Preening

Preening is a grooming behavior most commonly observed in birds, though some other animals engage in similar activities. It involves cleaning, rearranging, and conditioning the plumage, often with the help of a gland located near the base of the tail known as the uropygial or preen gland, which secretes oils that birds spread over their feathers.

During preening, a bird uses its bill to spread oil along feather shafts, aligns barbules, and remove dirt and parasites. The process helps waterproof the plumage, maintain insulation, and reduce feather wear. Preening is commonly followed by bathing or periods of rest, and birds may adjust their grooming pattern depending on weather, activity, and parasite load.

Allopreening, or mutual preening, occurs when individuals groom each other. It is widespread in many social bird species and serves to strengthen bonds, facilitate reconciliation after conflicts, support pair bonding, and help maintain social hierarchies. Allopreening can also reduce aggression and foster cooperative behaviors within groups.

In humans, the term preening can be used more broadly to describe self-grooming or self-presentation—activities such as adjusting clothing, applying cosmetics, or otherwise grooming to influence others’ perceptions. In psychological and sociological contexts, preening-like behaviors may function as signals of status, health, or affiliation.

The prevalence and specifics of preening vary with species, ecological conditions, and social structure. Across birds, it remains a critical maintenance behavior that contributes to feather integrity, waterproofing, and overall fitness.