Determining the age of a rooster?

Answer 1

There are only general indicators.

Most breeds get their long tail feathers in at about 15 months old (this is variable)

Spurs show as small nubs until after the first year, fully developed spurs are an indication the bird is older than a year.

The beak can show some calcium build up in older birds while young roosters have a "clean" smooth beak.

Young roosters (also breed specific) have healthy full combs while older birds combs can fade and have that "washed out" color..

Answer 2

There is no way to accurately tell a chickens precise age. You can get a reasonable idea from size, behavior and feather structure. Every breed is different and cross bred chickens are even more difficult to age as they don't conform to the same "rules"

At 20 weeks old most chickens are pretty well full grown. Hens will be close to if not already laying their first eggs. Roosters will have not yet developed their spurs but will be crowing or at least practicing at it and tails will be starting to grow out more so than on the hen. Combs and wattles will be nicely developed but usually not fully. Flight feathers full and glossy not dull. Hens saddles (area on the back near the tail) will not have been worn away yet as they will run from the rooster rather than submit to mounting.

I will provide you with a good link to a site that will show the growth of a chicken through to age 16 weeks.

Answer 3

During the first year it is relatively easy to estimate the age of a cockerel. They start to practice crow at about 4 months old. The begin mating at 8 to 10 months old. Spurs and full tail feathers are usually in by the end of the first year. Thereafter it gets more difficult. All breeds mature at different rates. Roosters often molt at about 18 months old and feathers can lose sheen after the first molt. The feet of an older bird will "washout" and lose color and the bird is usually not as vigorous. Roosters with dull beaks and feet are often older birds.