Saturday, 2 February 2013

Barn Owl


order : Strigiformes      Genus & Species : Tytonidae     Family : Tyto alba

Pale and ghostly, the barn owl patrols silently over fields and grassland at night with slow, effortless wingbeats. It listens for the faintest rustle that betrays its prey. Totally silent in flight and possessing incredibly sharp hearing, the barn owl is an efficient nocturnal hunter, particularly over grassland. They found in open grasslands, wetlands and semi-desert in North and South America, the Caribbean, central and southern Europe, much of Australasia and Africa. 

Habitat : Open, grassy lowlands with a few trees are typical habitat of the barn owl; this adaptable bird is also found in habitat ranging from arid scrub to farmland and roadsides. The barn owl avoids dense woodland, which obstructs its flight, and is rarely found in deserts. It avoids mountains and northern regions where snow lies deep for more than a month or so, because prey can hide beyond reach beneath the snow.The barn owl is therefore absent from most of northern Europe and Asia — from northern Scotland to eastern Russia — and from Canada. The barn owl relies heavily on old buildings for roosting or nest sites; hollow trees, cliffs and caves are also used.The owl’s decline in recent decades can be attributed in part to the alteration of its habitat, as old buildings are pulled down or modernized and woodlands are cleared, although concerned people are helping by erecting nest boxes. 
Food & Hunting : Through the night and for an hour or two before dusk and after dawn, the barn owl hunts by “quartering” the ground: flying slowly back and forth over a hunting patch, a few feet above the ground. It listens for noises that betray prey in the grass below. If it hears a sound, it drops slightly or hovers as it tries to trace it. Then it dives, or even somersaults backward, to attack. As it hits the ground, it may spread its wings to steady itself.The owl eats its catch on the ground or carries it to a perch, such as a nearby fence post. Mice, small voles and shrews are staple prey, but the owl also takes rats, small birds, frogs, toads and even bats. 
Behavior : During the day, the barn owl roosts in a barn, tree hollow or cave. Although it usually hunts in dim light or total darkness, it may occasionally hunt by day, when it relies on the sensitivity of its eyes. Its bone-chilling screams help distinguish it from other owls. Superb hearing is key to its night hunting. Ears are offset on its skull to enhance stereo hearing, and two depressions flanking the bill on its dish-shaped face funnel the faintest sounds (such as a mouse chewing a seed) into the ear openings. By rotating its head, it can obtain an even more accurate fix on the source of a sound. The owl needs a regular supply of food throughout the year. Winter is a particularly hard time — many small mammals are hidden from view. Many owls starve; only a quarter of young birds survive their first winter. Some owls find extra food in winter by catching small birds leaving or returning to their roosts. 
Breeding : Barn owls pair for life. Each spring, the partners perform courtship flights, weaving and chasing over fields to renew their bond. They choose a site in a hole in a building, old tree or cliff, although they don’t build a nest. The female lays her eggs (usually four to seven, but sometimes many more) in a hollow, any time from March to August. She lays each egg at one- to two-day intervals, so up to two weeks may pass between the time that the first and last eggs hatch, about a month later. Pink and naked at first, the female feeds owlets by morsels torn from food brought by the male. Although the young grow rapidly, elder owlets remain the largest; they alone will survive if food is short. They leave in two months and are independent two to three weeks later. 

Face : The heart-shaped facial disc has two concave depressions that help funnel sound to the ears. 
Ears : Ear openings are hidden beneath feathers .The left ear is higher on the head than the right ear, so sounds reach them at different times, helping to pinpoint prey. 
Wings : Broad, rounded wings are typical of most owls, providing powerful lift and great maneuverability. 
Feathers : A fringe along the rear edge of the wing feathers deadens the noise of air rushing through the feathers in flight — a sound that betrays the presence of other hunting birds. 
Feet : The four toes are bare or slightly bristly, with needle sharp talons.The outer toe can be directed backward to hold a branch, and scales on the pads of the foot give a firm grip. 

Weight : 8–16 oz.
Length : 13-17"
Wingspan : 34-37"
Sexual Maturity : 1 years
Breeding Season : Late February or March to November in the Northern Hemisphere 

The barn owl preys mainly on shrews, voles and mice; prey items recorded from around the world include blind moles, gerbils, hamsters, chameleons, crickets and hawk-moths.