Reforestation


Reforestation is the growth of new trees in an area that has been cleared for human activities. It can occur naturally or be initiated by people.

Many areas of the eastern United States, such as the New England region, reforested naturally in the nineteenth and early twentieth centuries after farmland that had been abandoned was allowed to lie fallow for decades.


Slash and Burn Agriculture


Slash-and-burn agriculture, also called swidden agriculture, is a practice in which forestland is cleared and burned for use in crop and livestock production. While yields are high during the first few years, they rapidly decline in subsequent years, leading to further clearing of nearby forestland.

Slash-and-burn agriculture has been practiced for many centuries among people living in tropical rain forests. Initially, this farming system involved small populations.

Soil Contamination


Soils contaminated with high concentrations of hazardous substances pose potential risks to human health and the earth’s thin layer of productive soil.

Productive soil depends on bacteria, fungi, and other soil microbes to break down wastes and release and cycle nutrients that are essential to plants. Healthy soil is essential for growing enough food for the world’s increasing population. Soil also serves as both a filter and a buffer between human activities and natural water resources, which ultimately serve as the primary source of drinking water.

Soil that is contaminated may serve as a source of water pollution through leaching of contaminants into groundwater and through runoff into surface waters such as lakes, rivers, and streams.

Addax


The addax is a large antelope whose coat is gray-brown in winter and almost white in summer. Black hair sprouts from its forehead and from the end of its 10- to 14-inch (25- to 36-centimeter) tail. Two long, thin, spiral horns (each twisting two or three times) extend up and back from the front of the animal’s head.

An average addax measures about 5 feet (1.5 meters) in length and about 3 feet (1 meter) in height at its shoulder. It weighs between 132 and 287 pounds (60 and 130 kilograms). A female addax usually gives birth to one infant after a gestation (pregnancy) period of eight to nine months.

Giant Armadillo


The giant armadillo is the largest member of the armadillo family, which is composed of twenty–one species. Eleven to thirteen moveable bony plates cover a giant armadillo’s back, and three to four flexible bands cover its neck.

Its body is dark brown, while its head, tail, and a stripe around the bottom of its shell are whitish. A giant armadillo measures 30 to 39 inches (76 to 99 centimeters) from the tip of its nose to the end of its body. Its tail is about 20 inches (50 centimeters) long. It weighs between 44 and 88 pounds (20 and 40 kilograms).

African Wild Ass


The African wild ass is one of only seven surviving species of equids (horse family). Of these seven species, five are threatened or endangered. The smallest member of the horse family, the African wild ass stands about 4.5 feet (1.5 meters) tall at the shoulders and weighs about 550 to 600 pounds (250 to 275 kilograms).

It has a gray coat with a white belly and a dark stripe up its back. With its long ears and short stubby mane, the African wild ass looks like its cousin, the American domestic donkey, and is in fact the donkey’s ancestor.

Aye-aye


The unusual-looking aye-aye is covered with a coat of coarse blackish-brown hair, which overlays a denser coat of short white hair. The animal has very large, sensitive ears that stick out from its small, rounded head. It has sharp, rodent-like incisor (front) teeth and long, claw-like fingers and toes.

An average aye-aye is 15 to 18 inches (38 to 46 centimeters) long from the top of its head to the end of its body. Its bushy tail measures 16 to 22 inches (41 to 56 centimeters) long. The animal weighs between 4.4 and 6.6 pounds (2 and 3 kilograms).

Golden Bandicoot


The golden bandicoot belongs to the order of mammals known as marsupials, whose young continue to develop after birth in a pouch on the outside of the mother’s body. The animal’s coarse fur is a mixture of yellow-orange and dark brown hairs, giving it a golden appearance.

It has a long, tapering snout and short, rounded ears. An average golden bandicoot measures 9 to 19 inches (23 to 48 centimeters) from the top of its head to the end of its body and weighs about 3 pounds (1.4 kilograms). Its tail is 3 to 8 inches (8 to 20 centimeters) long.

Gray Bat


Contrary to its name, the gray bat is reddish-brown in color. Its forearm measures 1.6 inches (4 centimeters) long, and it weighs 0.35 ounce (10 grams). The gray bat differs from other species of the Myotis genus (a group with similar characteristics) in that its wing membrane (a double membrane of skin) attaches to its ankle instead of the side of its foot.

The gray bat feeds at night on insects, particularly mayflies and mosquitoes. It roosts in two different types of caves throughout the year.

Townsend’s Big-eared Bat


The Townsend’s big-eared bat is named for its large ears, which are from 1 to 1.6 inches (2.5 to 4 centimeters) long. In contrast, the bat’s body length is 1.8 to 2.7 inches (4.5 to 7 centimeters), its tail length is 1.4 to 2.1 inches (3.5 to 5.3 centimeters), and its forearm length is 1.4 to 2 inches (3.5 to 5 centimeters). The average Townsend’s big-eared bat weighs between 0.18 and 0.46 ounce (5 and 13 grams).

Townsend’s big-eared bats feed primarily on moths, which they locate through echolocation (sonar). In this process, a bat emits high-pitched sounds that echo or bounce off its prey. The bat’s sensitive hearing picks up the echo. From that sound, the bat can determine the size, shape, and location of its prey.

Grizzly Bear


The grizzly bear, a subspecies of the brown bear (Ursus arctos), is one of the largest land mammals in North America. An average male grizzly has a head and body length of 6 to 8 feet (1.8 to 2.4 meters), stands 3.5 to 4 feet (1 to 1.2 meters) at its shoulder, and may weigh up to 800 pounds (360 kilograms).

The smaller female grizzly weighs between 200 and 400 pounds (90 and 180 kilograms). The grizzly bear is so-named because its thick, light brown to black fur is streaked with gray, giving it a “grizzled” look. Grizzly bears have short, rounded ears, humped shoulders, and long, curved claws.

Sun Bear


The smallest member of the bear family, the sun bear has an average head and body length of 3.5 to 4.5 feet (1 to 1.4 meters). Its shoulder height is 26.6 inches (67.5 centimeters) and its weight is between 60 and 140 pounds (27 and 64 kilograms).

The animal’s short tail extends only 1 to 3 inches (3 to 7 centimeters). The fur on the sun bear’s body is very short and black; the fur on its muzzle is almost white. Most animals of this species have a white to yellow-orange horseshoe-shaped marking on their chests.

The sun bear’s curved and pointed claws make it an excellent climber. It spends most of its day sleeping or sunning on a platform it builds in trees 7 to 20 feet (2 to 6 meters) above the ground.

American Bison


The American bison (commonly known as the buffalo) has a massive body, humped shoulders, and pointed horns that curve up and in. In winter, its coat is dark brown and shaggy.

In the spring, this coat is shed and replaced by one that is short and light-brown. Hair on the head, neck, shoulders, and forelegs remains long and shaggy throughout the year. A beard also hangs from the chin of the animal’s huge, low-slung head.

European Bison


European bison (often called wisent, from the German word for “bison”) are the largest land mammals in Europe but are slightly smaller than their close relative, the American bison.

