Barn owl (Tyto alba) is among the world’s most common owl species and of all the common types of birds. It’s also known as the ordinary barn owl, separating it from the genus Tytonidae.
The barn owl is found almost all over the world except in the wasteland, polar areas, and Asia, to the north of the Himalayas, including Indonesia, to a large extent, and some Pacific Islands.
Phylogenetically, it is evident that in Europe, West Asia, Africa, southeastern Asia, Australasia, America, and a few strongly divergent taxa on islands, there is at least three primary barn owl origin.
Some experts divided the group into western barn owls for the European, Western Asian, and African groups, the eastern barn owls for Southeast Asia and Australasian groups, and the American barn owls for the American groups.
The barn owl is a pale, medium-sized owl, having long wings and a short, square tail. The average specimen’s total length is between 33 – 39 cm (13 – 15 in.), and the maximum range between 29 – 44 cm (11 – 17 in.) across the genus.
Barn owls are about 68 – 105 cm (27 – 41 in.) in typical wingspan. In adult body weight, male owling is also variable, as the Galapagos weight is about 260g (9.2oz) on average, while male East Barn Owl’s (T. javanica) weight is about 555g (19.6oz).
The weights of the Galapagos (T. a. punctatissima) male owls vary. Generally, owls living on small islands are smaller and lightweight, possibly because they are more insect-reliant and need to be maneuverable.
Owls on small islands may have an increased dependency on the body’s presence, and they are more dependent on the insect’s capacity.
Usually, in most subspecies, the birds’ head and top differ from pale brown to grey shades (particularly on the forehead and back).
Some of them are much purer, richer brown, and have all fine black and white speckles, except on remiges and rectrices. Their main wing and tail feathers are light browns with darker bands.
The cardiovascular face is mostly clear and clean but is brown in some sub-groups. On a vertical plane, the left ear is slightly above the eyes, but the right ear is far below the eyes. The orientation of the ear coverings to the face also varies between the ore, with a difference of around 15 degrees.
It has been found that females with more spotting are better than pure birds in continental Europe. In comparison, this does not extend to European males, where the sighting differs by sub-species.
The beak is from pale to dark buff, the plumage’s overall colour, and the iris is blackish brown. The feet vary in colour, like the beak, and range between pink-grey and dark-grey. The feet are black like the beak.
Males tend to have fewer underside spots and are, on average, in one population more colourful than females. The female T.alba are also larger with a weight of over 550g for a major subspecies (19.4oz), while the male owls are usually 10% lighter.
Unlike the common opinion, the barn owl doesn’t hoot (typical owls, such as the tawny owl or other Strix kind members, do this). However, in an eerie, long-drawn-out scream, it creates the signature “Shree” scream that hurts human listening near.
Males in courtship gives out a shrill tweet. The young and old animals make a snake-like hiss for defence when disturbed.
The other sounds produced include a ringing chirrup that denotes placer and a “kee-yak” similar to one of the tawny owl’s vocalizations.
The barn owl casts on its back and blasts with sharps-taloned feet to render an efficient defence when caught or cornered. It can emit rasping sounds or snapping clicks that are probably created by the beak in such situations.
The barn owl is the world’s most common land bird species except in the Antarctic. It covers Europe (except Fennoscandia and Malta), Africaexcept for Sahara, Indian sub-continent, Southeast Asia, South America, Australia, and several Pacific Islands.
The young owls in the British Isles tend to spread mostly along river corridors, and their distance from their homeland is around 9km on average(5.6mi).
The distance travelled in continental Europe is greater, usually between 50-100km, but 1,500km (932mi), with ringed birds from the Netherlands ending in Spain and Ukraine.
The distribution is generally 80km in the United States and 320 km (50-199mi); some 1,760km (1,094mi) is the most visited individuals from the point of origin. Movement from Senegambia to Sierra Leone and up to 576km in South Africa involves 1,000km (621mi).
There is migration in Australia as birds migrate in dry seasons towards the north coast and the west towards the south. There are also nomadic movements as a result of rodent plagues.
Barn owls sometimes show up on Norfolk Island, Lord Howe Island, or New Zealand, demonstrating that the ocean crossing is not beyond their ability.
In 2008, they were first recorded for breeding in New Zealand. The barn owl was successfully introduced to the Hawaiian island of Kauai to control the rodents, but it was found to be feeding on native birds as well.
