An owl hole is a structural entrance built into buildings (such as mills and barns) to allow predatory birds, typically barn owls (Tyto alba), to enter. The birds prey on farm vermin, and therefore benefit the human owner of the structure in a symbiotic relationship.
The barn owl feeds primarily on small vertebrates, particularly rodents. Studies have shown that a barn owl may eat one or more rodents per night; a nesting pair and their young can eat more than 1,000 rodents per year and have been referred to as 'nature's mousetraps'. [1] Locally superabundant rodent species in the weight class of several grams per individual usually make up the single largest proportion of prey. Barn Owls consume more rodents than possibly any other creature. This makes the barn owl one of the most economically valuable wildlife animals to farmers and millers. Farmers and others found these owls effective in keeping down rodent pests, and they encouraged barn owl habitation by providing nest sites. [1] In the few months between hatching and fledging, a clutch of six owlets can consume up to 70 pounds (32 kg) of rodents. [2]
With the advent of modern pesticides the perceived value of biological control has dramatically decreased to the point that few owl holes are still in active use. Many of the holes have been blocked up and landing platforms broken off.
First used at the end of the 17th century, [3] these were often positioned on the gables end of buildings owl holes were usually placed under the eaves. The perch or landing platform was made from stone or wood and usually sloped slightly downward to prevent rain water from entering the building. The entry holes are usually oblong and six to nine inches (152–228 mm) [3] that permits a single bird to enter with space for a safe landing and passage to the interior whilst at the same time excluding larger predators. [1] Owl holes without landing platforms had grooves or rough surfaces beneath the hole to aid grip. On wooden buildings circular examples are sometimes found. [4] The openings usually faced onto open ground so that they could be easily seen by barn owls seeking nesting sites. [1] Owl holes also assisted ventilation within barns and provided for some extra illumination.
Some examples found on the gable ends of wooden barns are very ornate and may be the 'signatures' of the craftsmen who built the barns, coupling this with a practical function of ventilation and as owl holes. Owl holes are sometimes found in association with dovecots as pigeons are not generally a prey species for barn owls.[ citation needed ]
In Scotland owl holes were a common feature of old farms and mills, such as Roughwood Farm and Dalgarven Mill.
Owl holes were found in Wales, a 'triangular' example survives at Llangattock in Glamorgan. [5]
In England an example is to be found on an old pumping mill in Norfolk, old barns in Yorkshire, etc. [6]
In Germany these structures are known as Eulenloch ('owl hole'). [7]
Examples are recorded from Ontario in Canada [5] and the US. [4]
In Hallstatt at the foot of the Echernwand, a trapeze-shaped opening is visible in the rock face. The hole in the cliff has been known as the Eulenloch ('owl hole'). [8]
The common buzzard is a medium-to-large bird of prey which has a large range. A member of the genus Buteo, it is a member of the family Accipitridae. The species lives in most of Europe and extends its breeding range across much of the Palearctic as far as northwestern China, far western Siberia and northwestern Mongolia. Over much of its range, it is a year-round resident. However, buzzards from the colder parts of the Northern Hemisphere as well as those that breed in the eastern part of their range typically migrate south for the northern winter, many journeying as far as South Africa.
Owls are birds from the order Strigiformes, which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers adapted for silent flight. Exceptions include the diurnal northern hawk-owl and the gregarious burrowing owl.
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, being found almost everywhere except for the polar and desert regions, Asia north of the Himalayas, most of Indonesia, and some Pacific Islands. It is also known as the common barn owl, to distinguish it from the other species in its family, Tytonidae, which forms one of the two main lineages of living owls, the other being the typical owls (Strigidae).
The rough-legged buzzard (Europe) or rough-legged hawk (Buteo lagopus) is a medium-large bird of prey. It is found in Arctic and Subarctic regions of North America, Europe, and Russia during the breeding season and migrates south for the winter. It was traditionally also known as the rough-legged falcon in such works as John James Audubon's The Birds of America.
