What is Bird ?

Everyone recognizes birds. They have feathers, wings, two legs, and a bill. Less uniquely, they have a backbone, are warm-blooded, and lay eggs.

Generally speaking a bird is any member of the class known as Aves that share certain common characteristics and traits. Birds are warm-blooded, bipedal animals whose anatomy is characterized by forelimbs modified through natural selection and evolution to become wings, whose exterior is covered by feathers, and that have, in most cases, hollow bones to assist in flight.

Birds (class Aves) are feathered, winged, bipedal, endothermic (warm-blooded), egg-laying, vertebrate animals. With around 10,000 living species, they are the most speciose class of tetra-pod vertebrates.

Most birds are diurnal, or active during the day, but some are nocturnal, active during the evening hours, such as owls, and still others feed either day or night as needed. Many birds migrate long distances to find the optimum

or ideal habitats, while others rarely range from their original breeding spots. Shared characteristics of birds may include a bony or hard beak with no teeth, the laying of hard-shelled eggs, a light but strong skeleton, and a high rate of metabolism. Most birds are characterized by flight although several well-known species, particularly those that reside on islands, have now lost this ability. Some common flightless birds include the ostrich, penguin, kiwi and now extinct Dodo.

Birds feed on plants, seeds, insects, fish, carrion or other birds. Birds are also an important food source for humans. The most commonly eaten species is the domestic chicken, although geese, pheasants, turkeys and ducks are also common fare, particularly around  Thanksgiving Day and the holidays. Birds grown for human consumption are known as poultry. Humans have caused the disappearance of some species due to habitat destruction, hunting or over consumption.