featherless

Featherless is an adjective used to describe organisms or individuals that lack feathers or plumage. In birds, it can refer to temporary conditions during development, such as chicks that have not yet grown full plumage, or to birds that have lost their feathers due to molt.

Feather loss can result from a variety of causes. Natural molts periodically replace old feathers with new ones, during which a bird may appear featherless or sparse in its plumage. Health issues such as parasites (for example, mites), fungal or bacterial infections, nutritional deficiencies, or hormonal imbalances can cause patchy or widespread feather loss. Behavioral factors, including feather plucking or over-preening in captivity, are also common contributors. Environmental stress, poor humidity, or overheating can exacerbate feather loss in some species.

In domestic settings, featherless patches often signal management problems or illness and typically warrant veterinary evaluation. In wild birds, sudden or extensive feather loss can impact thermoregulation, camouflage, and flight, potentially affecting survival unless it is part of a normal molt cycle.

The term featherless is primarily descriptive and not a formal taxonomic category. It is commonly used in observational contexts or discussions of avian biology, health, and evolution, rather than as a systematic classification.

See also: plumage, molt, feather disorder.