The adult male European bison weighs in the range of 800 to 2,000 pounds (400 to 920 kilograms); the female weighs from 650 to 1,200 pounds (300 to 540 kilograms). A good-sized male has a shoulder height of about 6 to 6.5 feet (1.8 to 2 meters) and his body is about 9 feet (2.75 meters) long. The head is very big, and both males and females have horns.

Wild Water Buffalo


The wild water buffalo, also known as the Asian or Indian buffalo, is a very large animal, averaging 7.75 to 10 feet (2.4 to 3 meters) long. It stands 5 to 6.25 feet (1.5 to 2 meters) tall at its shoulder and weighs between 1,550 and 2,650 pounds (700 and 1,200 kilograms). Long, coarse hair covers the buffalo’s ash gray to black body.

Both male and female water buffalo have small ears, thin faces, and widely spread horns. The horns, thick where they emerge from the animal’s head, form a semicircle by curving out and back. Ending in a point, these horns may reach a length of 6 feet (2 meters).

Bactrian Camel


The bactrian camel and the better–known Arabian camel (Camelus dromedarius) are the only two living species of true camel. Whereas the Arabian camel has only one hump, the bactrian camel has two.

An average bactrian camel stands 6 to 7.5 feet (1.8 to 2.3 meters) in height and weighs between 1,000 and 1,575 pounds (455 and 715 kilograms). The coat of a wild bactrian camel is short and gray-brown in color; that of a domestic or tame version of the animal is long and dark brown.

Cheetah


“Cheetah” comes from the Hindu word chita, meaning “spotted one.” Round black spots cover the cheetah’s tawny fur and a black streak runs down each cheek. An average cheetah measures 4.5 to 5 feet (1.4 to 1.5 meters) long and stands between 27 and 34 inches (69 and 86 centimeters) high at its shoulder. Its tail extends 24 to 32 inches (61 to 81 centimeters). It weighs between 80 and 145 pounds (36 and 66 kilograms).

Cheetahs are the world’s fastest land animal. They are capable of bursts of speed up to 70 miles per hour (110 kilometers per hour), but they usually cannot keep up this top speed for more than 1500 feet (455 meters).

Chimpanzee


Chimpanzees, gorillas, and orangutans are all considered great apes. Of the three, chimpanzees are the most closely related to humans. Chimpanzees and humans share 98 percent of the same genetic makeup.

In addition, the two groups share many social and psychological traits. Researchers have documented chimpanzees making and using tools, expressing complex emotions, forming bonds and friendships, and communicating using sign language.

An average chimpanzee stands 5 feet (1.5 meters) tall and weighs about 150 pounds (68 kilograms). Since its arms are longer than its legs, a chimpanzee walks on the ground using the soles of its feet and the knuckles of its hands.

Most of its body is covered with long, black hair. A chimpanzee’s hairless face can range in color from almost white to almost black. The hair around a chimpanzee’s face grays with age, and older chimpanzees often become bald.

Highly social mammals, chimpanzees live in communities made up of 30 to 60 members. During the day, the animals often travel on the ground. At night, they stay in nests they build in treetops.

A chimpanzee’s diet consists mainly of fruit, but they also eat insects, leaves, flowers, bark, seeds, tree resin, eggs, and meat. At times, chimpanzees band together to hunt animals such as antelopes and monkeys.

Mating between male and female chimpanzees takes place anytime during the year. Unlike many other animal species, female chimpanzees do not have to mate with the dominant male in their group. Instead, females often mate with males of their choosing.

After a gestation (pregnancy) period of 230 to 240 days, a female chimpanzee gives birth to a single infant. During the course of her life, an average female chimpanzee will give birth to fewer than five infants. Bonds between mothers and infants are very strong, and some last a lifetime.

Habitat and current distribution

A few centuries ago, several million chimpanzees existed in the equatorial regions of Africa. They inhabited a range of ecosystems, from dense forests to open savannas.

Now, estimates vary, but it is thought that there are between 200,000 and 225,000 chimpanzees in the wild, and many believe these estimates are high. Only 10 present-day African nations have chimpanzee populations above 1,000.

About 5,000 chimpanzees exist in captivity worldwide. Over one-half of these are used as subjects in medical research. The rest are zoo exhibits, entertainment props, and private pets.

History and conservation measures

Habitat destruction, disease, and expanding human populations have led to the decline in the number of chimpanzees. Mining has destroyed the chimpanzee habitat in the diamond districts of Sierra Leone and the iron districts of Liberia.

The cutting of forests for timber has destroyed the animals’ habitat in Uganda. And the conversion of forests into agricultural land has threatened chimpanzees in Rwanda and Burundi.

Certain laws prohibit the hunting and sale of chimpanzees, but these laws are not enforced. Many chimpanzees are caught and traded illegally. For each chimpanzee shipped overseas, ten die during transport due to mistreatment and malnutrition.

Two sanctuaries exist in Gambia and Zambia for orphaned chimpanzees and those seized from illegal traders. Most African nations have passed laws and have set aside areas to protect chimpanzees. However, as human populations in Africa continue to grow, many of these reserves may be used to fill human needs.

In 2003, a group of scientists and conservationists called for an upgrade in the status of chimpanzees from endangered to critically endangered. Data coming from Gabon and the Republic of Congo, where most of the world’s chimpanzees live, reveals that the ape population there has decreased by half between 1983 and 2000.

The reasons for the decline were continued hunting and outbreaks among chimpanzees and gorillas of the Ebola virus, a very deadly and contagious virus that was discovered in Africa during the 1970s and afflicts humans as well.

The group of scientists warned that chimpanzees and gorillas are in greater jeopardy of extinction than had been formerly realized. They called for greater enforcement of laws against hunting and capturing chimpanzees and an increased focus on research of the Ebola virus in primates.

Short-tailed Chinchilla


The short-tailed chinchilla is a nocturnal (active at night) rodent with soft fur, large ears, and a bushy tail. It is one of two species of chinchilla—the other is the long-tailed chinchilla (Chinchilla langiera).

An average chinchilla has a head and body length between 9 and 15 inches (23 and 38 centimeters) and a tail length between 3 and 6 inches (7.5 and 15 centimeters).

Malabar Large Spotted Civet


The Malabar large spotted civet is nearly identical to, or is in fact the same species as, the large spotted civet (Viverra megaspila). Adults of this species usually weigh about 18 to 20 pounds (8 to 9 kilograms).

Their long gray coats are mottled with large black spots. They have long tails banded in black and a black crest of long fur down their backs. Although most civets look like cats, the Malabar large spotted civet more closely resembles a dog with its long legs and dog-like head.

Musk Deer


Musk deer are so-named because the males of the species have a gland, called the pod, that develops in the skin of their abdomen. This gland produces a waxy substance called musk, which may be used by males to attract females.

An average musk deer has a head and body length of 28 to 39 inches (71 to 99 centimeters), stands 20 to 24 inches (51 to 91 centimeters) at its shoulder, and weighs between 15 and 40 pounds (7 and 18 kilograms). The musk deer’s hair is long and coarse. It varies in color from dark to golden brown, depending on the species.

