The Complete List Of Animals

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Bold and curious, barracudas are among the most ferocious fish in tropical waters. The species known as the great barracuda has even been known to attack humans. Barracudas live in the warmer parts of the Atlantic and Pacific oceans, including in the Caribbean Sea.

Physical features
A barracuda has a fierce appearance. Its long mouth has a jutting lower jaw and large, knifelike teeth. Its torpedo-shaped body, built for speed, has small scales and two well-separated fins on the back. Barracudas vary in size, but they average 3 to 4 feet (1 meter) in length. The largest type is the great barracuda, which can reach a length of 8 feet (2 meters).

Behavior
Barracudas are primarily fish eaters. They prey on smaller fish like mullets, anchovies, and grunts. Sometimes they even bite through fishermen's nets to get at the fish inside. Barracudas travel far in search of food. When they find a school of fish, they circle around it until the fish huddle together in fear. Then the barracudas dive into the group while biting and slashing with their teeth. Barracudas will strike at most moving objects, including swimmers.

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The only mammal that flies is the bat. Because of this trait, bats are often mistaken for birds. Bat wings differ from bird wings, however, in that they are covered with skin, not feathers.

Where bats live
About 900 kinds of bats are known, more than any other kind of mammal except rodents. They are found worldwide but are particularly abundant in the tropics. The United States is known to have 40 species of bats. In North America the little brown bat is the most common type.

Bats generally prefer dark places such as caves, hollow trees, or attics. Some bats, however, rest outdoors on trees or rocks. Usually bats are found in groups, or colonies, ranging from a few dozen to hundreds of thousands of individuals.

Physical characteristics
Bats vary greatly in size. The largest of the bats known as flying foxes has a wingspread as wide as 5 feet (1.5 meters). The wingspread of the tiny Kitti's hognose bat, however, is only about 6 inches (15 centimeters).

Bats also display variety in color, fur texture, and facial appearance. The muzzle often resembles that of a rodent or fox. The ears point forward and are usually very large. Bats have fur in shades of gray, tan, brown, or black on the back and in lighter shades on the sides.

Bats have long arms and hands, with especially long fingers. The fingers are joined by a thin membrane that extends from the arms to the tiny legs. This membrane serves as the bat's wings.

Feeding habits
Nearly all bats rest during the day and search for food at night. Most bats eat insects. A brown bat may eat half its weight in insects in one night. In some parts of the southern United States, huge roosts, or shelters, have been erected for bats because the bats are so useful in controlling the insect population.

Some bats have specialized diets. Several species are carnivorous, or meat eating. They feed on a variety of prey, including birds, smaller bats, rodents, and fish. Other bats feed on fruit, pollen, and nectar. The famous vampire bats of South and Central America feed on the blood of mammals and large birds. These bats sometimes serve as carriers of rabies.

Life cycle
Female bats usually bear one young at a time. The pregnancy can last from six or seven weeks to five or six months, depending on the species. Infants are born nude or with light fur. They nurse for five or six weeks or for as long as five months.

Bats have a long life span for animals of their size. Some bats are known to have lived more than 20 years.

Flight and navigation
Bats are well adapted for flying. Most bats cannot walk or run. A bat's legs and feet are only strong enough to hold on when it hangs upside down from a perch, which is how bats rest or sleep. To start flying, a bat drops from its perch. If it is on the ground it usually crawls to some height, using its wing hooks and weak legs, until it can drop into the air. It can, however, take off from a position on the ground if necessary.

Bats can chase insects through thick forests on the darkest night without striking a branch or twig. While flying, most bats send out a continuous cry, so high-pitched that people cannot hear it. These sounds are reflected by obstacles in the bat's path and echo back to the bat's sensitive ears. The animal instantly responds to the signals and avoids the obstacles.

Bears loom large in legends and folk tales. Stuffed bears and fictional bears such as A.A. Milne's Winnie the Pooh continue to delight children. However, bears also call to mind images of fierce creatures. Despite their reputation for ferocity, most bears are mild tempered animals. They become violent only when their food supplies or their young are threatened.

Where bears live
Bears are found in North America, Europe, and Asia. One species lives in South America. However, there are no bears in tropical Africa, a region otherwise well stocked with large mammals.

