Penguins

Penguins are flightless marine birds that dwell only in the southern hemisphere. They do not inhabit the Arctic, where polar bears live. There are seventeen generally recognized species of penguins. Six species, the Adelie, gentoo, chinstrap, rockhopper, king, and emperor penguins, live in the cold environments of the Antarctic region. The rest live in subantarctic and temperate regions. The macaroni, fiordland, Snares, erectcrested, yellow-eyed, fairy, and royal penguins live off the coasts of New Zealand and Australia and nearby islands. The Magellanic and Humboldt penguins live off the coast of South America. The African penguin lives off the southern coast of Africa, and the GalГЎpagos penguin is native to the GalГЎpagos Islands. Penguins spend much of their lives in the ocean, coming to shore mainly to breed.

Physical Characteristics
All penguins are black with white undersides, and are commonly described as wearing tuxedos. This color pattern acts as camouflage when the penguin is swimming, protecting it from predators. From underneath, the white belly blends with the bright water surface, and fromabove, the black back is indistinguishable from the dark water. Penguin species can be grouped according to common characteristics. Banded penguins have black and white stripe patterns on their chests and heads. The crested penguins all have bright yellow or orange plumes on their heads. Brushtail penguins have long stiff tail feathers. The king and emperor penguins have bright yellow and orange chest and head patches, and the yellow-eyed penguin has a yellow crown. The fairy penguin's feathers are bluish. The emperor penguin is the largest, at nearly four feet tall and seventy-five pounds. The small fairy penguin is sixteen inches tall and about three pounds. All have solid, heavy bones that help them dive deeply into the water. They have streamlined bodies that move smoothly through the water as they pump their strong, flipperlike wings and steer using their webbed feet and tails as rudders. Penguins can hold their breath for many minutes at a time, and they frequently leap out of the water, porpoiselike, to take inmore air. On land, penguins walk with an awkward sideways waddle. Because their short legs are set back on their bodies, they stand erect and must hold out their flippers for balance. Penguins often toboggan themselves by flopping on their bellies and pushing with their flippers and feet. Penguin feathers are tiny and stiff, overlapping to form a waterproof coat. An underneath layer of down helps to trap warm air and protect the penguin from the cold water and wind. Penguins of the Antarctic region have an insulating layer of blubber. Those in temperate climates often have to cool themselves down by ruffling their feathers and holding out their flippers. They can control the flow of blood to their unfeathered areas, such as the feet and under their flippers, which helps regulate their body temperature. Penguins preen their feathers regularly, to spread waterproofing oil from a gland near the tail.

Feeding Behavior and Enemies
Penguins are carnivores. They eat many types of small sea creatures, such as fish, squid, and krill. After locating a school they snatch quickly with their sharp beaks. The tongue and upper palate are covered with stiff spines that grip the slippery food and assist in moving it toward the throat. Penguins make several catches per dive, swallowing the prey whole along with some seawater. Their specialized salt glands above each eye help them drain the extra salt they ingest. Penguins usually enter and exit the water in large groups, to protect themselves from predators who often lurk near the shore. Their main enemies are sea lions, leopard seals, and killer whales. On land, adult penguins are safe. Petrels, skuas, gulls, and sheathbills hunt babies and eggs.

