey of India, sacred
to the Hindus, and critical to science. The existence of the Rh blood factor
was first demonstrated in rhesus monkeys, and a rhesus was the first living
being shot into space in the United
States' space program. In Europe, the only
wild monkeys are the Barbary apes, actually macaques, of Gibraltar.
Legend has it that when these animals disappear — there are approximately 30 of
them — Britain's
reign over the Rock will come to an end.
The second large group of Asian monkeys,
the lan-gurs, are also called leaf-eating monkeys. There are more than a dozen
species, among which the douc langur is considered to be one of the most
beautiful of all monkeys. The word "douc" means "monkey" in
Three of the surviving five species of
rhinoceroses live in southeastern Asia. Two,
the Sumatran and Javan rhinos, could be extinct in the wild. The third, the
Indian rhino, exists in small numbers in Assam. Because of the heavy folds
of skin and the bumps, called tubercules, on its hips and shoulders, this rhino
appears to be wearing a suit of armor.
The Chinese believe that rhino blood,
urine, and horn (which is not a true horn at all, but is composed of hair-like
material) have medicinal and aphrodisiacal powers. This superstition has
resulted in heavy poaching of rhinos, placing them in grave danger.
Among the better-known snakes of
southeastern Asia are the Indian and king
cobras and the pythons. A king cobra can measure 3.5 m (12 ft) or more. It feeds
mainly on other snakes. The closely related Indian, or Asian, cobra is
appreciably smaller. The pythons are non-venomous constrictors. Contrary to
popular belief they do not crush their victims to death but, through
constriction, cause death through suffocation.
Southeastern Asia is the home of some of the showiest of
all birds — the pheasants. Although native to Asia,
they have been introduced elsewhere and now are among the most widely
distributed of birds. One of the most widespread is the ringneck pheasant. An
old legend claims that ringnecks were introduced into Greece by Jason, famous for his
quest of the golden fleece. Ringnecks were brought to the United States in the mid-1800's and
are now game birds. Several species of pheasants are exhibited at the Zoo, two
of them roaming freely on the grounds.
The first is the blue peafowl. The male,
called a peacock, is the traditional symbol of vanity and false pride because
of its almost constant displaying and strutting. The peafowl has been
semi-domesticated for ages. A Greek myth relates how the bird got the eye-like
spots on its tail. The peacock was a favored pet of Juno, wife of Jupiter. She
became angry at her one-hundred-eyed
servant, Argus, because of a misdeed on his part. To punish him and to make
sure the world remembered his offense, she snatched out his hundred eyes and
scattered them on the tail of her pet peacock. There they remain to this day.
The other pheasant that wanders the Zoo
grounds is the junglefowl. It looks much like a domestic chicken —
understandably since it is the chicken's ancestor.
Anthropologists think the chicken was
first domesticated about 4000 B.C. as a fighting bird. Evidence suggests that
the first chickens in the New World came with
Polynesian sailors. The most ornamental of all domestic chickens are the
long-tailed birds bred by the Japanese, some having tail feathers 6 m (20 ft) long.
The hot, humid rain forests of
southeastern Asia hold a profusion of
wildlife, much of it arboreal. Among these tree dwellers, primates reign, and
within this group, the anthropoid — manlike — apes are royalty. Two of earth's
four kinds of manlike apes live in southeastern Asia.
The smallest and most
agile of these are the gibbons and siamangs. These apes are light-bodied, long-armed and have long, slender hands. Their
generic name, Hylobates, means "tree dweller." They are truly
champion acrobats, swinging hand over hand and leaping more than 9 m (30 ft) from one branch to the
next. On large branches they usually walk upright, holding their arms aloft for
balance. Gibbons live in family groups of two to six animals within well
defined territories. Their morning whooping, often heard at the Zoo, is a
territorial call to warn off other gibbons. The second anthropoid of southeastern
Asia is the slow, retiring orangutan. Its name
means "old man of the forest," and the orang does seem the most human
of the apes. Unlike the gibbon, it is a loner. The species used to be
widespread throughout the islands of southeastern Asia but extinction came
early on all but Borneo and Sumatra. If we
read the evidence correctly, prehistoric man hunted orangutans for food and
could have been partly responsible for their disappearance from most of the
range. Today fewer than 5,000 individuals remain, and despite strenuous efforts
to save them, their numbers continue to drop. The forests they need are falling
to the ax, so if the species survives, it will be in zoos and wildlife
Among the rain forest's arboreal
creatures, there are a number of interesting "flying" animals —
snakes, frogs and lizards. None of these animals actually flies. They glide
with varying degrees of aerodynamic facility. The snake spreads its ribs and
arches its body to produce a crude airfoil that allows it to glide at a steep
angle. The other animals have folds and strips of skin which, when stretched,
produce taut membranes that slow descent.
The second largest of all land animals,
the Asian elephant, lives in the tropical forest. A bull can weigh 5,000 kg (11,000 Ib) and
stand 2.5 to 3 m
(8 to 10 ft)
tall at the shoulders. Asian elephants have been domesticated for centuries —
for riding, war, and as beasts of burden.
The Asian elephant's only natural enemy is
the tiger. Although this cat attacks elephants, especially calves, it also
preys on just about anything it can catch, including the crocodiles that live
in the forest's sluggish rivers. One of its chief prey is the Malay tapir.
Tapirs originated in the New World,
crossed on the land bridge into Asia and now
exist on both continents. The obvious difference between Old World and New World tapirs is the large, white saddle-shaped patch
of hair on the Malay tapir's body. American tapirs are a solid brown color.
Of the many species of
birds in the tropical forest, among the most bizarre are the hornbills. There
are 45 species, distributed throughout tropical and subtropical Africa and Asia. One of the bird's more fascinating behavioral
habits is the manner of nesting. In most species of hornbills, when the female
is pregnant and ready to lay, she enters a natural cavity in a tree. She and
the male plaster over the cavity's opening with a mixture of droppings, mud and
regurgitated food. They leave a narrow opening just wide enough for the female
to poke her beak through, but too small for predators to enter. The plastered
wall hardens, and the female, her eggs, and later the chicks, are safe. The
male spends the time feeding his mate. When the nestlings are half-grown, both
parents chip away the wall and the female emerges. She then helps her mate feed
the baby birds, which remain in the nest until they are fledged. During the
time the nest is occupied, it is kept clean and disease-free by insects and