What's wrong with the Blau tail hair?

The Blau tail hair was fell because it was changing hair.This kind of bird will change twice a year, once in spring, once in autumn. In addition, it will be changed once after birth. Usually when 40-50 days are large, the fluff on the body will fade, and thenLong feather.During the hair change period, keep the tidy cage and clean the cleaning work. At the same time, it is necessary to supplement some nutritious feeds to promote the growth of new feathers.