A group of chickens is called a brood. You can also refer to a group of chickens as a flock, the general term used to describe a group of birds. A group of hens (or female chickens) is called a brood, and a group of baby chicks is called a clutch.
Chickens have combs: the red floppy skin around their head and neck. These combs serve as a cooling system because chickens do not sweat like humans. They also have hollow bones, as do all birds, to make them lighter for flight. Chickens have an interesting medullary bone system that produces calcium for eggshell formation. These specialized bones are located throughout the female's body. When a chicken eats, the bird's quick digestive tract passes the food through the body in only 2.5 hours.
Most chickens have been domesticated and live on farms or in backyards wherever local laws allow. Wild chickens can be found in parts of India and southeast Asia. Chickens that are bred and raised on farms typically spend their time in a fenced area or in chicken coops. They are used as a source of food around the world. Humans consume both the meat and eggs of chickens. More than 70 percent of chicken meat and over 65 percent of chicken eggs are farmed using intensive techniques. Free-range farming is the second most common method. Jungle fowl have appeared in bamboo forests of India and Asia. Some wild or feral chickens are a result of domesticated chickens that were returned to the wild. These birds will often make their way into treetops to avoid predators.
When a rooster and hen mate, a fertilized egg is produced. The chicken lays the egg and, if exposed to the right conditions, it continues to develop for 21 days after which a chick hatches. Hens are born with as many as 4,000 small ova in their ovaries, each of which can develop into a yolk. A rooster mounts a hen to bring their sex organs, both called cloaca, together, and the rooster’s sperm is transferred to the hen where it combines with the ova, resulting in fertilization. When the egg is laid it needs warmth and humidity for a chick to grow; this can be accomplished by the hen sitting on the egg or by artificial incubation. One mating delivers enough sperm to produce as many as five eggs.
Chickens lay eggs and incubate the eggs in a nest. They do not get pregnant. They can lay eggs without mating, but in order for eggs to develop into chicks, they need to mate with a rooster. The mating process is simple and requires only that the birds briefly press their cloacas together in order for the rooster to transfer sperm to the female. Chickens lay one egg every 25 hours. If the eggs are not collected, the hen lays the eggs in a nest and becomes broody. A broody hen stops laying eggs and instead spends most of her time sitting on the eggs, keeping them warm. She turns the eggs several times a day and keeps them at a constant temperature. If the hen mated with a rooster, the eggs hatch after 21 days of incubation. Chickens attempt to brood unfertilized eggs if the eggs are not collected.In many commercial hatcheries, the fertilized eggs are collected and artificially incubated. Collecting the eggs induces the chicken to keep laying more eggs, thus maximizing the productivity of the operation. In an artificial incubation setting, the eggs need to be turned regularly and kept at a constant temperature and humidity until the eggs hatch.
