Preening is a maintenance behaviour found in birds that involves the use of the beak to position feathers, interlock feather barbules that have become separated, clean plumage, and keep ectoparasites in check. Feathers contribute significantly to a bird's insulation, waterproofing and aerodynamic flight, and so are vital to its survival. Because of this, birds spend considerable time each day maintaining their feathers, primarily through preening. Several actions make up preening behaviour. Birds fluff up and shake their feathers, which helps to "rezip" feather barbules that have become unhooked. Using their beaks, they gather preen oil from a gland at the base of their tail and distribute this oil through their feathers. They draw each contour feather through their bill, nibbling it from base to tip. Over time, some elements of preening have evolved to have secondary functions. Ritualised preening has become a part of some courtship displays, for example. It is also a displacement activity that can occur when birds are subjected to two conflicting drives. Though primarily an individual function, preening can be a social activity involving two or more birds – a behaviour known as allopreening. In general, allopreening occurs either between two members of a mated pair or between flock members in a social species. Such behaviour may assist in effective grooming, in the recognition of individuals (mates or potential sexual partners), or in reducing or redirecting potential aggressive tendencies in social species. Most allopreening is confined to the head and neck, smaller efforts being directed towards other parts of the body.
Ingestion of pollutants or disease-causing organisms during preening can lead to problems ranging from liver and kidney damage to pneumonia and disease transmission. Injury and infection can cause overpreening in caged birds, as can confining a bird with a dominant or aggressive cage mate.
Etymology The use of the word preen to mean the tidying of a bird's feathers dates from Late Middle English. It appears to be a variant of the word prune; one now-obsolete definition of prune meant "anoint", based on the Latin ungere, which had the same meaning. This usage was combined with the Scottish and northern English dialect preen meaning "pierce" or "pin", due to the "pricking" action of the bird's beak during preening.
Importance
Preening is a maintenance behaviour used by all birds to care for their feathers. It is an innate behaviour; birds are born knowing the basics, but there is a learned component. Birds that are hand-reared without access to a role model have abnormalities in their preening behaviours. Despite spending considerable time in their efforts, they do not use proper techniques to groom effectively and may do a poor job overall as a result. Displaced feathers can cause birds considerable trouble; such feathers might become damaged, could interrupt the smooth flow of air over a flying bird, or might allow the bird's body heat to escape. Preening allows a bird to reposition such displaced feathers. There is evidence that filoplumes, specialised feathers buried under a bird's outer covering of contour feathers, help to signal when contour feathers have been displaced. Mechanoreceptors at the base of the filoplumes only fire when contour feathers are displaced or the filoplume moves. Preening enables birds to remove dirt and parasites from their plumage, and assists in the waterproofing of feathers. During moult, birds remove the sheaths from around their emerging pin feathers while preening. Because feathers are critical to a bird's survival – contributing to insulation, waterproofing and aerodynamic flight – birds spend a great deal of time maintaining them. When resting, birds may preen at least once an hour. Studies on multiple species have shown that they spend an average of more than 9% of each day on maintenance behaviours, preening occupying over 92% of that time, though this figure can be significantly higher. Studies found that some gull species spent 15% of daylight hours during the breeding season preening, while another showed that common loons spent upwards of 25% of their day preening. In most of the studied species where the bird's sex could be determined in the field, males spent more time preening than females, though this was reversed in ducks. Some ratites, which are not dependent on their feathers for flight, spend far less time on maintenance behaviours. One study of ostriches found that they spent less than 1% of their time engaged in such behaviours.
Preen oil
… excerpt ends here. Continue reading the full article.