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The polar bear lives mostly in the Arctic north, where its white fur blends in with snow and ice. Polar bears are often seen on drifting masses of floating sea ice called floes. Brown bears, once widespread in Europe and Asia, are now rare. The grizzly bear, a brown bear of northern and western North America, has been killed off in many areas. The Kodiak bear, an Alaskan island bear closely related to the grizzly, is the world's largest living flesh-eating land mammal.

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The American black bear is smaller than the brown bears. It still ranges widely in the forests of the United States and Canada. There is also an Asian, or Himalayan black bear. Most bears live in cold or temperate climates, but the sloth bear is a creature of the tropics. It lives in India and Sri Lanka. The sun bear, or Malayan sun bear, lives in the forests of Southeast Asia. The spectacled bear, which gets its name from the light-colored rings around its eyes, is the only bear of the Southern Hemisphere. It is found in the Andes Mountains of Chile, Bolivia, Ecuador, and Peru.


Physical characteristics
Bears vary in size according to their species. Generally, their height ranges from 3 to 10 feet (1 to 3 meters). The sun bear is the smallest, at 60 to 143 pounds (27 to 65 kilograms). The Alaskan brown bear known as the Kodiak bear is the largest. It weighs up to 1,720 pounds (780 kilograms). Most bears climb trees with ease and swim well. The polar bear has furry soles to its feet that help it run safely over smooth ice. It also has a membrane between its toes for swimming. Bears have poor eyesight, and most have only moderate hearing. Their sense of smell, however, is extremely keen.

Food habits
Biologists classify bears as carnivores, or meat eaters. The polar bear lives on a diet of walrus, seals, and fish. Other bears eat large quantities of vegetable matter, especially roots, seeds, nuts, and berries, as well as meat. Because they eat both meat and vegetables, bears are sometimes referred to as omnivores, or eaters of everything. Bears will even feed on the carcasses of dead animals where they find them. They also sometimes rummage through garbage dumps, making nuisances of themselves.

Behavior
Bears are solitary creatures that avoid each other except in the mating season. Female bears give birth to one to four cubs at a time, usually in winter. Newborn cubs are small, hairless, and helpless creatures unable to open their eyes for about a week. A newborn grizzly bear weighs as little as 1 pound (0.45 kilogram). Cubs drink their mother's milk for about two months and stay with her until the next breeding period begins, which is usually about a year and a half after their birth. Bears begin to breed at 2 to 6 years of age. The male bear plays no role in raising the cubs. Most bears live from 15 to 30 years in the wild. Captive bears have lived much longer.

During the winter most bears in the wild become inactive for a period of two to six months. In the autumn season the bears eat a great deal and seek out comfortable dens where they can sleep for a long time. This process is similar to hibernation, in which animals sleep through the winter. However, bears are not true hibernators. Their heartbeat rate, body temperature, breathing rate, and blood pressure do not drop significantly lower than normal. And on mild days in midwinter, a bear may come out of its den.

Survival
Tens of thousands of years ago Europeans of the Stone Age hunted the cave bear, a very large species that is now extinct. Bears are still hunted as trophies, or for various assets such as their meat, fur, teeth, and fat. Because of extensive hunting and destruction of their habitat by humans, the brown bear has been almost eliminated from many parts of Europe. In North America the grizzly bear had a reputation for ferocity and was a favorite prey of hunters. During the 19th century grizzlies almost died out in the United States.

Bears are now protected in national parks of many countries, and hunting is carefully regulated. In 1973 conservationists agreed that urgent measures were needed to save the polar bear. As a result, all countries bordering the Arctic Circle now protect the animal. Polar bears cannot be hunted, except by local people using traditional weapons. In the mid-1980s conservationists established programs to protect the grizzly bear population in the western United States.

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The large rodents called beavers are known for using their teeth and paws to build lodges, storehouses, dams, and canals. Beavers are amphibious, which means they are able to live both in water and on land.

Where beavers live
Beavers are native to North America, Europe, and Asia. Today they are found mostly in the northern wooded regions of North America and Europe. Beavers live most of their lives in or near water. They settle along banks of streams, rivers, and lakes bordered by woodland.

Physical features
Beavers are the largest rodents in North America and the second largest in the world after the capybara of South America. An adult beaver may grow to be about 4 feet (1.3 meters) long, including its tail. It may weigh more than 60 pounds (27 kilograms).