Reproduction
Most penguins follow an annual breeding cycle that begins in the spring, but timing varies according to species and climatic conditions. The GalГЎpagos penguin will breed any month that the water temperature is right, and sometimes twice a year. Emperors begin their cycle in autumn, so there is a good food supply when their chicks hatch in spring. King penguins only reproduce twice every three years, because they follow a fifteen-month cycle. Some penguins nest on the shore and others travel many miles inland to reach their rookeries, and they return to the same ones each year. Penguins are social, and one rookery may have thousands of penguins in closely spaced nests. They often squabble over nesting materials, mates, and territory. Nests are built of grass or stones on the ground, in rock crevices, or in burrows. The male engages in an ecstatic display to attract a female, pointing his beak, flapping his flippers, and squawking. Penguins usually mate for life, and in subsequent years the pair will greet each other affectionately. Two eggs are laid, and the parents take turns incubating for a few weeks at a time while the other leaves to feed. The incubating parent does not eat, and often loses a great deal of weight. Each penguin has a brood patch, an area of bare skin on its lower belly, that allows for better heat transfer to the eggs. Incubation varies fromfive weeks for the small fairy penguin to nine weeks for the emperor. The king and emperor penguins are exceptions to the nesting rule. They lay only one egg, which they cradle on their feet instead of building a nest. They cover it with a flap of skin to keep it warm. Kings take turns incubating, while with emperors, only the male incubates. Chicks are born down-covered, except for emperor chicks, which are naked. The parents brood them while they are young and feed them regurgitated food. When the chicks get too large for brooding, they huddle in crГЁches while the parents leave to hunt for food. When the chicks are grown and go off on their own, the parents molt. They cannot go into the water without their full coats of feathers, so they fast during this two- to four-week period.

Pelican

Pelicans are large water birds that live on seacoasts or inwarminland water habitats. There are seven generally recognized species. The coastal brown pelican lives from North Carolina to the Gulf of Mexico and the Caribbean, and from British Columbia to Chile, as well as the GalГЎpagos Islands. The American white pelican inhabits inland habitats in the western, central, and southeastern United States, Mexico, and Canada. The remaining species live in Australia, Europe, Asia, and Africa.

Physical Characteristics of Pelicans
Pelicans rank among the largest of living birds, ranging in size from four to six feet in length, and weighing from four to sixteen pounds. The brown pelican is smallest, and the large eastern great white pelican has a wingspan of up to ten feet. They have short legs and broad, fully webbed feet, which act as powerful paddles in the water, and cause them to walk with an awkward waddle on land. The pelican is famous for its huge, featherless throat pouch that is attached to the lower mandible. The pouch stretches as it fills with water when the bird is fishing, and can hold nearly three gallons. The pouch also functions as an evaporative cooling mechanism. The pelican opens it mouth and flutters its pouch, which keeps air flowing over the moist surface. Plumage color varies among species and according to age. Pelicans can be predominantly white, black, brown, or gray, with markings on the head, wingtips, underfeathers, or tail. The legs and feet are orange, brown, or black, and the bill and pouch are reddish, orange, or black. During the breeding season, these body parts change color, and many pelicans develop a yellow patch on the chest, a distinctive crest, and a bright ring around the eyes. The American white pelican also grows a noticeable horny knob on its beak.

Feeding and Other Behaviors
Pelicans feed on many species of saltwater and freshwater fish, fromtiny anchovies to fish weighing over a pound. Small crayfish, salamanders, frogs, and snakes are also consumed. The pelican thrusts its head and neck underwater and uses its pouch as a dip net to scoop up its prey. It drains out the water, then tilts its head back and swallows the fish whole. Many pelicans are social fishers, swimming in a circle to close in on the school, then all thrusting and dipping at once. Brown pelicans are solitary feeders, utilizing a spectacular plunge dive from about twenty feet above the water, with neck outstretched and bill pointed down. They hit the water hard, stunning the fish and trapping them in the pouch. Air sacs beneath the pelican's skin cushion its dive and help it to surface quickly. Pelicans are graceful fliers. They take off against the wind, beating their wings and pumping their feet simultaneously, hopping until they are airborne. They fly at a relatively slow speed, with their necks retracted and their heavy bills tucked in and resting on the breast, and often glide on thermals to conserve energy. Pelicans regularly fly in flocks in aV-formation, flapping their wings in unison. They often travel a great distance in search of food. Pelicans sleep standing or sitting on their bellies, with the head twisted back and the beak tucked into its feathers. Self-care activities include muscle exercises such as body shaking, wing flapping, tail wagging, leg stretching, bill throwing, and yawning. Pelicans groom themselves by splash bathing, preening with their beaks, and by rubbing their heads over the body to distribute waterproofing oil to their feathers.

