What is going on with the tail hair of the brother?

The tail hair of the brother may be sick, or malnutrition, or it may be caused by changing hair.If it is sick, in addition to the hair loss, the birds will still be sluggish and poor appetite. This requires timely treatment to recover.If it is malnutrition, as long as some nutritious foods are added, it will soon recover.If you change your hair, you need to clean it well, and you don't have to worry about others.