Swamp Deer


The swamp deer is a large member of the deer family. The animal has an average head and body length of 4 to 6 feet (1.2 to 1.8 meters), measures about 4 feet (1.2 meters) in height at its shoulder, and weighs between 375 and 620 pounds (170 and 280 kilograms).

In winter, the swamp deer’s coat is brown on the top part of its body and paler on its underside. In summer, the entire coat lightens in color. Male swamp deer are often darker overall than females. Swamp deer feed on grasses and aquatic plants, and their main predators are tigers and leopards.

African Wild Dog


The African wild dog, also called the African painted wolf, has a streaked, multicolored coat. The tan, black, and white pattern varies between individual dogs, but each animal’s head is usually dark. An African wild dog has large rounded ears, which it uses to signal other dogs and to control body temperature by radiating (giving off) heat. Its 12- to 16-inch (30- to 41-centimeter) tail ends in a plume that is white-tipped.

The dog’s legs are long and thin. An average African wild dog has a head and body length of 30 to 44 inches (76 to 112 centimeters) and a shoulder height of 24 to 31 inches (61 to 79 centimeters). It weighs between 37 and 79 pounds (17 and 36 kilograms).

Chinese River Dolphin


The Chinese river dolphin, also known as baiji, is one of the most rare and endangered cetaceans (pronounced si–TAY–shuns; the order of aquatic mammals that includes whales, dolphins, and porpoises). It has an average overall length of 6.75 to 8.25 feet (2 to 2.5 meters) and weighs between 220 and 500 pounds (100 and 230 kilograms). Its body color is blue-gray on top and almost white underneath.

Chinese river dolphins have very poor eyesight, which is an evolutionary result of the muddy conditions of the water in which they live. Since the dolphins could not use their vision, they lost it over the course of time.

Dugong


Dugongs are very large sea mammals, sometimes called “sea cows.” They have been familiar to humans for centuries, particularly because, for some reason, these ungainly creatures gave rise to the mermaid myths of the past.

Adult dugongs, both male and female, range in size from 8 to 13 feet (2.4 to 4 meters). They weigh between 500 and 1,100 pounds (230 to 500 kilograms) and have a big roll of fat around their bodies. Dugongs are gray or rusty brown in color; their young, called calves, are born a creamy beige and then darken as they grow.

Although dugongs breathe air into their lungs like land mammals, they live in the ocean and never come onto land. They are able to stay underwater for up to about six minutes at a time, but their dives usually last only one to three minutes before they come up for air.

African Elephant


The African elephant is the world’s largest living land mammal. An average adult male stands 10 feet (3 meters) tall at its shoulder and weighs between 11,000 and 13,000 pounds (5,000 and 5,900 kilograms). Females are a little shorter in height and weigh about 8,000 pounds (3,600 kilograms).

The animal’s thick and loose skin is dark, muddy gray in color. Its large ears, up to 42 inches (107 centimeters) in diameter, hold many prominent veins. To cool its blood during the heat of the day, the African elephant flaps its ears vigorously.


Asian Elephant


Description and biology

The Asian elephant, also known as the Indian elephant, is smaller than its relative, the African elephant. An average male Asian elephant weighs up to 11,500 pounds (5,220 kilograms) and stands 8.5 feet (2.6 meters) tall at its shoulder.

Females of the species are slightly shorter in height and weigh up to 6,000 pounds (2,270 kilograms). The elephant has an arched back and a flat forehead. Its ears are smaller and its trunk shorter and smoother than those of the African elephant.

Black Footed Ferret


Description and biology

The black–footed ferret is a member of the weasel family (other members include weasels, martens, fishers, otters, minks, wolverines, and skunks). Similar in size to a mink, the back–footed ferret has a long, slender body covered in short, pale yellow fur.

On its throat and belly, the fur is nearly white. The animal has a brownish head, a brownish–black mask across its eyes, black feet and legs, and a black tip on its tail.

An average black–footed ferret has a body length of 18 to 22 inches (46 to 59 centimeters) and a tail length of 4.5 to 5.5 inches (11.5 to 14 centimeters). It weighs 18 to 36 ounces (510 to 1,021 grams).

Black–footed ferrets prey on prairie dogs and live in prairie dog burrows. They hunt at night and are rarely active above ground during the day. Ferrets also eat mice, voles, ground squirrels, gophers, birds, and insects. They are preyed upon by great–horned owls, golden eagles, coyotes, and badgers.

Ferrets are solitary animals. They move around a territorial range of about 100 acres (40 hectares), which they mark with musk from scent glands. Males often have a larger range than females. The two sexes come together only to mate in March and April. After a gestation (pregnancy) period of 41 to 45 days, a female black–footed ferret gives birth to three to five infants, called kits.

The kits do not come out of the burrow until they are six weeks old. Then the mother separates the kits into different burrows, where they learn to take care of themselves. By early fall, they are on their own. Most kits do not survive their first year, and most adult ferrets do not live more than a few years.

Habitat and current distribution

Black–footed ferrets once ranged throughout the Great Plains—from Texas to southern Saskatchewan, Canada, and from the Rocky Mountains to the Dakotas, Nebraska, and Kansas. Considered one of the most endangered mammals in the United States, the black–footed ferret did not exist in the wild between 1987 and 1991.

History and conservation measures

When American pioneers moved west across the plains in the nineteenth and early twentieth centuries, they destroyed prairie dog habitat in order to create land for livestock and agriculture. The use of poison and hunting and habitat destruction reduced the prairie dog population by 90 percent.

As prairie dogs and their habitat disappeared, so did the food sources and habitat for black–footed ferrets. A severe plague of canine distemper (viral disease) in the 1950s further reduced the small number of remaining black–footed ferrets.

Because no black–footed ferrets were found in the wild between 1972 and 1981, the animal was thought to be extinct. However, in 1981, a small population of ferrets was discovered near Meeteetse, Wyoming. The population increased over the next few years, but an outbreak of canine distemper in 1985 severely threatened the survival of the species.

In 1987, the U.S. Fish and Wildlife Service (USFWS) placed the last 18 known wild black–footed ferrets in a captive breeding facility. The goal of this program is to maintain a breeding population of black–footed ferrets in captivity and to return their offspring to the wild.

In 1991, 49 captive–bred, young ferrets were released into the Shirley Basin in Wyoming. Several of these animals survived the winter and bred successfully. Since 1991, 200 captive–bred ferrets have been released in Wyoming.

The captive breeding programs that followed have been highly successful. By 1998, the captive breeding programs were producing record–breaking numbers of kits, many of which were reintroduced to the wilderness. In 1998 alone, 94 kits were released in South Dakota’s Conata Basin/Badlands National Park.

Montana received 77 kits in two sites, Arizona received 29, New Mexico 7, and 10 went to an experimental area in Colorado and Utah. Ferrets have also been successfully released in the wild in Mexico. All of these reintroduced ferret populations have produced healthy numbers of litters in the wild.