Reproduction
Pelicans are warm weather birds, migrating in large flocks to nest in huge colonies. During courtship, the male uses various behaviors such as bowing, stretching, and pouch displaying to attract a female. Both engage in nesting, the male often gathering sticks and bringing them to the female to incorporate into the nest. Nests are built on the ground or in trees. One to three eggs are laid, and take thirty days to hatch. The chicks are born featherless, and the parents brood them, protecting them from the elements until their feathers come in. Unless the food supply is abundant, only the strongest chick survives. Young chicks eat the parent's regurgitated food. Older chicks feed by sticking their heads in the parent's pouch and throat. By twelve weeks of age, the chicks can fly and begin to hunt for themselves. By one year they have their full plumage. They begin reproduction at three to four years of age.

Endangerment
Pesticides, oil spills, habitat destruction, entanglement in fishing lines, and human disturbance have affected pelican populations in various parts of the world. In 1970, the U.S. Fish and Wildlife Service listed the brown pelican as an endangered species due to the heavy usage of dichlorodiphenyl- trichloroethane (DDT) and endrin.When pelicans ate DDT-contaminated fish, they produced thin-shelled eggs that crushed during incubation. Endrin was toxic. Populations improved after the pesticides were banned, but the birds are still endangered. The spot-billed pelican of Asia and the Dalmatian pelican of Europe and China also face difficulties.

parrot

The hundreds of parrot species are vividcolored members of the bird family Psittacidae. They belong to five classes: macaws, cockatoos, true parrots, parakeets, and lories. In parrot plumage, reds and greens often predominate, but blue, purple, yellow, and black also appear. Parrots inhabitwarmSouth and Central America, southern North America, Africa, Madagascar, Indonesia, and southern and Southeast Asia. They live in lowland tropical or subtropical and mountain forests. Parrot sizes range from threeinch New Guinea pigmy parrots to South American macaws, over three feet long. Macaws, the largest parrots, have long, pointy tails. Cockatoos of Australia and Indonesia are white, with colored crests and other touches of yellow, red, or pink. True parrots are smaller, square-tailed, and have many green feathers. Parakeets, smaller than most true parrots, have long, pointy tails. Lories have red or orange bills, instead of gray bills like true parrots. In most species, males and females look similar, but males are more brightly colored.

Physical Characteristics of Parrots
The most noticeable features of parrots, beyond color, are their down-curved, hooked bills, thick, muscular tongues, and short legs. The bills have strong grasping ability that helps parrots to climb well. Parrot feet are zygodactyl, meaning that the two outer toes of the foot point backward and grip in the opposite direction to the two forwardpointing inner toes. Because of this, parrots walk awkwardly. However, zygodactyly makes them excellent climbers. Parrots eat seeds, fruits, and nuts. Australian lories also eat pollen and nectar. The thick, muscular tongues of most parrots manipulate nuts and seeds, breaking them open as needed. Longer lorie tongues have brushlike tips for eating pollen and nectar. Most parrots find their food in trees, using feet and bills to navigate search areas.

The Lives of Parrots
Parrots are social birds that often live in flocks. Their loud voices are harsh and used in constant communication. Parrot breeding seasons depend on the geographic location of their habitat and the food they eat. Species living outside the tropics, where food supply changes seasonally, have yearly mating seasons. Those in tropical regions breed at irregular intervalswhenfood is available. Most parrots pair for life. Males attract mates by hopping, bowing, wagging tails, and flapping wings. After mating, females lay two to eight small white eggs. Amated pair does not part after breeding. They eat together and groom each other year round. Most parrots nest in holes in trees, termite mounds, and rock or ground tunnels. Others lay eggs in large grass or twig nests. Females incubate eggs for eighteen to thirty-five days, while males supply mates with food. Parrots are born blind and dependent on their parents. Young leave the nest after 1 month in smaller species and after 3.5 months in larger species. Some parrots live for sixty to eighty years.

