Chicken

The Chicken (Gallus gallus domesticus) is a domesticated junglefowl species and the subspecies of the Red junglefowl. Rooster or Cock is a term for an adult male bird, and a younger male may be called a Cockerel. An adult female bird is called a Hen, and a sexually immature female is called a Pullet. 
Humans now keep chickens primarily as a source of food (Meat and Eggs) and as pets.
Chickens are one of the most common and widespread Domestic Animals 
Biology 
Chickens are omnivores. In the wild, they scratch at the soil to search for seeds, insects, and even animals as large as lizards, small snakes, or sometimes young mice. 
Adult chickens have a fleshy crest on their heads called a comb, and hanging flaps of skin either side under their beaks called wattles. Both the adult male and female have wattles and combs. 
Behavior
Chickens are birds and live together in flocks. They incubate eggs and raising of young. 
Vocalizations 
When a rooster finds food he calls other chickens to eat first He does this by clucking in a high pitch as well as picking up and dropping the food. This behaviour may also be observed in mother hens to call their chicks and encourage them to eat.
A rooster's crowing is a loud and sometimes shrill call and sends a signal to other roosters. 
Hens cluck loudly after laying an egg, and also to call their chicks. Chickens also give different warning calls when they see a predator approaching from the air or on the ground.
Crowing 
Roosters almost always start crowing before four months of age. it is possible for a hen to crow as well, crowing is one of the clearest signs of being a rooster
Nesting and laying behaviour 
Hens will try to lay in nests that already contain eggs and have been known to move eggs from nests into their own 
Hatching and early life 
Chicken eggs hatch at the end of the incubation about 21 days. Development of the chick starts only when incubation begins, so all chicks hatch within a day or two of each other, Before hatching, the hen can hear the chicks peeping inside the eggs, and will gently cluck to stimulate them to break out of their shells. The chick begins by pecking a breathing hole with its egg tooth towards the blunt end of the egg, usually on the upper side. The chick then rests for some hours, absorbing the remaining egg yolk and withdrawing the blood supply from the membrane beneath the shell (used earlier for breathing through the shell). The chick then enlarges the hole, gradually turning round as it goes, and eventually severing the blunt end of the shell completely to make a lid. The chick crawls out of the remaining shell, and the wet down dries out in the warmth of the nest.