Regarded popularly as nocturnal equivalents of birds of prey, owls have excellent eyesight, fly noiselessly and have nocturnal habits.

They feed mostly on rodents and kill their prey with hooked talons, swallowing the food whole. Bones and fur are later ejected from their bills as pellets.

Owls can be found throughout the world. The order Stigiformes consists of about 134 species of owls, divided into two families: the typical owls(Strigidae) and the barn and bay owls(Tytonidae).

Both families have soft plumage (feathers), the coloration of the plumage varies, but is usually a colour or pattern that helps it blend in with its surroundings by day. Both also have front-facing eyes and short tails.

The females of all owl species are in general larger than the males (as with daytime birds of prey such as hawks and falcons), besides that there are no great differences between the sexes.

The largest owls anywhere belong to the eagle owls (genus Bubo), however there are also fairly small forms among eagle owls.

The two largest species are the eagle owls (Bubo Bubo) and the milky eagle owl, both with a length of about 70 cm and wingspread of 170 cm.

All other eagle owl species are considerably smaller, among them Fraser's eagle owl, the forest eagle owl and the great horned owl.

It prefers hunting in the open country, including cultivated land, and near water. Eagle owls are to be found anywhere from plains to high mountains, provided they can find suitable habitation.

Adult eagle owls are distinctly sedantary birds that remain with their chosen territory. Hence the young roam afar in their first two years, in order to find their own ranges. On such trips they often are electrocuted from flying into high voltage power lines, or are run over on streets or railroad tracks.

Eagle owls' chief prey are mammals, especially mice, rats, squirrels, hedgehogs, and sometimes rabbits.

Eagle owls will also pounce on birds as large as buzzards, crows, magpies, common moorhens and coots, and occassionally a less powerful predator. They launch pursuit of their prey from the perch or in low hunting flight, generally at dusk or dawn.

During the mating season of the European eagle owls, which usually begins in Jan/Feb, the males call especially on calm, very clear evenings and nights.

By imitating the eagle owl call, one can often induce the males to respond. The usual mating grounds are niches in rocks and caves. Eagle owls may also incubate in the abandoned nests of large birds or in depressions on the ground that they have scraped out themselves.

Eagle owls usually mate when they are older than two or three years old, although when under human care, they have been observed to become reproductively capable as early as one year old.

The two or three roundish eggs are incubated about 35 days, if there is not enough food nearby, the unfortunate last one hatched usually perishes or fall victims to its siblings.

At first the young have gray-white down, but soon they change to a brownish-yellow transitional dress which is marked with delicate dark waves trasversely below and at the sides.

As long as they are small, the female broods over them. Later, the mother stands guard at the brood site or nearby. When they are four or five weeks old, the young frequently leave the brood site to climb around the vicinity.

Senses in the Night
Owls have sharp eyesight to detect and locate their prey. The eyes of owls are forward-facing and have a more restricted field of vision than most other birds (whose eyes are at the sides of their heads).

The bird can however rotate its head through almost 360¼. The large eyes and wide surfaces of the lens allow as much light as possible to reach the retina.

The retina is rich in light-sensitive cells (rods) that enable the owl to see well in dim light. But they are poor in other cells called cones, which means an owl's colour vision is weak.

In total darkness, owls are completely blind (!) and hunt using their acute sense of hearing, which is more advanced than in daytime birds of prey. Owls have superb hearing (perhaps the most acute of any bird).

By turning its head and raising the flap of the skin (operculum) at the front edge of each ear hole, it can catch any sounds coming from behind. The ears are located on each side of the head, and receive sounds stereophonically. That means the owl can pinpoint the source of the noise according to which ear detects the noise first.

Owls can detect sounds with frequencies much higher (up to 12 kHz) than humans can detect, thus can hear the very high pitched calls of rodents.

Noiseless Flight
The wings of most owls are large and rounded, the wing area is large with respect to the bird's weight. Thus, owls can fly without a lot of effort, and rarely need to flap their wings.

Owls have a huge number (thousands) of soft flexible feathers, the feathers themselves have edges that appear frayed like a fine comb, these features allow the owl to fly through the air virtually silently.

A likely advantage of silent flight is that it removes backgound noise for the owl so that it can detect the high-frequency sounds of its prey.