Some Representative Parrot Species
African gray parrots (Psittacus erithracus) of Central and Western Africa grow to one-foot lengths and one-pound weights. They have gray bodies, black wingtips, and red tail feathers. They eat fruit, seeds, nuts, and berries, nesting in holes in trees. Females lay about four eggs and incubate them for a month, while males feed them. Chicks are fed by both parents. They fly in 2.5 months and parents feed them for 5 more months. These birds form flocks of up to thirty-six individuals. In captivity they live for up to eighty years. Princess parrots (Polytelis alexandrae) live in the scrub land of central and western Australia. They nest in eucalyptus tree holes and eat acacia buds, seeds, berries, and fruit. They are high-altitude fliers, who travel widely seeking food. Their flocks contain up to twenty-four birds. Full-grown, they are fifteen inches long including the tail, and weigh around four ounces. Back, belly, and wing plumage is olive green and yellow; tail feathers are violet; throats are pink; bills are red-orange; and heads are light blue. Breeding occurs between September and December. Females lay four to six eggs and incubate them for three weeks. Young can fly at three months old. An endangered species, they are protected by law. Indonesian salmon-crested cockatoos (Cacatua moluccensis) have plentiful, pink-tinted white plumage. Atop their heads are crests of salmonred feathers, raised to show desire to mate. They eat berries, seeds, nuts, fruits, and insects. Breeding season is in November, and after mating they pair for life. Nests are in tree hollows. Females lay four to seven white eggs. Both birds incubate them for a month. After hatching, young remain in the nest for three months, and then live on their own. Salmon-crested cockatoos live for sixty years in captivity. Wild parrots are pests. For example, farmers see cockatoos as nuisances because they eat crops. An interesting side note is that parrots are very ingenious. This is due to their great intelligence, estimated to equal that of porpoises and primates. Parrots are liked as pets, due to their attractive coloring and ability to learn to talk. The popularity of pet parrots has brought some species close to extinction. In most countries, laws regulate their capture, export, and import. However, the laws are difficult to enforce.

panda

Giant pandas are members of the bear family, and resemble other bears in size and shape. In contrast, the red panda, which lives in the same habitat as the giant panda, is closely related to and resembles the raccoon. The black-and-white giant panda coat is recognizable to people all over the world. Its legs, ears, eye patches, and a band across the shoulders are black, while the rest of the coat is white. Pandas have large jaws and broad teeth, with an increased number of cusps that help them chew tough bamboo stalks. The wide jaw contributes to the large, round shape of the panda's head. The black eye patches create an illusion of very large eyes. These features, along with short legs, give the panda a cute, infantlike appearance to humans, which contributes to their enormous popularity. Another remarkable feature is the "thumb." Pandas have the same five digits of other bears, plus a sixth digit, an opposable thumb, which is actually a modified wrist bone (sesamoid). The thumb allows them to grasp bamboo with considerable dexterity.

Diet and Reproduction
Giant pandas are the most nearly herbivorous of the bears. Ninety-nine percent of their diet consists of bamboo. They also eat other plants and meat that they can scavenge, and will eat a variety of foods in captivity. However, pandas live in areas once covered by vast bamboo forests, and their jaws, teeth, paws, and behavior are all adapted to eating bamboo. Nonetheless, they have a short, simple digestive tract similar to those of other bears, a sign of their carnivorous ancestry, which is not well-adapted to digesting the leaves and fiber of bamboo. Accordingly, pandas can only digest 21 percent of the bamboo that they consume, whereas ruminants such as cows digest up to 60 percent of the plant material that they eat. Because of this inefficiency, pandas consume 12 to 15 percent of their body weight in bamboo each day, and must spend twelve to fourteen hours each day eating. Pandas mate in the spring between March and May, with cubs born in late summer. The total gestational period varies from 87 to 165 days. Cubs are born very small, between three and five ounces. Combined with hormonal data, these characteristics suggest that pandas have a delayed implantation. That is, after fertilization, the embryo remains free-floating in the uterus for several months before attaching to the uterine wall. After attachment, pregnancy is only about forty days, resulting in small newborns. Delayed implantation also occurs in some other bear species. Pandas have between one and three cubs at a time. However, they usually raise only one cub, which the mother nurtures intensively for several months.