Between South Dakota and Montana, an estimated 100 kits were born in the wild in 1998 alone. In the fall of 2002, ferrets were released at a new managed prairie dog/black–footed ferret site on the Rosebud Sioux Reservation in South Dakota.

The tribe has been active in conservation of the prairie ecosystems (the ecological community, including plants, animals, and microorganisms, considered together with their environment), and will take a leading role in ferret recovery on their lands, where a population of 200–400 ferrets is expected.

The U.S. Fish and Wildlife Service reports that there are limited sites in North America with suitable prairie dog populations to support the self–sustaining ferret population currently being released in the wild.

Further work on managing prairie dog populations and their habitat is needed in order to keep up the progress made on the recovery of the black–footed ferret in the wild.

Island Gray Fox


Description and biology

While the island gray fox is mostly gray, its belly and throat are white, and the sides of its neck and the underside of its tail are rust. Black markings often accent its face and limbs.

An average island gray fox has a head and body length of 20 inches (50 centimeters) and stands roughly 5 inches (13 centimeters) tall at its shoulder. Its tail can extend in length from 4.5 to 11.5 inches (11.4 to 29.2 centimeters). It weighs between 3 and 6 pounds (1.3 and 2.7 kilograms).

The island gray fox hunts for food primarily in the early morning and late evening. Insects and fruits constitute the main portion of its diet, with small mammals, birds, reptiles, and eggs making up the remainder.

Male and female foxes come together to mate between December and March. A female island gray fox usually gives birth to a litter of one to eight pups after a gestation (pregnancy) period of 50 to 60 days. The mother nurses her pups for six weeks while the father hunts for food in a range of about 3 square miles (7.7 square kilometers).

Habitat and current distribution

The island gray fox lives in a variety of habitats, including grassland, coastal scrub, sand dune, and forest areas. It is found only on the six largest Santa Barbara Islands (also known as the Channel Islands) that extend along the southern coast of California.

Scientists believe that the Channel Islands split off from mainland California some 11,500 years ago and that the islands then broke apart from each other over the next 2,000 years. The island foxes evolved separately from mainland foxes and from each other, forming unique subspecies on each island.

History and conservation measures

A study of island gray foxes was begun in 1993 by biologists (scientists who study living organisms) on San Miguel Island. This has revealed that the population of island gray foxes on the island has declined from 450 animals in 1994 to fewer than 40 animals.

It is believed that similar declines have occurred on the other islands. Destruction of its limited habitat is the main threat to the animal’s continued existence. Other threats include competition for food from feral (once domesticated, now wild) cats and possible diseases from domestic dogs.

The remoteness of the Santa Barbara Islands makes protection of the island gray fox difficult. The U.S. Navy is attempting to eliminate feral cats on the islands of San Clemente and San Nicolas. Also, the Los Angeles Zoo is considering establishing a program to breed island gray foxes in captivity.

Dama Gazelle


Description and biology

The dama gazelle, a graceful antelope found in the Sahara Desert region of Africa, has long legs, a long neck, and ringed horns curved back in the shape of a lyre (musical instrument). Its neck and a portion of its back are reddish brown in color, while the rest of its body is white (including one spot on the inside of its neck).

An average dama gazelle has a head and body length of 40 to 67 inches (102 to 170 centimeters) and measures 35 to 42 inches (89 and 107 centimeters) high at its shoulder. Its tail, white with a black tip, extends 9 to 12 inches (23 to 30 centimeters). The animal weighs between 90 and 185 pounds (41 and 84 kilograms).

Like most species of gazelle, the dama gazelle has keen senses of hearing and smell. It grazes on shrubs and trees such as acacia and desert date. This gazelle travels alone or in small groups in search of food. A female dama gazelle gives birth usually to one infant after a gestation (pregnancy) period of 160 to 220 days.

Habitat and current distribution

Once populous in the countries of Libya and Morocco, the dama gazelle is now virtually extinct in northern Africa. The animal currently ranges across several countries in central and western Africa. A few thousand are found in Mali, Chad, and Niger. Only very small and scattered populations survive in other African countries.

In its range, the dama gazelle inhabits the arid (dry) grassy zone between the Sahara and the Sahel (an semiarid area south of the Sahara). It prefers to live on stony or rocky terrain, especially around the edges of hills.

History and conservation measures

Like many other gazelle species, the dama gazelle is vanishing from its traditional range because of illegal hunting, habitat destruction, and competition for food from domestic livestock.

Although protected areas exist in the dama gazelle’s range, such as the Ouadi Rime–Ouadi Achim Faunal Reserve in Chad and the Aïr and Ténère National Nature Reserve in Niger, they afford the animal little security. Illegal hunting, especially from motor vehicles, occurs inside and outside the reserves.

The need to feed an expanding human population also threatens the animals. Dama gazelle habitat is disappearing as irrigation and other agricultural methods have turned African deserts and grasslands into farmland.

Facing competition from grazing livestock, dama gazelles have been forced to move south of their usual range in search of food. Such movement has brought the animals into even greater contact with humans. The result has been increased hunting.

The future of the dama gazelle is not certain, but some recovery programs are underway. The species was extinct in Senegal, but it has been reintroduced there. By 1997, there were at least 25 animals living in Senegal as part of a semicaptive breeding program.

Hoolock Gibbon


Description and biology

Gibbons are apes, related to gorillas and chimpanzees, but they are known as “lesser apes” because of their small size. There are 13 or more kinds of gibbons. Hoolock gibbons are the second–largest kind, generally growing to about 13 pounds (6 kilograms).

Adults are about 24 to 35 inches (60 to 90 centimeters) long and have no tail. Male hoolocks have black fur with white eyebrows, while females have beige or red–brown fur with dark brown eyebrows and cheek areas.

Gibbons are amazing acrobats when it comes to brachiating, or swinging by their arms among the treetops. Hoolocks’ bodies are built for this movement. They have very long arms and long, hook–shaped hands.

They swing by their arms from one branch to another, with their hand forming a hook on the limb. They are capable of leaping long distances through the air from branch to branch or running atop the leaves in the treetops. Their diet is made up mainly of fruit and leaves, along with some insects and flowers.

Figs are a favorite food. Hoolocks are diurnal, meaning they roam the forests during the day and sleep at night. A family of hoolocks generally sleeps sitting up in one or two favored treetops. When they need to come down from the trees, hoolocks walk on two feet in an upright position.

Most gibbons live in family units consisting of two parents with several immature offspring. They are monogamous (when the male and female become partners, they remain together for life).

Gibbons generally give birth to one offspring at a time. Baby hoolock gibbons are born with no hair and depend upon their mothers for warmth. The offspring usually stay with their parents until they are six to nine years old and have reached sexual maturity.

Each gibbon family group lives within its own specific territory, usually about 30 to 50 acres (12 to 20 hectares) in area, which they defend from the intrusion of other gibbons. The life span of a gibbon in the wild is not known, but is probably about 30 to 40 years.

Hoolocks, like other gibbons, are very musical mammals, with a distinctive form of vocal communication displayed in half–hour–long morning songs performed by the family each day.

