A chicken is a type of domestic bird which is often raised as a type of poultry. It is believed to be descended from the wild Indian and south-east Asian Red Jungle fowl.
With a population of more than 24 billion in 2003 (according to the Firefly Encyclopedia of Birds), there are additional chickens in the world than any other bird. They provide two sources of food regularly consumed by humans: their meat, also known as chicken, and eggs.
Male chickens are known as roosters (in the U.S., Canada and Australia), cocks, or cockerels if they are youthful. Castrated roosters are called capons. Female chickens are known as hens, or 'chooks' in Australian English. Young females are known as pullets. Roosters can typically be differentiated from hens by their striking plumage, marked by long flowing tails and bright pointed feathers on their necks.
However, in several breeds, such as the Sebright, the cock only has slightly pointed neck feathers, and the recognition must be made by looking at the comb. Chickens have a fleshy crest on their heads called a comb, and an overweight piece of hanging skin under their beak called a wattle. These organs help to cool the bird by redirecting blood pour to the skin. Both the male and female have characteristic wattles and combs. In males, the combs are often more famous, though this is not the case in all varieties.
When a rooster finds food he may call the additional chickens to eat it first. He does this by clucking in a high pitch as well as picking up and reducing the food. This behavior can also be observed in mother hens, calling their chicks. In some cases the rooster will drag the wing incompatible the hen on the ground, while circling her. This is part of chicken courting ritual. When a hen is used to coming to his "call" the rooster may mount the hen and continue with the fertilization.