Status and Distribution
The giant panda is an endangered species, with fewer than 1,500 individuals remaining. Panda habitat once covered an area of roughly 450,000 square miles in southeastern China, ranging from central China, to Hong Kong, into Burma and Vietnam. Today, they are found within only a 5,400-square-mile area. Even within this area, they are separated into many subpopulations, which prevents interbreeding. Within their range, pandas live at elevations above human settlements (four to eight thousand feet) to the upper edges of bamboo forest(ten to eleven thousand feet). The continuing expansion of human farms and villages has forced them from the lower elevations, which further contributes to the fragmentation of their populations. Small subpopulations are at a high risk for inbreeding, which reduces the genetic variability and individual fitness, placing panda survival in doubt. Because of the giant panda's endangered status and charismatic traits, extensive efforts are being made to prevent its extinction. It is considered a national treasure in China, and killing one is punishable by death. Western conservationists, including the World Wildlife Fund, which uses the panda as its symbol, are also aiding the preservation efforts. Captive panda breeding, mostly in China, has been a focus of these efforts. Unfortunately, breeding programs have never produced enough cubs to introduce into the wild, or even to sustain the captive populations. Still, many scientists and conservationists around the world are working to ensure a future for the giant panda.

Otter

Playful and proud, river otters are born to have fun. At least, it appears that river otters are having fun, because of their playful antics with each other, as well as their facial and body expressions. By any measure, otters are extremely curious and intelligent mammals.

River Otters
Adult river otters reach a length of about 127 centimeters, including their tails, which are nearly one third of that length. Adults weigh between five and fourteen kilograms. Females are slightly smaller than males. River otters have a dense, short fur with great water resistance. Air is trapped beneath their dense furry coats and acts as insulation against the cold water, where these mostly aquatic mammals feed. Otters roll and rub themselves on sand, rocks, old logs, and even snow in their coat grooming activities. These carnivorous mammals mostly feed on fish. Crayfish also serve as diet items when abundant. Researchers have found that river otters feed directly on fish proportionally to their availability and inversely to the fish's swimming ability. Shelters that have been abandoned by other animals are frequently used by river otters, such as old beaver dens or riverbank excavations. On occasion, river otters use rock piles and log jams as dens. Some investigators have discovered nests along river and stream banks which river otters had constructed of aquatic vegetation. Mating activity usually occurs in the water, although there are reports of mating on land. The breeding season is usually late winter to spring. Litter size is between one and six cubs. The newborn otters have full pelage, but their eyes are not open and they have no erupted teeth. Females wean their young at about three months of age. Several predators, including bobcats, foxes, and alligators, have been observed dining on river otters. Humans also have made their impact on otter populations in at least three ways: habitat destruction, water pollution, and overtrapping.

Sea Otters
Another interesting otter is the sea otter. These seafaring mammals are confined to the northern Pacific Ocean. Being the largest in the family Mustelidae, sea otters weigh between twentyseven and thirty-eight kilograms and attain a length of about 148 centimeters. Unlike seals and whales, which have a fat layer (blubber) for insulation, sea otters rely on air trapped beneath their densely packed pelage. Some researchers have estimated the number of hairs in a sea otter's coat to be 800 million. Sea otters, just as their freshwater cousins, have delayed embryo implantation. Females usually produce one pup in a litter. The pup is unable toswimor dive until it is two to three weeks old. Food preferences of sea otters include abalones, sea urchins, clams, and crabs. It is a common practice of sea otters to eat while floating on their backs. Furthermore, sea otters use rocks to open the shells of their diet items, making them a member of a small group of animal tool users. Unlike other members of the Mustelidae, sea otters lack functioning anal scent glands. Also, unlike most carnivores, sea otter teeth are adapted to crushing their prey, rather than tearing.