A beaver's thick body is covered with a coat of long, reddish-brown outer hairs and soft, dense, brown underfur. This warm, waterproof coat allows the beaver to swim in icy water in the wintertime. Most of a beaver's features—the fur, toes, tail, ears, nose, and lips—allow the animal to live in the water as well as on land. For example, beavers have ears and a nose that are equipped with valves that close when the animal swims underwater. In addition, a beaver's lips close behind its big front teeth so the animal can cut wood and branches underwater. Because of these features, a beaver may remain underwater for up to 15 minutes.

A beaver's front feet are small and look much like a human hand. Beavers use their hands to pick up and carry objects. The tail is scaly, flat, and shaped like a paddle. A beaver uses its tail to warn other beavers of danger by slapping it on the water's surface and making a loud noise.

Behavior
Beavers are nocturnal, which means that they do most of their building and food gathering at night. Beavers eat fresh green bark and the buds, leaves, and twigs of certain trees. In the summer they also eat water plants, berries, swampwood, and fruit.

Beavers are social animals that live and work together. Large groups of beavers build dams in narrow, shallow parts of streams. The beavers begin by gnawing down a number of young trees. They drag these trees to the dam site and bury them in mud. Into this foundation the beavers fit and pile more young trees, adding mud and stones until a strong barrier is completed. Sometimes the beavers build canals to help move logs that are too heavy to drag overland.

The artificial pond created by the dam is where the beavers make their storehouses and permanent homes, or lodges. A lodge is usually the work of a pair of beavers. It is made up of a platform of carefully interlaced branches held together by clay and dead leaves. A dome-shaped roof covers the platform. The lodge may be more than 5 feet (1.5 meters) high. Entrances to the lodge often open underwater. This allows the animals to pass in and out below the winter ice. Another entrance is used for bringing in wood for food. A lodge may be home to as many as eight animals, including an adult pair and two sets of offspring.

Life cycle
Beavers usually mate with the same partner for life. The female is pregnant for about 105 days before giving birth to her young, which are called kits. A litter includes one to nine kits, with four being the most common size. Kits learn to swim when they are only a month old. Beavers may live as long as 19 years.

Beavers and humans
Beavers have been hunted for their fur, their tails, and their musk glands. Musk glands are scent glands at the rear of a beaver's body that produce a liquid used to make perfumes. During the 17th, 18th, and early 19th centuries, beaver skins were an important part of the world's fur trade. In fact, much of the exploration of North America was prompted by the search for beaver fur. Beginning in the 20th century, however, conservation laws were passed to protect beavers throughout the world. As a result, beavers have been saved and resettled in areas where they had once been common.

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For at least 4,000 years honeybees have been kept for their honey and for beeswax, a substance used to make candles, ointments, and many other products. Honeybees and bumblebees are the best-known types of bees, but there are more than 20,000 bee species in all. They live all over the world except in Antarctica. Bees are related to wasps, hornets, and ants.

Structure and form
Most bees have short, thick bodies covered with hair. Like all insects, they have six legs and three body parts: head, thorax, and abdomen. The thorax has three segments. Each segment has a pair of legs; each of the last two segments has a pair of wings attached to it.

When in flight, a bee makes a humming sound because of the rapid movement of its wings. Normally, most bees fly at about 12 12 miles (20 kilometers) per hour, but they can go much faster.

Bees can see color, pattern, and movement with the help of three eyes on top of their heads and two huge, helmetlike compound eyes. Bees see all colors that humans do except red; in addition, bees see ultraviolet, which humans cannot. On the lower part of their heads, bees have biting jaws (mandibles) and a mouth-tongue (proboscis), which they use for sucking and lapping nectar from flowers. The female bee has a device called an ovipositor located at the end of its abdomen. The female bee uses the ovipostor to lay its eggs. It also uses the ovipositor as a weapon to inflict a painful sting. Most bees can sting many times, but a honeybee worker has a tiny, hook-shaped barb that is caught inside the victim. This bee cannot fly away without tearing out its ovipositor and dying. Male bees cannot sting.

Size
The largest bees, which include some of the leafcutter and carpenter varieties, may be up to about 1 12 inches (4 centimeters) long. Bumblebees are larger than most bees—about 1 inch (2.5 centimeters) long. Honeybees range from about 12 to 1 inch (1.3 to 2.5 centimeters), depending on the species. Some of the small leafcutter bees are only 13 inch (1 centimeter) long, and sweat bees are 310 inch (0.7 centimeter) long. The tiniest species, the mosquito bees, may be only 7100 inch (0.2 centimeter) long.