The male and female partners sing a kind of duet together, and then other members of the family may join in to sing solos. These morning songs communicate to other gibbons that the hoolock family’s area is claimed and will be defended, and may also serve as mating calls from the younger family members.

The folklore of the indigenous (native) people of Southeast Asia includes many stories about this magical music of the rain forests. Unfortunately, these morning songs also inform hunters of the location of the gibbon families.

The only known enemy to hoolock gibbons is the human being.

Habitat and current distribution

Gibbons have lived in the forests of Southeast Asia for millions of years. The hoolock is found in tropical (a climate warm enough year–round to sustain plant life) and subtropical evergreen forests, and in mountain forests produced by seasonal monsoons (heavy rainfalls accompanying high winds).

Curently hoolocks live in Myanmar (formerly Burma), Bangladesh, the northeastern part of India, and the southwestern part of China. There are two subspecies of hoolock gibbons, the eastern and western. They are divided by the Chindwin River in Myanmar. Hoolocks range from the Brahmaputra River (in Bangladesh, India, and China) on the west to the Salween River (in China and Myanmar) on the east.

History and conservation measures

The habitat in which hoolock gibbons live is shrinking rapidly. The tropical and subtropical forests are being cut down and burned in order to make way for tea plantations and other crops, for logging and taking out other fuel, and also for human settlement.

As their habitat is fragmented by the clearing of forests, hoolock gibbons become more vulnerable to humans, since they must come down from the treetops to cross from one food source to the next.

Humans hunt hoolocks for food and to sell as pets, and gibbon bones and meat are valued in some traditional Asian medicines. Among some groups in Myanmar, for example, it is believed that eating the dried hands and legs of hoolocks will promote fertility (the ability to have children) in women.

In 1977, biologists (scientists who study living organisms) estimated the hoolock gibbon population at more than 500,000 animals. Ten years later, it was down to 170,000.

By 2000, the hoolock gibbon population had been severely reduced. In India (where there were about 80,000 hoolocks in the early 1970s), there were only about 5,000 animals in 2000; there were less than 200 hoolocks in China, and 200 in Bangladesh. There is no current data about hoolock gibbons in Myanmar.

Preserving the remaining rain forest habitat and eliminating hunting of hoolock gibbons are key factors in the effort to save the species from extinction in the wild. Since the 1990s, some sanctuaries and reserves have been created within hoolock gibbon habitats.

China and India have laws protecting gibbons, but the enforcement is not strict and poachers (illegal hunters) continue to profit from killing hoolocks in the wild.

Gorilla


Description and biology

The gorilla is considered the most intelligent land animal other than humans. It is the largest of the living primates, an order of mammals that includes lemurs, monkeys, chimpanzees, orangutans, and human beings. When standing on its hind legs, an average male gorilla measures 5 to 5.75 feet (1.5 to 1.75 meters) high.

It can weigh between 300 and 500 pounds (136 and 227 kilograms). Females are smaller, measuring about 5 feet (1.5 meters) in height and weighing between 200 and 250 pounds (91 and 114 kilograms). The color of a gorilla’s coat varies from brown–gray to black.

In males, the hair on the back begins to turn silver after 10 years of age. Males also have a large bone on top of their skull (called the sagittal crest) that supports their massive jaw muscles and gives them their distinctive high forehead. Both sexes have small ears, broad nostrils, and a black, hairless face.

Gorillas are active during the day, foraging for a variety of vines, herbs, leaves, fruit, roots, and bark. During the wet season (April to June), the animals may move as little as 1,500 feet (457 meters) a day in search of food.

During the dry season (July to August), they may travel almost 1 mile (1.6 kilometers). At night, gorillas build individual nests from branches and leaves in trees or on the ground.

Highly social animals, gorillas form groups of 5 to 10 members, although larger groups have been documented. An average group is composed of a dominant mature male (called a silverback) and several females and their young.

When young males in the group become mature (at about age 11), they leave to form their own groups. Young females also leave upon reaching maturity (at about age 8), joining lone males or other groups.

Breeding between males and females can take place any time during the year. After a gestation (pregnancy) period of 250 to 270 days, a female gorilla gives birth to a single infant.

She will carry her infant for the first few months of its life, after which time it will begin to crawl and then walk. The young gorilla will remain dependent on its mother for up to three years. Almost half of all infant gorillas die. Female gorillas successfully raise only two to three young during their lives.

Scientists have recognized three subspecies of gorilla: the western lowland gorilla (Gorilla gorilla gorilla), the eastern lowland gorilla (Gorilla gorilla graueri), and the mountain gorilla (Gorilla gorilla berengei).

Habitat and current distribution

All three gorilla subspecies prefer forest habitats. The western lowland gorilla is found in Nigeria, Cameroon, Central African Republic, Río Muni (the portion of Equatorial Guinea on the African mainland), Gabon, Congo Republic, and Angola. Its population is estimated to be about 35,000. The eastern lowland gorilla, having a population between 3,000 and 5,000, is found primarily in eastern Congo.

The mountain gorilla is found in the Virunga Mountains, a range of volcanic mountains stretching across eastern Congo, southwestern Uganda, and northwestern Rwanda. With a population of about 600, the mountain gorilla is the most endangered of the three gorilla subspecies.

History and conservation measures

Hunting has been the leading threat to gorillas for years. The animals are killed for use as food or trapped for use as pets. Although current international agreements ban the selling or trading of gorillas as pets, illegal capture of the animals continues.

As human populations swell in Africa, increasing numbers of gorillas are hunted for their meat, known as bush meat. A hunter can receive $30 for the remains of a 400–pound (180–kilogram) male gorilla.

Female gorillas are also slaughtered, and their infants are captured and sold to private collectors or zoos. Sometimes hunters make more money for live infant gorillas than for the remains of dead adults.

The destruction of African forests is another serious threat to gorillas. More and more of their habitat has been cleared to create farms and to supply European and Asian timber companies. Logging roads, built deep into the forests, also allow hunters easy access to remaining gorillas.

In 2003, a group of scientists and conservationists called for an upgrade in the status of gorillas from endangered to critically endangered. Data coming from Gabon and the Republic of Congo, where 80 percent of the world’s gorillas live, reveal that the ape population there has decreased by half between 1983 and 2000.

The reasons for the decline were continued hunting and outbreaks among gorillas and chimpanzees of the Ebola virus, a very deadly and contagious virus discovered in Africa in the 1970s that also afflicts human beings.

The group of scientists warn that gorillas are in peril of becoming extinct in the wild. They called for greater enforcement of laws against hunting and capturing gorillas and an increased focus on research of the Ebola virus in primates.

African countries within the gorilla’s range are trying to establish conservation programs for the animal. These efforts, though, are often thwarted by limited finances and social and political unrest.

A successful program has been the Mountain Gorilla Veterinary Project, which provides health care for injured and sick mountain gorillas in Rwanda, Congo, and Uganda. It is one of the few programs in the world to provide treatment to an endangered species in its natural habitat.

