Feather plucking is a behavioral disorder in birds, which chew, bite or pluck their own feathers with their beak, resulting in damage to the feathers and occasionally the skin.
This habit is related to several factors. One factor can be reproduction. At the time of breeding, birds pull feathers to accommodate their eggs and babies. Reproductive feather plucking is not worrisome, but there are several other causes for this behavior such as:
lack of nutrients
viruses and fungi
hormonal and genetic problems
impaction of the uropygial gland
hypovitaminosis A or B
related to environmental factors
iatrogenic (unknown cause)
Therefore, it is very important if your bird has been presenting this behavior to consult a veterinarian specializing in birds.