How do yellow sparrows look at age

If you want to judge the age of the yellow bird, it mainly depends on its feathers and legs. Usually the old bird's feather color is dim, and the skin of the paws is thick.The color of young bird feathers will be brighter, the skin of the paws is very tender, and there are not too many keratin on it.If you want to raise this kind of bird, you must buy smaller. Too old birds are not easy to raise, and it is not convenient to learn, especially before.