Pygmy Hippopotamus


Description and biology

The pygmy hippopotamus is smaller and more piglike in appearance than its larger relative, the common hippopotamus. Its skin color is generally black, with a greenish tinge on the top of its back. Its belly is cream or yellow–gray.

Its eyes are on the side of its round head instead of on top as in the common hippo. An average pygmy hippo has a head and body length of 5 to 5.5 feet (1.5 to 1.7 meters) and a shoulder height of 30 to 39 inches (76 to 99 centimeters).

Its tail extends 6 inches (15 centimeters). It weighs between 355 and 600 pounds (161 and 272 kilograms). By contrast, an average common hippo weighs between 2,425 and 5,720 pounds (1,100 and 2,597 kilograms).

The pygmy hippo is a solitary animal, spending much of its time on the shore near swamps and rivers. It goes in the water only occasionally. Like the common hippo, the pygmy hippo has glands beneath its skin that secrete a pink, sweat–like substance.

This biological fact has inspired the myth that hippos “sweat blood.” This pink substance helps to regulate the hippo’s skin temperature. Because its skin is sensitive to the sun, the pygmy hippo seeks shelter during the day in thickets and other forested areas.

It feeds at night on leaves, shoots, grasses, roots, and fruits. Male and female pygmy hippos usually mate in the water at any time during the year. After a gestation (pregnancy) period of 188 days, a female pygmy hippo gives birth to one calf. She then nurses that calf for eight months.

Habitat and current distribution

Pygmy hippos inhabit lowland forests. They are found in the tropical region of western Africa, primarily in the country of Liberia. Wildlife biologists (people who study living organisms) estimated that the pygmy hippo population in Liberia in the early 1980s was several thousand. No estimates have been made since then, but the population has almost certainly decreased.

History and conservation measures

Deforestation and hunting are the major threats to pygmy hippopotami. Africans hunt the animal and its larger relative for their meat and hides, which are used to make whips and shields. Very few conservation efforts exist for the pygmy hippopotamus. Between 350 and 400 pygmy hippos are held in captivity throughout the world.

Pygmy Hog


Description and biology

The pygmy hog is the smallest of all pig species. An average adult pygmy hog is 25 inches (63.5 centimeters) long, stands 10 inches (25 centimeters) tall at its shoulder, and weighs 19 pounds (8.6 kilograms).

Its short tail measures only 1 inch (2.5 centimeters). Its hide is covered with coarse dark brown or black bristles. Because of its small, bullet–like shape, the animal is extremely agile.

Male pygmy hogs are larger than their female counterparts and have exposed tusks. The normally solitary males interact with the females only during mating season. A female pygmy hog gives birth to a litter of two to six infants, usually in late April or May, after a gestation (pregnancy) period of about 100 days. Both males and females build and use their nests throughout the year.


Habitat and current distribution

Pygmy hogs inhabit dense, tall grasslands. They are found primarily in two wildlife sanctuaries in northwestern Assam (a state in far eastern India): Manas Wildlife Sanctuary and Barnadi Wildlife Sanctuary. Scientists estimate the total number of pygmy hogs to be no more than 300. The actual number may be far less.

History and conservation measures

The pygmy hog is one of the most endangered mammals in the world. Destruction of the animal’s habitat is the main reason. Farmers routinely set fire to grassland forests to clear them for agricultural use. Many pygmy hogs are killed because they cannot escape the extensive fires.

Those that do escape are forced onto very small grassland areas where they are sometimes killed by unexpected fires or onto tea plantations where they are often killed by hunters.

The international wildlife community and the Indian government have focused much attention on the pygmy hog’s plight. In 1985, the International Union for Conservation of Nature and Natural Resources (IUCN) placed the pygmy hog on its first list of the 12 most threatened species in the world.

The Indian government has given the animal the maximum legal protection allowed under its Indian Wild Life Protection Act. In 1986, the United Nations Educational, Scientific, and Cultural Organization (UNESCO) designated the Manas Wild-life Sanctuary as a World Heritage Site.

All these measures have done little to stop the destruction of pygmy hog habitat. If grassland fires in their habitat are allowed to continue unchecked, pygmy hogs will face extinction.

Przewalski’s Horse


Description and biology

Przewalski’s horse is the last truly wild horse. Slightly smaller than most domestic horses, it has a compact body with a thick neck and large head. The color of its upper body is dun (a dull grayish brown), while its belly and muzzle are much lighter.

The horse has a dark stripe along its backbone and a dark, plumed tail. The dark hair on its head and along its neck (the mane) is short and stands erect. Unlike the domestic horse, Przewalski’s horse sheds its mane and the short hairs at the base of its tail annually.

An average Przewalski’s horse may reach 8 feet (2.4 meters) in length and stand 4 to 4.5 feet (1.2 to 1.4 meters) high at its shoulders. It may vary in weight between 440 and 750 pounds (200 and 340 kilograms). The horse feeds primarily on grass and other low vegetation.

Groups of Przewalski’s horses are headed by a dominant stallion (male), which is responsible for breeding with most of the group’s females. The females usually give birth to a single foal (infant) between April and June, after a gestation (pregnancy) period of 330 to 340 days. The foals may nurse for up to two years.

Habitat and current distribution

Przewalski’s horses prefer open grassland, steppe (vast, semiarid grass–covered plain), and semidesert areas. The last possible sighting of Przewalski’s horse in the wild was in 1968.

Chinese biologists (people who study living organisms) believe there may be a small population of horses inhabiting northeastern Xingiang (an autonomous region in northwestern China). It is more likely that this group is extinct.

Over 1,000 Przewalski’s horses are currently held in captivity in zoos and reserves around the world.

History and conservation measures

Przewalski’s horse was discovered in 1878 by Russian geographer and explorer Nikolai Mikhailovich Przhevalsky (1839–1888). Scientists believe the horse once ranged from western Mongolia to northern Xingiang and western Kazakhstan.

By 1900, hunting and competition with domestic horses for food and water greatly reduced the Przewalski’s horse population. By the 1950s, the remaining animals were seen in a small area between southwestern Mongolia and northwestern China called the Takhin–Shara–Nuru (mountain of the yellow horses). The Przewalski’s horse was last seen in the wild in 1968.

The International Union for Conservation of Nature and Natural Resources (IUCN) listed the species as extinct in the wild in 1996. However, the Przewalski’s horse has become a great success story in the ongoing efforts to preserve species through reintroduction to the wild.

In 1992, 16 horses bred in captivity and chosen for their genetic (inherited) traits were slowly and carefully reintroduced to the wilderness at Hustai National Park in Mongolia. By 2000, 84 horses had been reintroduced and 114 foals had been born in the wild.

In the early 2000s, a population of around 142 Przewalski’s horses roamed freely in the park, and the animals appeared to be doing better each year they spend in the wild. They are being very carefully watched and protected as they adapt to the original habitat of the species.

Brown Hyena


Description and biology

The brown hyena, also known as the strand wolf, has a long, brown, shaggy coat with lighter underparts. Its face and legs are gray to black. An average brown hyena measures 43 to 53 inches (109 to 135 centimeters) long and stands 25 to 35 inches (64 to 89 centimeters) high at its shoulder. It weighs between 82 and 104 pounds (37 and 47 kilograms). Males are larger than females.

