Common Barn Owl, Tyto alba
The Barn Owl falls into a unique owl classification, sharing it in Southern Africa only with the Grass Owl, although, world-wide a few more owls also fall in the classification Tytonidae.
(Barn Owl photo taken by my son)
The Barn Owl has a light coloured or white heart-shaped face with large, dark eyes. It stands about 30 cm tall and from tip to tail, measures up to 45 cm. Weight: 220 – 470 g. Wingspan: up to 98 cm. White breast while from above it has a red-brown body speckled by black-rimmed white spots. Females are slightly larger than males; this can not be discerned in the field, though. The only true way is to discover which bird is sitting on the eggs during the day as the male rarely incubates. Incubating birds should not be disturbed though, as the Barn Owl is said to kill and consume the brood when harassed.
Flight feathers are serrated at their tips, muffling the flapping sound of the wings during flight. Short feathers on side of head form a groove that helps direct sound waves into the ear opening. Sharp talons are extremely efficient at seizing and holding prey. The hooked beak is designed for tearing meat. The eyes in front allow for depth perception and ability to negotiate a heavily obstacled flight path. However, the eyes are fixed in its sockets, so to shift gaze the owl uses its flexible neck to turn its head up to 270 degrees (three quarters of a circle).
Distribution and habitat:
Widely spread, common throughout Southern Africa, Africa and the world, normally near temperate forests or grassy fields where their prey can be found.
Barn Owls are mostly nocturnal. They do not migrate like other birds. They simply drift away from their natal area in random directions at about three months of age. This journey can end anywhere from 20 to 2000 kilometres from the nest. Many die during the first few months of their life from starvation, collision with fences, transport and buildings. Many are killed by other predators. An estimated 3/4 of the young do not make it to become adults and breed. The average lifespan for adults is 18 months. Only one out of 100 birds will survive to 10 years of age. Any Barn Owl reaching 5 years of age is considered old.
The plumage of the owl acts as camouflage while the bird is roosting and nesting. A perched Barn Owl is often overlooked because they blend in with the jumble in a barn. When roosting in trees they are challenging to spot, even in broad daylight. The patterns on their back look like tree bark.
The owl’s most common vocalisation is a territorial call which consists of a screech of about 2 seconds’ duration. Another common call resembles a hair-raising woman's shriek. At the nest site, the young produce a drawn-out hiss that sounds very close to that of a burning gas lamp. Bill-snapping is also heard when the birds are disturbed at the nest. A wide variety of chirps, chips, peeps and snores are made while in the field or at the nest site. Very rarely a Barn Owl will make a quiet hoot. In all, there are 17 different recognised Barn Owl vocalisations, but only about 5 are discernable by most people.
They are carnivorous, hunting primarily in grassland regions for small rodents, although some are known to hunt a variety of prey, including birds, but only when no rodents are present. Each Barn Owl usually consumes 4 to 6 rodents per night, equal to roughly 30 percent of their total body weight. This decreases to about 3 per night for adults feeding young. As a result, the parents loose a lot of weight and become vulnerable while feeding young.
Tytonidae owls use their acute hearing to locate their prey in total darkness. They normally hover silently (their flight feathers are specially developed to allow air to pass through without making sound), low over fields of grass with its head faced down while listening for the movements of rodents below. Each ear is located asymmetrically on the head, allowing the Barn Owl to receive sound signals in its brain at different times. Furthermore, each one of their ears can hear a different range of tones. With this sonar detection system the owl is able to pin-point the exact location of the rodent below, without ever seeing it! When the prey location has initially been determined, the bird drops closer and takes a second reading, then drops upon the prey with its head tilted skyward and its feet spayed very wide. The bird usually lands on the prey with at least one talon touching the prey. Its talons instantaneously trap the prey. If the prey somehow escapes, the bird will sometimes chase it on foot, but usually launches back into the air to relocate it. Although the Barn Owl can see very well in the dark, they rarely use their eyesight in search of prey. Eyesight is used primarily to locate perches and roosting areas.
Each owl will take about 6 rodents every night. If they have young to feed they may take more than 20 per night.
Birds travel 2 to 4 km from the daytime roost site to hunt in roadside ditches, grassy fields, meadows and swampy areas away from buildings. They very rarely hunt rats and mice that live below their roosts! Most hunting is done just after sunset, with a second hunting period about 2 hours before sunrise. When there are young to feed, hunting is constant, all night!
Breeding and nesting:
Barn Owls are cavity nesters, using dark places like tree cavities, caves, pipes or barns. They will often produce two broods per year. The owl lays from 3 to 15 eggs, with up to 7 eggs hatching. Normally, the male takes prey to the female while she incubates the most. The young hatch about 31 days after the egg was laid, and each egg is laid about 2 or 3 days apart. In a large brood of young, the oldest is the largest, and each sibling is accordingly smaller ranking in age. The older siblings often feed the younger ones; this behaviour is unique to Tytonidae owls.
For the first two weeks of age they eat from 2 to 4 rodents per night, per owlet. At three to five weeks of age they will consume 5 to 10 per night, each! The young usually stay at the nest site for several weeks after they learn to fly, which takes about 9 weeks after they hatch. They will continue to consume about 10 rodents per night until they are about ten weeks old, when the parents begin to slow down on the amount of food offered. This encourages the young to leave the nest to search for the parents, drop in weight, and eventually hunt for themselves at about twelve weeks of age. They leave the nest site once this is accomplished.