The domestic chicken harbours much of the same characteristics of their wild ancestors, the jungle fowl, including sex characteristics. You can often differentiate male from female chickens when they are just young chicks between 3 and 8 weeks old. However, it is easier to sex adult chickens. The main differences between cocks and hens are the same for all breeds of chickens.
Listen to the crow of the chicken. Males will crow loudly, although as chicks, they will sound like weak crows.
Examine the feathers of the chicken. Males have longer neck, back and tail feathers. In some breeds, such as the Phoenix, the tail plumes are quite extravagant.
Look for spurs on the legs of the chicken. The spur looks like an extra toe and toenail located just above the foot on the back of the leg. While some females will have a rudimentary stub for a spur, males have a more obvious and long spur.
Inspect the comb and wattles of the chicken. These are the fleshy parts on the head (comb) and hanging under the head (wattle). The male's are much larger than the female's, although exact size and shapes varies greatly among breeds.