Birds Belong to the Aves

Birds belong to the Aves Classification in biology and live virtually anywhere in the world. They are amniotes (animals whose eggs are protected from drying out), a group that includes mammals, dinosaurs and reptiles). There are approximately 9,000 species, divided into 24 orders and 146 families (which include, for example, Anseriformes (ducks), apodiformes, caprimulgiformes, charadriiformes, ciconiformes, columbiformes, coraciiformes, cucliformes, falconiformes, galliformes, gaviiformes, and so on). Birds are warm-blooded vertebrate animals that are covered with feathers, have wings, a beak, and no teeth. Feathers are actually modified scales. (Enchanted 1)

There are different types of feathers, depending on that the bird is and what the featheres are used for. There are flight feathers that grow in the wings and tail. There are feathers that cover the rest of the body on the surface that are used for protection against water and other elements. These feathers are often brightly colored in the male birds to attract the female of the species, and duller in females, to camouflage her when she nests. There are feathers that act as thermal insulation; soft, downy feathers that grow close to the skin and keep out the heat or cold.

A bird's body is supported by a skeleton in which many bones are fused together or are absent. Their bones are strong, hollow and light-weight. They have powerful flight muscles.

Birds have a one-way breathing system. Theirs is a unique system in which air follows a one-way route through the respiratory system. This system is unlike our lungs, in which the air backtracks where it came from. Their system of respiration (breathing) is very efficient - much more efficient than our system. Two relatively small lungs where gas exchange occurs, are augmented by bellows-like air sacs (where no gas exchange occurs). These air sacs keep the lungs inflated even when the bird is exhaling. (Enchanted 1)

They also need a strong circulatory system, including a powerful heart in order to circulate the oxygen. A bird's heart beats much faster than our heart does. A hummingbird's heart beats about 1,000 times each minute; a human's heart beats about 60-90 times each minute. (Enchanted 1)

Birds usually eat insects (insectivores), though there are carnivores who eat meat, such as owls and eagles. Some birds are herbivores and eat only plants, such as hummingbirds, grouse and Canadian geese. Others are omnivores and eat plants and meat. Some tropical birds, such as the toucan, eat only fruit (fructivores). They use their keen eyesight to find food and beaks and claws to get, hold and bite their food. The fact that many birds eat insects helps control the bug population and the herbivores help spread seeds to other places, once they eat them. The hummingbird actually helps pollinate flowers. (National Geographic)

Birds live almost everywhere in the world. From the penguins at the South Pole to the Canadian Geese in the far north to the tiny finches and parrots of the jungle to the large and cumbersome Dodo birds in the Pacific, birds have adapted to whatever environment they are found in. Most birds live in an environments that have mild winters and summers, migrating by flying south in the winter to warmer climates and flying north in the summer, to find milder summers. (Sibley 5)

The largest bird is the ostrich of Australia, growing up to 9 feet tall, and the smallest bird is the bee hummingbird, which is only 2 1/2 inches long and weighs 0.06 oz. Hummingbirds can fly backwards and sideways, something that no other bird can do. The ostrich lays the largest eggs, which are up to 4.5 X 7 inches around and weigh 3 pounds. Since the egg is so large, the incubation period for an ostrich egg is 42-50 days, which is more than twice as long as a chicken's egg (20-22 days). (Duncraft 2006)

One of the most unusual birds is the flamingo, which is pink to white in color, has orange eyes, grows to be four feet tall and has the longest tongue of any bird. It lives to be about 50 years old and eats crustaceans, insects and algae. It eats by putting its head under the water, observing everything upside down, and filters organisms from the water with its long tongue.