Color
Most bees have black bodies, many with yellow or brown markings. Others have yellow, red, brown, and metallic green or blue bodies, some with brilliant metallic red or purple markings. Honeybees are dark brown with dark yellow stripes. Bumblebees are usually black with wide yellow or orange bands.

Behavior

Nesting
Different species of bees nest in different ways. There are three types of bees based on the way they nest: social bees, solitary bees, and parasitic bees.

Social bees are members of colonies in which they cooperate with others to build the nest and feed and protect the young. They include honeybees, bumblebees, and tropical stingless bees. Social bees are divided into three castes, or classes. Males are called drones. There are two types of females: queens and workers. Both queens and workers lay eggs, but only the queens' are fertilized with the drones' sperm and develop into females. Eggs of the workers develop into males. Queens are not hatched as queens; they become queens when they are fed royal jelly, a substance produced by the salivary glands of the workers.

Most bees are solitary bees. They care only for themselves and their immediate family. Each female makes its own nest and cares for its offspring.

Parasitic bees, or guest bees, do not feed or care for their offspring. They sneak into the nests of other bee species to lay their eggs. They then let the workers of the other nests care for their offspring.

Feeding and pollination
Bees get all of their food from flowers. The food consists of nectar and pollen. Nectar is a sweet liquid produced by the flower's glands. The bees use their long proboscises to drink the nectar. Some bees, especially the honeybee, modify and store their nectar as honey.

Flowers also produce pollen in the form of tiny grains that cling to the bees' bodies. As bees go from one blossom to another, some of the pollen is transferred to the flowers of other plants of the same species. In this way, bees help pollinate, or fertilize, the flowers. This permits the plants to produce their fruits and seeds. The bees' greatest value by far is as pollinators of plants.

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The term beetle refers to thousands of different insects. There are so many beetles that they make up almost 20 percent of all known species of animals in the world.

Where beetles live
Beetles are found all over the world except in Antarctica. Most of the species live on the land. However, some, like the whirligig, water scavenger, and true water beetle, have adapted to live in the water.

Physical features
Like other insects, beetles have three major body segments: the head, thorax, and abdomen. A beetle's head has one pair of antennae and a pair of compound eyes. The thorax has two pairs of wings and three pairs of legs. The abdomen of a beetle has the reproductive organs.

Beetles have antennae, or feelers, to help them find food and recognize other beetles. The body is covered with a hard layer called cuticle that supports the internal organs and protects the body. Beetles have chewing jaws called mandibles.

Beetles are colorful insects ranging from brilliant orange, red, or yellow to iridescent green or blue with a metallic sheen. Some are plain black or have brownish patterns that camouflage them on wood or soil.

Beetles vary in size. Some are only about 1100 inch (0.025 centimeter) long, whereas tropical rhinoceros beetles and goliath beetles may reach lengths of 4 to 6 inches (10 to 15 centimeters). At one time, all beetles were flying insects, but many, like the common ground beetle, have given up flying and move about on their six legs.

Behavior
There are two kinds of beetles, the helpful and the harmful. The helpful kind are valuable because they prey on insect pests and useless garbage that collects in houses, hedges, tree stumps, birds' nests, and similar places. The harmful kinds are those, both adults and larvae, who destroy crops and timber and spread diseases.

Beetles stridulate, or make a high-pitched sound, by rubbing one part of the body against another. This is done by scraping the legs over very fine ridges on another part of the body. When frightened, some of them eject an unpleasant-smelling liquid from the end of their body.

Life cycle
Many beetles produce light and sound to either attract a mate or frighten an enemy. A male beetle, such as a firefly, flashes its light to say that it is ready to mate, and a female returns the signal.

The females lay fertilized eggs. When active larvae called grubs hatch from the eggs, they spend all their time eating. Most grubs eat leaves, flowers, stems, roots, and even the wood of trees. They shed their skin as they grow until they become pupae, when they are soft, pale and inactive. After this stage they emerge as fully grown beetles. The life span of a beetle ranges from a few months in some species to more than four years in others.

From pigeons in big cities to penguins in the remote icy land of Antarctica, all birds have similar characteristics. They all have wings, though they cannot all fly. All birds also have feathers. In fact, that is the one characteristic that makes them unique since birds are the only animals that do have feathers.

