Most birds moult, usually before and after breeding, resulting in a breeding or nuptial plumage and a basic plumage. Many ducks and some other species such as the red junglefowl have males wearing a bright nuptial plumage while breeding and a drab eclipse plumage for some months afterwards. The painted bunting's juveniles have two inserted moults in their first autumn, each yielding plumage like an adult females. The first starts a few days after fledging replacing the juvenile plumage with an auxiliary formative plumage; the second a month or so later giving the formative plumage.
Abnormal plumages include a variety of conditions. Albinism, total loss of colour, is rare, but partial loss of colours is more common. Some species are colour polymorphic, having two or more colour variants. A few species have special types of polymorphism, as in the male ruff which has an assortment of different colours around the head and neck in the breeding season only.
Hen feathering is an inherited plumage character in domestic fowl controlled by a single gene. Plumology (or plumage science) is the name for the science that is associated with the study of feathers.
Almost all species of birds moult at least annually, usually after the breeding season, known as the pre-basic moult. This resulting covering of feathers, which will last either until the next breeding season or until the next annual moult, is known as the basic plumage. Many species undertake another moult prior to the breeding season known as the pre-alternate moult, the resulting breeding plumage being known as the alternate plumage or nuptial plumage. The alternate plumage is often brighter than the basic plumage, for the purposes of sexual display, but may also be cryptic to hide incubating birds that might be vulnerable on the nest.
The Humphrey-Parkes terminology requires some attention to detail to name moults and plumages correctly.