The Barn owl is the most widely distributed species of owl in the world and one of the most widespread of all species of birds. It is found almost everywhere in the world except Antarctica. The Barn owl is a medium-sized, pale-colored bird with long wings and a short, squarish tail. Its head and upper body typically vary between pale brown and some shade of grey in most subspecies. Some are purer, richer brown instead, and all have fine black-and-white speckles except on the remiges and rectrices (main wing and tail feathers), which are light brown with darker bands. The heart-shaped face is usually bright white, but in some subspecies it is brown. The left ear is slightly above the eyes on the vertical plane, whereas the right ear is slightly below the eyes. The underparts vary from white to reddish buff among the subspecies, and are either mostly unpatterned or bear a varying number of tiny blackish-brown speckles. The beak varies from pale horn to dark buff, corresponding to the general plumage hue, and the iris is blackish brown. The feet, like the beak, also vary in color, ranging from pink to dark pinkish-grey and the talons are black.
Barn owls occur in all of Europe (except Fennoscandia and Malta), most of Africa apart from the Sahara, the Indian subcontinent, Southeast Asia, Australia, many Pacific Islands, and North, Central, and South America. In general, they are considered to be sedentary, and indeed many individuals remain in chosen locations even when better foraging areas nearby become vacant. Barn owls are birds of open country such as farmland, plantation, shrubland, savanna, or grassland with some interspersed woodland. They prefer to hunt along the edges of woods or in rough grass strips adjoining pasture. For nesting and roosting, they choose holes in trees, fissures in cliffs, disused buildings, chimneys, hay sheds, barns, or silos.
Barn owls are nocturnal birds that rely on their acute sense of hearing when hunting in complete darkness. They often become active shortly before dusk and can sometimes be seen during the day. In Britain, on various Pacific Islands and perhaps elsewhere, they sometimes hunt by day. Barn owl hunt by flying slowly, quartering the ground, and hovering over spots that may conceal prey. They may also use branches, fence posts, or other lookouts to scan their surroundings. Barn owls are not particularly territorial but have a home range inside which they forage. Outside the breeding season, males and females usually roost separately, each one having about three favored sites in which to shelter by day, and which are also visited for short periods during the night. As the breeding season approaches, the birds return to their established nesting site, showing considerable site fidelity. Contrary to popular belief, Barn owls do not hoot. They instead produce the characteristic shree scream, painful to human hearing at close range, in an eerie, long-drawn-out shriek. Males in courtship give a shrill twitter. Both young and old animals produce a snake-like hiss defense when disturbed. Other sounds produced include a purring chirrup denoting pleasure, and a "kee-yak". When captured or cornered, the Barn owl throws itself on its back and flails with sharp-taloned feet, making for an effective defense. In such situations, it may emit rasping sounds or clicking snaps, produced probably by the beak but possibly by the tongue.
Barn owls are usually monogamous, sticking to one partner for life unless one of the pair dies. Once a pair-bond has been formed, the male will make short flights at dusk around the nesting and roosting sites and then longer circuits to establish a home range. When he is later joined by the female, there is much chasing, turning and twisting in flight, and frequent screeches. At later stages of courtship, the male emerges at dusk, climbs high into the sky, and then swoops back to the vicinity of the female at speed. He then sets off to forage. The female meanwhile sits in an eminent position and preens, returning to the nest a minute or two before the male arrives with food for her. The time of breeding varies with location and typically depends upon prey supply. Barn owls are cavity nesters and don't use nesting material; the female incubates the eggs in the dry furry material of which her regurgitated pellets are composed so that by the time the chicks are hatched, they are surrounded by a carpet of shredded pellets. The female lays 2 to 9 chalky white eggs, and the incubation period lasts about 30 days. The female does all the incubation, and she and the young chicks are reliant on the male for food. The chicks are at first covered with greyish-white down and develop rapidly. Within a week they can hold their heads up and shuffle around in the nest. By 3 weeks old the owlets stand, making snoring noises with wings raised and tail stumps waggling, begging for food items. By the 6th week, they are as big as the adults and by the 9th week, the owlets are fully-fledged and start leaving the nest briefly themselves. They are still dependent on their parents until about 13 weeks and receive training from the female in finding, and eventually catching prey. Young females become ready to breed at 10 to 11 months of age although males sometimes wait till the following year.
Barn owls are relatively common throughout most of their range and not considered globally threatened. However, locally severe declines from organochlorine (e.g., DDT) poisoning in the mid 20th century and rodenticides in the late 20th century have affected some populations, particularly in Europe and North America. Intensification of agricultural practices often means that the rough grassland that provides the best foraging habitat is lost. Barn owls also suffer from harsh winters, predation, and road mortality. In some areas, it may be an insufficiency of suitable nesting sites that is another serious factor limiting Barn owl numbers. Nest boxes are popular among conservationists who motivate farmers and landowners to install them for use as natural rodent control.
According to the IUCN Red List, the total population size of the Barn owl is 4,000,000-9,999,999 mature individuals. The European population consists of 111,000-230,000 pairs, which equates to 222,000-460,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
Barn owls are important for the ecosystem they live in as they control populations of prey items and are in turn important food source for local predators. Barn owls consume more rodents - often regarded as pests by humans - than possibly any other creature. This makes them one of the most economically valuable wildlife animals for agriculture. Farmers often find these owls more effective than poison in keeping down rodent pests, and they can even encourage Barn owl habitation by providing nest sites.