Where birds live
Birds are found almost everywhere on Earth, from the Antarctic ice caps to tropical forests. There are more than 9,000 known species of birds.

Many birds migrate long distances between winter and summer homes in search of a constant food supply. For example, after nesting and raising their young, many European birds travel to Africa for the winter.

Physical features

Flight
Birds are able to fly because of their body structure and feathers. A flying bird's body is slender and tapers like a jet airplane. However, not all birds can fly. Penguins spend their time in the water and ostriches have undeveloped wings. Because of this, they must walk or run everywhere. Most birds alternate some walking and swimming with their flying.

Feathers
A bird's feathers protect it from rain, cold, and heat. Water slides off a bird's feathers without soaking through. Birds fluff out their feathers on cold days. These fluffed feathers hold a layer of warm air next to their skin. In hot weather birds flatten their feathers close to their body. This keeps their skin cool by preventing hot air from reaching it. The entire covering of feathers on a bird is called plumage. A bird's feathers wear out and are replaced in a process called molting. All birds molt at least once a year, usually in the summer or early fall. Birds also preen their feathers. Birds preen by using their bill to clean, rearrange, and apply oils to their feathers.

Coloring
In many species of birds the male is more brightly colored than the female. The dull color of the females helps them to remain hidden in their nest. In some cases, the brightly colored male perches a short distance away from the nest. In this way, the male bird draws the attention of enemies to himself and away from the eggs and young.

Metabolism
Like humans, birds are warm-blooded. This means that they have a constant body temperature that is not affected by the temperature of their surroundings. Their hearts beat faster than human hearts, however, and birds breathe more rapidly than humans. Because of this, birds have a high metabolism, meaning that they use up energy very quickly. Therefore, some small birds must eat almost constantly while they are awake.

Senses
Birds have very sharp eyesight. An American kestrel hovering 100 feet (30 meters) above a field can spot a grasshopper and drop directly on it. A thin transparent membrane extends across a bird's eyeball. This membrane keeps the eye moist and protects it from dust. A bird's ears are round openings on either side of the head. In general, birds have a narrower range of hearing than human beings. In most birds the sense of smell is not important for survival.

Size
Birds vary greatly in size. The bee hummingbird of Cuba is generally accepted as the smallest living bird. It is 2 12 inches (6.3 centimeters) long and weighs about 110 ounce (less than 3 grams). The largest living bird is the ostrich. Ostriches can stand 8 feet (2.5 meters) tall and weigh 300 pounds (136 kilograms).

Other features
A bird's bones are hollow and very light. Birds also have a beak and a feature called a crop, which is a pouchlike enlargement of the throat. The crop is used to store food. The gizzard is a part of the stomach where digestive juices break down food. The neck of a bird moves more freely than that of any other animal. A flexible neck allows the bird to look out in all directions for approaching danger. The flexible neck also helps the bird catch food and preen its feathers.

Behavior
Birds communicate with one another by using many different sounds. For example, some baby chicks stop moving when their mother produces a danger call. A male bird will perch somewhere, such as on a telephone wire or tree branch, and sing loudly to inform other males that a certain territory belongs to him. The same song is also used in courtship to attract the female.

Birds keep their feathers clean and smooth. All birds like to bathe. Some even take dry baths in dust, sand, and snow. Such bathing may help get rid of pests in the feathers.

Some birds, such as falcons, live alone. Other birds are more social, such as the guanay cormorants of South America that nest in large groups.

Feeding habits
Many birds are insect-eaters. They have developed special abilities to catch insects. For example, some birds catch insects by probing for them with their long, sticky tongues. Others dig in the ground with their bills. Birds of prey have claws and hooked bills for feeding on larger animals. Herons have spearlike bills for catching fish. Some birds feed on plant material, such as seeds, fruit, or nectar. Many birds eat a wide variety of foods.

Reproduction
Each year, many species of birds return to their summer homes, choose their mates, build their nests, lay eggs, and rear their young. The number of eggs in a set varies from 1 to about 20. Nests may be a scrape in the sand or an elaborately woven hanging structure. A type of bird called the swift uses its saliva to hold together branches when making its nest.

Most birds sit on their eggs to hatch them. This process, called incubation, takes from 11 to 80 days. The length of time that parents care for young birds varies widely. Some young are capable of finding food for themselves almost immediately. Others depend entirely on their parents for food.