Ostrich

Ostriches belong to a striking group of flightless birds known as ratites, that also includes emus, cassowaries, rheas, and kiwis. Ratites have flat, smooth breastbones that lack a keel to which flight muscles could attach. They are thus unable to fly, and have weak wing muscles. They do use their wings, spreading them out to help them cool off, and also to splash water when bathing. Ratite feathers are different from those of flying birds. The individual strands are not interlocked, and thus they are soft and billowy and air passes right through them. Their plumes have long been admired by humans and used for decoration and adornment. As with other birds, their feathers function as protection from the elements, and ratites preen, spreading waterproofing oil to their feathers with their beaks. They also molt once a year. Ratites have heavy, strong bones and powerful leg muscles, and are able to run swiftly. They are omnivores, feeding on a variety of grasses, plants, seeds, fruit, insects, and small animals. There are many farms in the United States that raise ostriches, emus, and rheas for their feathers, hide, meat, and oil. In their native countries, ratites are hunted or raised for their feathers and as food. Ostriches have also been tamed for riding and for pulling carts.

Ostrich Characteristics
Ostriches have long necks and legs and are the largest living birds. Males stand eight feet tall, and weigh three hundred pounds. The ostrich can take strides of twenty-five feet and outrun pursuers at speeds of forty miles per hour. If cornered, the ostrich has a powerful kick that can maim an enemy. It has two toes on each foot, and a razor-sharp toenail that both grips the ground while running and can slash the flesh of its enemy. Male ostriches are black with white plumes on their tail and wings. Females are grayish-brown. The head and legs are featherless. The neck is covered with down and is red or grayish. The ostrich has huge eyes with long protective lashes and has keen eyesight for spotting danger a long way off. It can make loud hissing and roaring noises. Ostriches are native to Africa; they are nomadic and graze on open savanna. They often follow herds of zebras or antelope, catching insects and small animals stirred up by their hooves. They swallow sand and stones to help grind up their food. Contrary to popular belief, they require a regular water supply. When mating, male ostriches make a booming call and perform a courtship dance for the females. They are polygamous, taking three or more hens as mates. The male scratches a shallow pit into which each female lays up to a dozen eggs, for a total clutch size of up to thirty eggs. This communal nesting behavior is unusual among birds. The male shares incubation with one dominant female. The male sits at night and the female during the day. Ostriches lay the largest eggs of all living birds, seven inches long and three pounds. The eggshell is very tough and hard for predators to crack open. The parent will sometimes lay with its neck outstretched on the ground when danger threatens, giving rise to the legend that they bury their heads in the sand. They may also feign injury to lure predators away from the nest. Newborn chicks are precocial and instinctively know how to search for food. They are full adults by three years of age.

Ostrich Relatives
Rheas live in flocks on grasslands in South America. They are similar to ostriches in behavior and appearance, although they have three toes on their feet, as do most of the other ratites. They are brownish in color and can be five feet tall. They are polygamous, but only the male incubates the eggs. Emus live on plains in the Australian outback, and flock nomadically according to rainfall patterns and the resulting food supply. The emu is the second largest flightless bird, nearly six feet tall and eightyfive pounds. It has brownfeathers and a loose, moplike tail. Emus are monogamous. Cassowaries live in the rain forests of New Zealand and northeastern Australia. They are solitary and territorial, pairing only to mate. They feed primarily on fruit fallen from trees. Cassowaries have black, loosely hanging feathers, and the wings are composed only of quills. They have bright blue heads and colorful wattles. A distinctive bony crown on the head called a casque helps them push through the dense forest, and is also used to turn over litter in search of food. Kiwis are elusive, nocturnal birds that live in the forests of New Zealand. They are the smallest ratites, about the size of a chicken. They have round, brown-feathered bodies, short legs, four toes, and run by placing one foot directly in front of the other. Their long, slender beaks have nostrils at the very tip, and are used to probe the ground to locate worms, beetles, spiders and larvae by smell. Males have a shrill, whistling mating call. Females lay only one or two eggs that are enormous in proportion to their body size.

