What's wrong with the red tail hair?

The red tail hair fell off, indicating that it entered the feather change period.This bird is usually changed in autumn, and the whole process is about 40 days.During the period of hair change, we must do a good job of hygiene, otherwise it is easy to get sick. In addition, a little nutritious feed should be added to promote the development of new feathers.In addition, in addition to changing feathers, they will lose hair, and they will be sick. At this time, the birds often lose their appetite, and the problems can be seen.