Birds and human beings
Humans have interacted with birds in various ways throughout history. In the mythology and literature of many cultures, birds are often featured as characters. Many people enjoy keeping birds as pets, and zoos in many cities import birds from different lands for people to see in person and learn about. Humans have also used birds for their own purposes. For instance, pigeons have long been bred and trained for carrying messages. Birds such as chickens and turkeys are often raised for their meat, and the eggs of certain birds are a source of food for many people.

Birds have also been valued for their feathers, which have been used for decoration since early times. Their use in the headdresses of Native Americans is well known. Ostrich farms have been created to produce the soft and fluffy ostrich feathers that are used to make fans. Large quills were once widely used for writing, and feathers have often been used on arrows.

Humans can have a negative impact on the bird population because of this interest. In the past many birds were killed for their feathers and quills. In addition, bird habitats are destroyed throughout the world when people cut down trees to create farmland, houses, and other buildings. Pollution also destroys bird habitats. When a habitat is destroyed, the birds are forced to look for a new place to live. Many birds do not survive this move, and in some cases, entire species die out.

Birds that pursue other animals for food are called birds of prey. They are also called raptors. Birds of prey are usually fairly large in size. They have good eyesight that helps them see their prey from far away. Their hooked beaks and sharp claws are useful for holding, carrying, and killing prey. Birds of prey can be found all over the world. Some common birds of prey are buzzards, eagles, falcons, hawks, ospreys, owls, and vultures.

Behavior
Most birds of prey hunt by sight during the day. They then sleep at night. Owls, however, hunt at night and sleep during the day.

Birds of prey eat many different kinds of animals. Some eat reptiles such as snakes and frogs. Others eat birds, insects, or rodents. A few birds of prey feast on carrion, which is the flesh of dead animals. Birds that only eat fish, such as penguins, pelicans, and storks, are generally not considered to be birds of prey.

Reproduction
Many birds of prey mate for life. They build nests in trees, on ledges of cliffs, or on the ground. Many lay only one egg at a time, and few lay more than four. Owls are an exception to this rule as they can lay up to 12 eggs at a time. The eggs are usually rounded ovals, white or greenish, and spotted. Occasionally they are completely covered with brown or red-brown pigment. The eggs hatch in the order in which they were laid.

Just after the birds have hatched, they usually receive a lot of attention from their parents. Later, parental attention is steadily reduced until the young are left alone except for brief feeding visits. The young birds make their first flights on their own, without the prodding of their parents.

Relationship to humans
Birds of prey are helpful to humans because they eat dead animals and control rodent populations. However, many of them are facing extinction. In some cases birds of prey are destroyed by humans because the birds are believed to kill small domestic animals. Birds of prey have also been harmed by the effects of human activity on their food sources and habitats. As the human population has grown, more and more trees have been cut down to provide land for farming. This has limited the number of areas where these birds can live. Birds of prey need a large amount of space for their territories so they do not have to compete with other birds for food.

Chemicals used to kill pests have also harmed birds of prey. This happens when the birds of prey eat animals that have earlier eaten plants containing these poisonous chemicals. The poisons in the animals cause the birds of prey to lay eggs with thin shells. These eggs can break before the young hatch. Therefore the birds of prey may have fewer chicks. This problem is made worse because birds of prey lay only a few eggs at one time.

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The so-called American buffalo that used to roam by the millions on the North American plains is actually a bison. The American, or plains, bison is the largest land mammal in North America. The only other species, or type, of bison is the European bison, or wisent. The true buffalo are a different group of animals found in the warm regions of Africa and Asia. Both bison and buffalo belong to the scientific family Bovidae.

Where bison live
At one time, large herds of American bison roamed the area from Mexico to northern Canada and from the eastern United States to west of the Rocky Mountains. Most lived on open prairies. Today, however, the American bison is found mainly in protected areas such as national parks. The European bison used to range over Eastern Europe, but it is now found in restricted areas mostly in Poland and Russia. It lives in woodlands.

Physical features
Bison are large, powerful animals. A fully grown bull, or male bison, stands about 612 feet (2 meters) tall at the shoulder and weighs about 2,000 pounds (900 kilograms). An adult female is about 5 feet (1.5 meters) tall and weighs about 700 pounds (320 kilograms). The European bison is slightly larger than the American bison but is not as heavily built. A bison has a huge head and a hump at the shoulders. Two short horns curve upward. A female's horns are more slender than a male's.