Orangutan

The name "orang-utan", commonly written in the hyphenated form, comes from two Malay words: orang meaning "person", and hutan meaning "forest or jungle." Thus, Malaysian orang-utan means "persons of the jungle." Since these animals are very humanlike and live secretive lives in the dense jungle, the origin of the name makes sense. Orangutans are considered to be a threatened species. Less than twenty thousand are believed left in the wild. Orangutans are the second largest of the apes, and show marked sexual dimorphism. Malesmay grow to be 220 pounds (100 kilograms) and females about half that. The arms of a full-grown male may reach a span of 7 to 8 feet (2.1 to 2.4 meters), and their hands are longer than any other primate. These arms and hands are ideally adapted for the arboreal life. Comparatively, the legs are short and weak; there is no external tail. While adult males with arms extended (swinging through the jungle) may appear to be enormous, when standing erect on the ground they rarely exceed 4.5 feet (1.3 meters) in height. Females, by contrast, reach only 3.5 feet (1.1 meters).

Habitat
Two to three million years ago, orangutans lived as far north as China and as far south as Java. As land bridges formed during the Ice Age, orangutans moved south in search of a warmer climate. Today they can only be found on the Indonesian islands of Borneo and Sumatra. Orangutans are the only truly arboreal apes, spending most of their life in forest trees. Their anatomy is well suited for this lifestyle. They walk up trunks using irregularities in the bark to give a grip to fingers and toes, and proceed silently through the middle stories of the forest. These middle stories are especially well suited for horizontal travel, where densely growing trees poke up into the canopy. Often vines are used for quickly moving up and down to get to the next horizontal branches. Orangutans do not jump; they climb and walk the branches on all four legs. They may also sit, recline, or hang in a variety of positions, including suspended from both feet or from one foot and one hand. On the ground, orangutans are normally quadrupedal, although they occasionally walk in the bipedal position. Their weight is borne by clenched fists with the palm touching the ground (unlike gorillas and chimpanzees). Their walk is similar to that of a dog, with diagonally opposed limbs moving forward together. Orangutans live alone, in pairs, or in small family groupings. They build nests in the trees fromgroups of small branches, bent or broken and laid across one another, then lined with smaller branches that are patted down into a circle of approximately three feet in diameter. Nests are placed ten to one hundred feet above the ground and are difficult to spot. Nests may be built new each night when animals are moving about, but may remain intact for several months after being built. While moving and at rest in trees, the orangutan grasps vegetable and animal matter within its reach, testing each one as food. It prefers a variety of jungle fruits as its principal diet, but also eats or chews an infinite variety of buds and leaves, flowers, bark, epiphytes, canes and roots, honey, and even fungi. It forages and eats at leisure, picking fruits with cupped hands and spitting seeds and shells back out of its mouth. Orangutans satisfy most of their need for water by taking it in with their moist food. When on the ground they drink from a stream or lake by bending over from a standing position. They have also been seen to squat down and use their hands to spoon the water into their mouths.

Reproduction and Development
Orangutans reach maturity at about ten years of age, and can begin breeding at any time thereafter. Mating begins with a male singing a song, a low hum that increases to a deep roar before decreasing again. Often playful wrestling, touching, and other acts precede mating. Mating occurs in trees, face to face, usually in a hanging position. Mating may occur repeatedly over a period of several weeks. The pair then separates and each goes its own way. Males play no role in parenting. Female orangutans have a menstrual cycle similar to that of a human female. It lasts twentynine days, with a slight flow of blood for three to four days. Pregnancy lasts nearly nine months, and newborns generally weigh 2.25 to 3.25 pounds (1.1 to 1.6 kilograms). The infant clings to the mother's fur and the mother holds the infant with one arm, usually over the hip. This leaves three limbs for traveling and feeding. The youngster nurses for two to three years, with solid food (chewed up fruit) being added periodically. By the end of the first year the youngster begins to explore away from its mother, but remains within eyesight at all times. By age four, a youngster is pretty much on its own, feeding itself and roaming freely. At that point, the mother is able to mate again. Offspring have only about a 50 to 60 percent survival rate in the jungle, with accidents and disease striking many young orangutans. Orangutans are shy animals that have only one natural enemy: humans. Currently, orangutans are protected by law in all of their territory, but poaching and illegal logging continue to threaten the survival of the species. Unless large areas of undisturbed jungle are set aside as sanctuaries, the orangutan may have a hard time surviving in the future.