Birds lose and replace most of their feathers at least once yearly; some species will normally have a partial molt 6 months later. In North America, most species start their major molt around mid-February and end it about a month later. South American parrots usually skip the fall molt but Old World parrots (especially cockatiels) will sometimes drop feathers in early September.
It is important to know if your bird is undergoing normal feather replacement or has feather loss for other reasons.
Types of Feather Damage
Feathers can be chewed off at the level of skin, chewed off with the downy aftershaft left behind, or chewed at just the tips; leaving a moth-eaten appearance. Some birds will extract the feathers completely, oftentimes vocalizing painfully during this process. Other birds simply chew, abnormally preen, or fray their plumage.
Feather damage can also occur from wear and tear, infectious causes, parasites, barbering by cagemates, and cage trauma. Parasites cause feather breakage or rubbing of the plumage and skin, which also breaks the plumage.
Causes of Feather Damage