Behaviour and ecology
Like many owls, the barn owl is nocturnal, depending on its acute sense of hearing while hunting in complete darkness.
It usually becomes active shortly before dusk and can sometimes be seen during the day when relocating from one roosting site to another. It also hunts every day on many Pacific Islands in Britain and maybe elsewhere.
However, in Britain, some birds still hunt every day even when mobbed by birds like magpies, rooks, and black-headed gulls.
This diurnal activity may occur when hunting was difficult because the previous night was wet. The practice may depend on the fact that the owl is mobbed by other birds when it appears during the day.
In comparison, the bird tends to be almost entirely night-life in Southern Europe and the tropics, with a few birds hunt each day being heavily mobbed.
Barn owls are not territorial, but they have a habitat range where they forage. It has a distance of approximately 1km (0.6mi) from the nest site, and it’s an average of about 300 hectares for males in Scotland. The ranges of women’s homes generally match those of their mothers.
Males and females often roost separately outside the breeding season, each with about three preferred sites to dress up during the day and night for a short time.
Roosting sites include holes in trees, cliff cracks, disused houses, fireplaces, and hay sheds, mostly small compared to nesting areas. The birds migrate back to the neighbourhood of the selected nest to roost as the breeding season approaches.
The barn owl is an open-country bird with land, some of which is interspersed with forests at an altitude usually below 2,000m (6,600ft). However, it can be up to 3,000m in the tropics, such as the mountain range of DeguaTembien in Ethiopia. It posses an effortless wavering flight as it crosses the ground, alert to the sounds of potential prey.
Like many owls, the barn owl flies softly, with thin serrations on the front of its feathers and a hairy fringe on the trailing margins. This adds to the airflow break over the wings to eliminate turbulence and the associated noise.
Hairy extensions of its feathers’ barbules provide a soft sensation to the plumage, minimizing the noise created during wing beats.
The owl diet has been studied extensively, and the food eaten can be identified in pellets of indigestible substances, which the bird vomits.
Diet studies have been performed in most parts of the birds’ range, and more than 90 percent of prey are small mammals in humid temperate areas. At the same time, the proportion is more diminutive in hot, dry, and unproductive regions.
Also, a wide range of other creatures is consumed according to the local abundance. Most animals, such as aquatic animals, bats, birds, lizards, and insects are also taken. The Earthworms do not seem to be eaten even when it is abundant.
Voles are the dominant food option in North America and most of Europe, and the shrews are the second most popular food choice. In the Mediterranean, tropics, subtropics, and Australia, mice, as well as, rats are their primary food. Barn owls are typically more specialized feeders in productive areas.
The barn owl flies slowly, quarters the ground, and swings over places that may hide prey. It can also scan its surroundings using branches, fence posts, or other lookouts, and this is a prominent prey position at the oil palm plantations in Malaysia.
The bird has long, broad wings, which make it maneuverable and swift. Its legs and heads are long and slender, enhancing its drilling potential in thick foliages or under the snow.
This allows a massive expansion of the heels when it targets prey. Research has shown that a single barn owl can eat one or two heifers (or equivalents) each night, or around 20 percent of the bird’s body weight. In the roosting areas, surplus food is always hidden and can be used if food is scarce.
The owl in the barn has a fair hearing with asymmetrically positioned paws. Thus, the good location and distance are increased, and the bird doesn’t have to sight to hunt. This method includes the facial disk, as it can be seen that the bird can still find the source in azimuth with the removed ruff feathers but can’t do so in elevation.
This bird can aim its prey when hunting nocturnally or crisply and dive to the ground. It pierces its heels in the form of snow, grass, or brush so that it takes the small creatures with fatal precision.
The barn owl has a high rate of metabolism, which requires comparatively more food than other owls of similar size. Barn owls use more rodents consuming, which are often considered as human pests, than other creatures.
This makes the barn owl one of farm wildlife’s most commercially important species.
Barn owls living in tropical regions can thrive at any time during the year, but individual nesting season is still apparent. Egg-laying typically happens during dry seasons, and the birds tend to prey more on rodents when the vegetation dies down.
In arid areas that include some parts of Australia, breeding can be sporadic and occur in wet periods as a result of transient rises in small mammal populations.