The brown hyena feeds primarily on the remains of prey killed by other predators. With its strong teeth and jaws, the animal can crush and eat bone. It also feeds on insects, eggs, fruits, and an occasional small animal or bird that it kills. Although it has acute vision and hearing, the brown hyena locates its prey by scent. Lions and spotted hyenas are the animal’s main predators.

Brown hyenas sleep during the day and hunt at dusk or during the night. While on its nightly hunting expedition, a brown hyena will normally cover about 19 square miles (49 square kilometers). Some have been known to travel over 31 square miles (80 square kilometers).

Although often solitary in their habits, brown hyenas will form clans of up to 10 members. Male and female brown hyenas mate at any time during the year. After a gestation (pregnancy) period of 90 to 100 days, a female will give birth to 1 to 5 cubs.

In a communal den (dwelling place shared by all members in a clan), cubs may suckle from females other than their mother. All members of the clan help to feed the cubs by carrying food to the den.


Habitat and current distribution

In southern Africa, brown hyenas inhabit arid (dry) areas such as rocky deserts with thick brush, open grassland and scrub (land covered with stunted trees and shrubs), and semideserts. They sleep in dense vegetation, under sheltering rocks, or in burrows dug by other animals.

History and conservation measures

Scientists do not know the exact number of existing brown hyenas, but they believe the animals’ range and population has been greatly reduced. Of the six African countries where brown hyenas can be found, only Botswana and Zimbabwe host sizable populations.

Many humans dislike brown hyenas because of their foul stench and their cry (which sounds like maniacal laughter). Brown hyenas are often killed by humans for these reasons and because the animals are seen as a threat to livestock. Since brown hyenas feed on carrion (decaying flesh of dead animals), this last view is utterly false.

Brown hyenas are given protection in several conservation areas in the Kalahari, an arid plateau region stretching about 100,000 square miles (259,000 square kilometers) in Botswana, Namibia, and South Africa. The animals are also protected along the coastal regions of the southern Namib Desert in western Namibia.

Jaguar


Description and biology

The jaguar is the largest living member of the cat family in North and South America and the third largest in the world. Its coat ranges from yellow–brown to auburn and is covered with black spots and rosettes, or rings, encircling spots.

An average adult jaguar has a head and body length of 4 to 6 feet (1.2 to 1.8 meters) and a tail length of 18 to 30 inches (46 to 76 centimeters). It stands about 2.5 feet (0.7 meter) high at its shoulder and weighs between 100 and 250 pounds (45 and 115 kilograms). Of the big cats, only the jaguar and the snow leopard do not seem to roar.

Jaguars are good swimmers, runners, and tree climbers. Their diet includes fish, frogs, turtles, small alligators, iguanas, peccaries (mammals related to the pig), monkeys, birds, deer, dogs, and cattle. Jaguars are solitary mammals and are quick to defend their chosen hunting territory.

For male jaguars, this territory ranges between 8 and 80 square miles (20 and 207 square kilometers); for females, it ranges between 4 and 27 square miles (10 and 70 square kilometers).

Male and female jaguars come together only to mate. In tropical areas, mating takes place at any time during the year. In areas with cooler climates, jaguars mate in the spring.

After a gestation (pregnancy) period of 90 to 110 days, a female jaguar gives birth to a litter of one to four cubs. She raises the cubs on her own, and they may stay with her for up to two years.

Habitat and current distribution

Jaguars are found in parts of Mexico, Central America, South America as far south as northern Argentina, and the southwestern United States. Because the animals are secretive and rare, biologists (people who study living organisms) have not been able to determine the exact number remaining in the wild, but in 1998 it was estimated that the jaguar population in the world was less than 50,000 breeding adults. The largest remaining population of jaguars is believed to live in the Amazonian rain forest.

Jaguars live in a variety of habitats, including tropical and subtropical forests, open woodlands, mangroves, swamps, scrub thickets, and savannas.

History and conservation measures

The jaguar once inhabited areas as far north as the southern United States. It is now extinct over much of its former range. The primary reason for the animal’s decline was ruthless hunting, both for sport and for the jaguar’s prized coat. In the early to mid–1960s, spotted cat skins were in great demand. International treaties have all but eliminated the commercial trade of cat pelts.

Jaguars now face the threat of habitat destruction. The clearing of forests to build ranches and farms has rapidly eliminated the animals’ original habitat. Forced to live next to farmland, jaguars are often killed by farmers because they prey on domestic animals.

Small populations of jaguars are protected in large national parks in Bolivia, Brazil, Colombia, Peru, and Venezuela. Smaller reserves and private ranches in these areas provide protection to isolated pairs or families. The jaguar has been bred successfully in zoos.

Matschie’s Tree Kangaroo


Description and biology

Matschie’s tree kangaroo, also known as Huon tree kangaroo, is a marsupial (marsupial young are born undeveloped and are initially carried in a pouch on the outside of their mothers’ body) in the Macropodidae family, which consists of more than fifty kinds of kangaroos. It is one of ten kinds of tree kangaroos, all living in Australia and nearby islands.

The Matschie’s tree kangaroo is usually about 20 to 35 inches (51 to 90 centimeters) long in its head and body; its large tail is 16 to 37 inches (41 to 94 centimeters) long. Females are slightly larger than males, with females weighing about 17 pounds (8 kilograms) and males about 15 pounds (7 kilograms).

Their coats are usually reddish brown or dark brown, but their belly, face, part of their tail, and feet are yellow. Fur on their necks and backs grows in an opposite direction to the rest of their fur, allowing the kangaroo to shed rain when it gets into the right position.

Matschie’s tree kangaroos are arboreal (they live in trees) and nocturnal (they are active mainly at night and sleep during the day). Their bodies are similar to those of other kinds of kangaroos, except they are designed for getting around in trees. Unlike ground kangaroos, their hind limbs are the same length as their front limbs, and the front limbs are big and strong for tree climbing.

They have large feet with pads that keep them from slipping on wet branches, and a long heavy tail that helps them to balance their weight. They have long claws, and their feet can turn sideways in order to grasp branches.

Matschie’s tree kangaroos are capable of jumping long distances—up to 30 or 40 feet—but they generally climb up and down trees slowly and carefully. Their large eyes aid in judging distances when they leap from branch to branch. Their diet consists of leaves and fruit.

Matschie’s tree kangaroos are solitary animals. Each individual lives within its own home range, but a male’s home range may overlap several females’ home ranges. They mate throughout the year. The female gives birth to one offspring after a 35– to 45–day gestation (pregnancy) period.

The “joey,” or newborn infant, unformed and only about an inch long, nurses in the pouch for about 350 days as it develops and then stays with its mother until it is about a year and a half old. The life span of a Matschie’s tree kangaroo is thought to be about 14 years.

Habitat and current distribution

Matschie’s tree kangaroos live in mountainous tropical rain forest areas in the Huon Peninsula in eastern Papua New Guinea and in the island of Umboi and the western tip of New Britain Island, both off Papua New Guinea.

