Feather loss in pet birds can either be normal or abnormal. Common causes include moulting, infections, feather destructive behaviours or excessive pruning by a cage mate. Birds go through normal moulting once a year although it varies for caged birds due to irregular light hours. When birds are ready to moult, mild stress or fright can cause feather loss. During moulting, good nutrition with vitamins supplement helps your pet bird to re-grow their feathers early.
Furthermore, stress (including emotional stress) in pet birds can result in feather destructive behaviours where the birds pluck out their feathers even when they are not ready to moult. Stress can be in the form of a bully from a cage mate or inappropriate handling by the owner. Stroking your parrot on the back can create a mate bond with the owner. When this is not followed by mating can make the parrot pluck out feathers from the body. It is advisable to identify the source of stress and correct it or remove the bird from such an environment.
Infections from viruses like Circovirus and Polyomavirus are common viral skin infections in birds. Yeasts and Bacteria can cause skin infection resulting in feather loss and a bare patch on the skin. Most feather loss without damage to the hair follicle will re-grow. However, permanent damage to the hair follicles may prevent your bird from re-growing its feathers. It is advisable to have your veterinarian examine your pet birds whenever you notice there is feather loss.