While chickens live an average of 10 years, most of a hen or rooster's productive life takes place in the first three or four years. Knowing a chicken's approximate age can help you know when to expect eggs and when your chicken is past productive age.
With a Chick-Chick Here
Newly hatched chicks emerge wet and scraggly from the egg. It takes about an hour for chicks to dry once they break free. They should remain in the warmth of the incubator during this time. Once dry, remove them to a brooder to drink water. Chicks younger than a day old seldom pick at their starter mash as they are born with enough nutritional reserves to go one to three days with no ill effects to their health.
By the time chicks are a week old, tiny feathers begin to sprout on their wings. The feathering process will take up to six weeks, with body and head feathers coming in last. The chicks will need supplemental heat until feathering is complete.
Pullets and Cockerels
As the chickens complete feathering at 6 weeks old, sexual differences will begin to emerge. Chicks destined to be roosters may stand up taller than their female nest mates and might even start to crow. Their comb will become larger and redder than female combs. The boys will develop a pronounced bump on the inside of their legs where they will someday grow spurs. Young cockerels grow pointed ends on the feathers adorning their necks, backs and tails. By the time they reach maturity at 16 to 20 weeks old, these feathers become long and iridescent, forming the telltale rooster tail, cape and saddle.
Immature pullets' wing feathers are somewhat pointed on the tips. As a bird grows adult feathers, the wing and tails feathers take on a rounded appearance. You'll also know a hen has not reached laying age by looking at the vent under her tail. If she has never laid an egg, the vent will look like a slit or small circle. When she's able to lay, about 20 weeks of age, her vent will become larger and oval-shaped. You can also feel her pelvic bones between her legs. If they are close together, she's not old enough to lay an egg.
All Grown Up
The age of maturity varies by a few weeks from breed to breed. You'll know a chicken is at least 16 weeks old if they look like an adult. A young rooster at this age will have spurs that are less than a third of an inch long at 6 months old. As he ages, the spur lengthens, and his spurs can be an inch or more in length by the time he's 2 years old.
Chickens of both sexes tend to have small, fine scales on their legs. As leg scales shed each year, rough patches around the toes and joints develop. A chicken with larger, rougher scales is more advanced in age than one with smooth legs.
Hens that are 1 to 2 years old will often lay up to an egg a day. After they reach 2 years old, egg production begins to drop off. By the time a hen reaches 4 or 5 years old, she may lays eggs occasionally. You'll know an older hen by the size of her vent and the eggs she lays -- jumbo-sized eggs typically emerge from a hen who is 3 to 4 years or older. Once a hen stops laying, her pelvic bones will get close together. While you won't be able to tell the exact age of an old hen, you'll know she's past her prime as the colors in her legs, beak and wattles progressively fade with age. A hen near the end of her life will have legs that are pale beige.
Rooster hormones begin to wane about the same age. A rooster begins to crow and mate less frequently with the hens. His sperm quality drops off, leading to less chicks hatching and increased chick mortality. A rooster who is 3 or 4 years old can still handle mating with two or three hens, but a larger flock benefits from a roo in his prime. While you won't be able to tell the exact age of an old rooster, fading color on legs and wattles will let you know he's in his golden years.