It is estimated that there are about 1,400 animals in the wild. Because Matschie’s tree kangaroos live in inaccessible places, scientific study of the species is difficult and not very advanced.

History and conservation measures

Matschie’s tree kangaroos are hunted by the people of Papua New Guinea for their meat and fur. Hunters in the past used dingos (Australian wild dogs) to locate tree kangaroos by their scent and then to pull them out of the trees.

When guns were introduced in Papua New Guinea, hunters became much more efficient, and the population of Matschie’s tree kangaroos began to decline. At the same time, the species is threatened by the destruction of its habitat in the Huon Peninsula due to logging, mineral and oil exploration, and farming.

Because the Matschie’s tree kangaroo only lives in this one unique area, its chances of survival are very slim unless this habitat is preserved. Papua New Guinea’s traditional communities control the use and management of the nation’s natural resources.

In 1996, the Tree Kangaroo Conservation Program (TKCP) formed to promote the management and protection of tree kangaroos and their habitat while at the same time working to meet the needs of the local people.

Since conservation (protection of the natural world) depends on educating the traditional landowners about the value of biodiversity (the variety of forms of life on Earth) and the need to use sustainable development practices (methods of farming or building communities that do not deplete or damage the natural resources of an area), the program has focused on education.

It has been very successful. By the end of December 2001, 50,000 acres (20,250 hectares) of land had been pledged by local land owners to establish a wildlife management area, and the TKCP expects to increase this area to 150,000 acres (60,725 hectares) in the near future.

Koala


Description and biology

Although the koala is often called a “koala bear” and is noted for its teddy bear looks, it is not a member of the bear family. Rather, it is a marsupial—an animal related to wombats, opossums, and kangaroos. (Marsupials differ from other mammals in that the females carry their undeveloped young in pouches on their abdomen.)

Koalas are small and round, with little eyes and a big black nose. They have no tail. Adults range from about 24 to 35 inches (61 to 90 centimeters) in length and weigh about 10 to 30 pounds (4.5 to 13.5 kilograms). Males are much larger than females.

Koalas have soft, thick gray fur with brown tinges and a white undercoat, with white patches on the chest, neck, and ears. The fur acts as a rain repellant and provides warmth. Koalas living in southern Australia, where winters are colder, have longer fur.

Koalas are arboreal (they live in trees) and nocturnal (active during the night). They have a keen sense of balance and are very muscular, with strong, well–developed limbs for climbing in trees.

Their padded hands and feet are also well adapted to the arboreal life. Their front paws have five fingers with very long claws. Two of the fingers are opposable (capable of being pushed against the other fingers).

The back paws also have long claws and one opposable thumb. Koalas slowly climb up tree trunks and branches by gripping them, first with the front claws, then the back. Often, to go from tree to tree, a koala will descend to the ground, where it is most vulnerable to its predators and to injury.

Koalas are herbivorous, meaning they eat only plants. Their diet consists mainly of eucalyptus (gum tree) leaves. Some types of eucalyptus leaves are poisonous, so koalas are highly selective about which leaves they will eat.

They use their keen sense of smell to select their food. Their digestive systems are adapted to detoxify the poisons and to obtain energy from the eucalyptus leaves, which are low in nutrients. Koalas sleep an average of 18 to 20 hours per day.

They have a very low metabolic rate (method of breaking down nutrients to create energy) and by sleeping long hours and remaining fairly inactive, they are able to save energy. Koalas drink very little water, as the eucalyptus leaves provide them with fluids.

Koalas are territorial animals. Although they are solitary, they live in a complex social world that is evenly distributed throughout eucalypt forests. Each individual animal has its own home range, where it will live its whole life.

The home range must have the right kind of eucalyptus for the koala to eat and it must be located within a stable community of koalas. An individual koala’s territory will usually overlap several other koala territories, and some socializing occurs in the shared areas, though there is little interaction outside of mating season.

Koalas can communicate with each other over large distances by means of a deep bellow. Males bellow, sometimes in place of fighting, to communicate their social and physical position. Females bellow, though far less than males, either to signal aggression or as a part of a mating routine.

Koalas communicate fear, annoyance, and intimacy with other sounds. Also, the male uses scent–marking during mating season, rubbing his large sternal (near the breastbone) gland against tree trunks to communicate his space and dominance.

During mating season, males begin to bellow aggressively. They mate with several females during the season. The female koala gives birth to a single offspring after a gestation (pregnancy) period of 34 to 36 days.

The undeveloped baby, called a “joey,” weighs only a couple of ounces and is delivered directly into the mother’s pouch, where it will stay, constantly nursing, for six to seven months.

When koala young leave the pouch, they stay with their mother, riding on her back, until they are about one year old. For the next two to three years, they will remain in the mother’s home range. After that, they go off to find their own home ranges. Koalas in the wild can live from 13 to 18 years.

Habitat and current distribution

Koalas live in eucalyptus forests ranging from northern Queensland to southern Victoria and southeastern South Australia. However, by most estimates about 80 percent of the eucalyptus forests where koalas have historically lived have now been cleared, and the remaining koalas live in increasingly fragmented areas.

Because the koala is dependent on certain types of eucalyptus leaves for food, the loss of the eucalyptus forests means a decline in the koala population no matter how much they are otherwise protected. According to the Australian Koala Foundation, there are about 40,000–80,000 koalas left in the wild, although there is controversy about these numbers.


History and conservation measures

There were millions of koalas in Australia in 1788, when European settlement began. Although indigenous (native) Australians hunted koalas for food, the koala population remained stable until a market developed in Europe for the thick and soft koala fur.

During the last decades of the nineteenth century and the first decades of the twentieth approximately 3 million koalas were killed for their fur. In 1927, the Australian government banned hunting or intentionally killing a koala without special permission. By that time the population had been reduced from millions to thousands.

Since the 1930s, koalas have been protected from hunters, but their habitat has been swiftly destroyed. The land along the eastern shores of Australia, once teeming with eucalyptus forests, has been cleared for farming; towns and cities have grown up around the farms.

Today, with 80 percent of the eucalyptus forests gone, the remaining 20 percent of the forests in which the surviving koalas live are for the most part privately owned. Koalas have suffered heavily from the destruction of their habitat and from the fragmentation caused by roads, farms, and towns that restrict movement.

This makes it difficult or impossible for the individuals within a koala population to reach one another. Koalas are regularly killed and injured by dogs and by cars. Fires and weed infestations have further ruined the eucalyptus groves that are so important to their survival.

The stresses of living in these fragmented and dangerous conditions have led to large outbreaks of disease among koalas, including infections in their reproductive systems that cause infertility (inability to bear young).

Numerous recovery programs have been initiated in the early 2000s with the mission to stop further clearance of koala habitat areas, to restore and protect certain habitat areas that have been damaged or destroyed, to restrain dogs, to control traffic on roads in koala areas, and to educate area residents on the management of koalas. Research programs on disease, breeding, and genetics are also in place.
 

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