The nesting seasons are more distinct in temperate climates, and there are seasons when there is no laying. The bulk of nesting happens between March and June in Europe as well as North America when the temperature rises.
The actual dates for the laying of eggs differ annually and locally. They are related to the amount of prey-rich foraging habitat in the nest area and the rodent cycle period.
Females are matured enough to breed once they reach the age of 10 – 11 months, while males often wait until next year. Barn owls are typically monogamous, holding onto one partner unless one of the couples dies.
They will roost separately during no breeding season but return to their established nesting site as the breeding season approaches.
They may roost in farm buildings and barns between hay bales in colder climates, harsh environments, and areas where winter food supplies may be scarce. Nonetheless, they are at the risk of some other former nesting species taking over their selected nesting hole.
Some males will set up food zones, spot the hunting zones, often stop and hold on to high eminences where they shout to attract a mate. In a situation where a female loses her partner but retained her breeding grounds, she often appears to be able to attract a new spouse.
The woman spends a lot of time in the nest’s vicinity until she starts laying and fed by the male before the laying of eggs commences.
The male offers a ritual presentation of food when the female has reached peak weight, and copulation takes place on the nest. The females lay eggs, and the size of the average clutch is about five eggs.
The eggs are white, somewhat elliptical, and incubation begins when the first egg is laid. The male continually brings in more provisions while she is sitting on the nest.
The incubation period lasts for about 30 days, hatching is delayed over a long period, and the youngest owl may be several weeks younger than its oldest sibling. A hatching success rate of 75 percent occurs in years with abundant food supplies.
Barn owl exhibits r-selection, which is uncommon for a medium-sized carnivorous mammal. They produce many descendants with a high growth rate, many of which are comparatively less likely to survive in adulthood.
Although wild barn owls are certainly short-lived, this species’ actual life is much higher, and captive individuals can be twenty or more years old.
Nevertheless, wild birds also reach a high age. The US record age of a wild barn owl is 11.5 years, while a Netherlandbird is known to be 17 years, 10 months of age.
Another captive barn owl was more than 25 years old in England. Despite such exceptionally long-lived individuals, the average lifetime for the barn owl is about four years, and 2/3 – 3/4 of every adult lives statistically between 1 – 2 years.
Nonetheless, the mortality is not uniformly spread over the entire lifespan, and only one in three young individuals can survive in their first attempt at breeding.
In temperate areas, the leading cause of death is likely to be hunger, particularly during the fall and winter, when birds begin to develop their hunting skills in the first year.
There is a link in northern and upland areas between old birds’ mortality and adverse weather, heavy snow, and low temperatures. Another cause of mortality is the collision with road vehicles from bird drilling on mown boundaries.
Some of these birds are in bad shape and would have been less able to dodge oncoming vehicles.
In some places, road death rates are exceptionally high as collision rates are influenced by a more increased commercial average annual daily traffic that is grassy, rather than shrubs, and a low abundance of mammals.
The use of pesticides historically caused many deaths, and in some parts of the world, this can still be the case.
Big American opossums (Didelphis), the common raccoon, and related carnivorous rodents, as well as eagles and larger hawks, are predators of the barn owl.
Noted predators include owls such as the great horned owl (Bubo virginianus) in the Americas and the Eurasian eagle-owl (B. bubo).
Despite some reports suggesting that there is no evidence of predation by large horned owls, one Washington study found that barn owls make up 10.9 percent of the local great horned owl diet.
In Africa, Verreaux’s eagle-owls and Cape eagle-owls are the primary predators of barn owls. At the same time, less threatening than the eagle-owls in Europe, the northern goshawk (Accipiter gentilis), and the common buzzard (Buteo buteo) are regular predators.
Also recorded as barn owls, predators were around 12 other large diurnal raptors and owls, ranging from Cooper’s hawk of similar size and scarcely larger tawny owls to massive bald and golden eagles.
In most of their range, barn owls are relatively common and not regarded as globally endangered. The barn owl is the second most largely distributed if viewed as a single global species and broader than the relatively cosmopolitan osprey.
Besides, the barn owl is possibly the most numerous of all raptorial birds, with an IUCN estimate of up to almost 10 million individuals for all barn owls.
Throughout the Americas, the American barn owl species may comprise nearly 2 million alone. However, in the mid-20th century, there was a significant decrease due to organochlorine poisoning (e.g., DDT)