Why do ducks eat hair?

Why do ducks eat hair? It is not a disease for ducks to eat hair, but it is sick to eat hair from other ducks.

If you observe carefully, you will find that the duck "eats hair" is to bite the tail first, and then to all parts of the body.

After dissection, scientists found that in the tail of the duck, there is a sebaceous gland, it secretes oil, ducks with a hard mouth with this oil to the whole body, it will play a waterproof role.

When the new duck appears to eat the feathers of other ducks, one is that the duck is morbid and is deficient in calcium and can be supplemented with calcium by feeding fish bone meal or shellfish shells.