This problem is related to the details of rural life.

Roosters are usually born in the same year, which means raising roosters in rural areas and slaughtering food for entertaining guests and other important occasions. In addition, the rooster is bigger.

In rural areas, hens usually live for one year, and some live for two or three years. In addition, hens are generally smaller than cocks.

Under the demand of rural areas, the life span of roosters and hens is very different.

So we are used to calling a rooster and an old hen, but there will be no such names as an old hen and a big hen.