A bison's fur is coarse, shaggy, and dark brown. It grows especially long on the head, neck, and shoulders and usually forms a beard on the chin. The hair on the bison's front is permanent, but the hair on its hind parts is shed each year, beginning in March. By early summer those parts are quite bare. For protection against insect bites, a bison wallows in mud or shallow ponds to cover its body with mud or clay. When the mud or clay dries in the sun, it forms a protective cover. By October new hair has grown on the hind parts. The fur is at its fullest in November and December.

Behavior
Bison prefer to eat grass and herbs, but they also eat twigs and leaves. They move around in small groups, or bands. A band of bison is usually made up of one or more females and several generations of their offspring. Adult males live somewhere outside a band's territory or form their own small groups. The cow, or female bison, usually gives birth to a single calf in May after about nine months of pregnancy. All members of the band protect the young.

Sometimes large herds form when dozens or even hundreds of bands come together. Herds of bison may make short seasonal migrations. They travel a few hundred miles southward in winter and then move back north when warmer weather returns.

Bison usually move with a plodding walk, but they also trot and run. Despite their size, they are agile and fast. They can run at speeds of 40 miles per hour (65 kilometers per hour).

Bison and humans
For the Plains Indians the American bison was the most important game animal. The Indians ate fresh bison meat or preserved the meat by drying and pounding it. Bison hides provided material for tepees and robes.

About 30 to 60 million bison roamed over North America when Europeans arrived in the 16th century. As white settlers moved westward in the 18th and 19th centuries, however, the number of bison dropped dramatically. The settlers killed millions of the animals for food, for hides, or just for sport. By the 1880s fewer than 1,000 American bison were left, most of them in Canada.

At the start of the 20th century, as the American bison neared extinction, cattlemen and conservationists came together to protect the remaining animals on government land. In the early 21st century there were as many as 200,000 American bison, and they were no longer in danger of extinction.

The European bison also came close to extinction. For centuries the animals have been protected on government lands in Poland. Today European bison are kept and bred in other countries as well. Some animals have been released into the wild. Their numbers remain low, however.

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There are many types of blackbirds—small birds whose name comes from the black color of the males' feathers. The best-known type is the red-winged blackbird. Other kinds of blackbirds include the Old World blackbird, the yellow-headed blackbird, and the grackles. Although crows and ravens also have black feathers, they do not belong to the blackbird family.

Where blackbirds live
Blackbirds make their nests in marshes, on dry prairies, or in dense evergreen forests. The Old World blackbird lives in woods and gardens throughout the warmer areas of Europe and Asia as well as in New Zealand and Australia. Most blackbirds, however, are found in North America. Red-winged blackbirds live in cattail marshes from Canada to the West Indies and Central America. The yellow-headed blackbird of the Western plains also nests in marshes. Grackles are found along the southern coasts of the Atlantic Ocean and the Gulf of Mexico.

Physical features
Blackbirds generally range from 8 to 16 inches (20 to 41 centimeters) in length. Red-winged blackbirds are about 8 inches (20 centimeters) long. Old World blackbirds are about 10 inches (25 centimeters) long. At about 16 inches (41 centimeters) and with a long tail, the male great-tailed grackle is the largest of the blackbirds.

Though the males are mostly black, blackbirds boast a variety of colored details. The male red-winged blackbird has yellow and red feathers on its shoulders. The female is brown and resembles a large sparrow. Male Old World blackbirds are all black, and the females are brown. Both have an orange bill and orange coloring around the eyes. The male yellow-headed blackbird has a bright yellow head and a black body; the female has a dull yellow head and gray-brown body. The male great-tailed grackle has black feathers with a purple or blue-green shine.

Behavior
Many blackbirds make loud squeaks and gurgling clucks while fluttering their wings, bobbing their bodies, and wagging their tails. Red-winged blackbirds chirp musical songs.

Most blackbirds eat insects. Blackbirds are a benefit to humans because they eat harmful insects such as crop-eating pests.

Blackbirds have a variety of nesting habits. Some build nests on the ground, others attach theirs to marsh plants, and some build them high above the ground in trees. Some blackbirds, including the tricolored blackbird and the common grackle, build their nests in colonies. Both the male and the female usually help feed the young.