Preening is a bird maintenance behaviour that involves using the beak to position feathers, interlock the barbules, clean plumage, and reduce parasites. Feathers contribute to a bird's insulation, waterproofing and flight, so birds spend much time on preening. They may fluff up their feathers to "rezip" the barbules, and use their beaks to gather preen oil from a gland at the base of their tail. They spread the oil by drawing each contour feather through their bills. Ritualised preening has become part of some courtship displays and a displacement activity when birds are subjected to stress. Preening can be a social activity involving two or more birds called "allopreening", which occurs either between a mated pair or flock members in a social species. This may assist in grooming, the recognition of individuals, or reducing conflict. Most allopreening is confined to the head and neck. Ingestion of pollutants or pathogens during preening can lead to health problems. Injury and infection can cause overpreening in caged birds.

Read more: https://en.wikipedia.org/wiki/Preening

_______________________________ Today's selected anniversaries:

1842:

A train derailed and caught fire (depicted) near Versailles, France, killing between 52 and 200 people. https://en.wikipedia.org/wiki/Versailles_rail_accident

1957:

South Vietnamese president Ngô Đình Diệm began a state visit to the United States, his regime's main sponsor. https://en.wikipedia.org/wiki/Ngo_Dinh_Diem_presidential_visit_to_the_United_States

1972:

Four members of Black September hijacked Sabena Flight 571 to demand the release of 315 convicted Palestinian terrorists. https://en.wikipedia.org/wiki/Sabena_Flight_571

1987:

A British Special Air Service unit ambushed a Provisional Irish Republican Army (IRA) unit in Loughgall, Northern Ireland, killing eight IRA members and one civilian. https://en.wikipedia.org/wiki/Loughgall_ambush

_____________________________ Wiktionary's word of the day:

megapolitan: Of or pertaining to a megapolis (“a very large city or urban complex”). https://en.wiktionary.org/wiki/megapolitan

___________________________ Wikiquote quote of the day:

Why should things be easy to understand?   --Thomas Pynchon https://en.wikiquote.org/wiki/Thomas_Pynchon