The long-eared owl, also known as the northern long-eared owl or, more informally, as the lesser horned owl or cat owl, is a medium-sized species of owl with an extensive breeding range. The scientific name is from Latin. The genus name Asio is a type of eared owl, and otus also refers to a small, eared owl. The species breeds in many areas through Europe and the Palearctic, as well as in North America. This species is a part of the larger grouping of owls known as typical owls, of the family Strigidae, which contains most extant species of owl.
The northern hawk-owl or northern hawk owl is a medium-sized true owl of the northern latitudes. It is non-migratory and usually stays within its breeding range, though it sometimes irrupts southward. It is one of the few owls that is neither nocturnal nor crepuscular, being active only during the day. This is the only living species in the genus Surnia of the family Strigidae, the "typical" owls. The species is sometimes called simply the hawk owl; however, many species of owls in the genus Ninox are also called "hawk owls".
The great horned owl, also known as the tiger owl, or the hoot owl, is a large owl native to the Americas. It is an extremely adaptable bird with a vast range and is the most widely distributed true owl in the Americas. Its primary diet is rabbits and hares, rats and mice, and voles, although it freely hunts any animal it can overtake, including rodents and other small mammals, larger mid-sized mammals, birds, reptiles, amphibians, and invertebrates. In ornithological study, the great horned owl is often compared to the Eurasian eagle-owl, a closely related species, which despite the latter's notably larger size, occupies the same ecological niche in Eurasia, and the red-tailed hawk, with which it often shares similar habitat, prey, and nesting habits by day, thus is something of a diurnal ecological equivalent. The great horned owl is one of the earliest nesting birds in North America, often laying eggs weeks or even months before other raptorial birds.
The barred owl, also known as the northern barred owl, striped owl or, more informally, hoot owl or eight-hooter owl, is a North American large species of owl. A member of the true owl family, Strigidae, they belong to the genus Strix, which is also the origin of the family's name under Linnaean taxonomy. Barred owls are largely native to eastern North America, but have expanded their range to the west coast of North America where they are considered invasive. Mature forests are their preferred habitat, but they can also acclimate to various gradients of open woodlands. Their diet consists mainly of small mammals, but this species is an opportunistic predator and is known to prey upon other small vertebrates such as birds, reptiles, and amphibians, as well as a variety of invertebrates.
The great grey owl is a very large owl, documented as the world's largest species of owl by length. It is distributed across the Northern Hemisphere, and it is the only species in the genus Strix found in both Eastern and Western Hemispheres. In some areas it is also called Phantom of the North, cinereous owl, spectral owl, Lapland owl, spruce owl, bearded owl, and sooty owl.
The burrowing owl, also called the shoco, is a small, long-legged owl found throughout open landscapes of North and South America. Burrowing owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other open, dry area with low vegetation. They nest and roost in burrows, such as those excavated by prairie dogs. Unlike most owls, burrowing owls are often active during the day, although they tend to avoid the midday heat. Like many other kinds of owls, though, burrowing owls do most of their hunting during dusk and dawn, when they can use their night vision and hearing to their advantage. Living in open grasslands as opposed to forests, the burrowing owl has developed longer legs that enable it to sprint, as well as fly, when hunting.
The eastern screech owl or eastern screech-owl, is a small owl that is relatively common in Eastern North America, from Mexico to Canada. This species is native to most wooded environments of its distribution, and more so than any other owl in its range, has adapted well to manmade development, although it frequently avoids detection due to its strictly nocturnal habits.
The tawny frogmouth is a species of frogmouth native to the Australian mainland and Tasmania and found throughout. It is a big-headed, stocky bird, often mistaken for an owl, due to its nocturnal habits and similar colouring, and sometimes, at least archaically, referred to as mopoke or mopawk, a name also used for the Australian boobook, the call of which is often confused with that of the tawny frogmouth.
The Oriental bay owl is a type of bay owl, usually classified with barn owls. It is completely nocturnal, and can be found throughout Southeast Asia and parts of India. It has several subspecies. It has a heart-shaped face with earlike extensions. The Congo bay owl was formerly classified as a subspecies of Oriental bay owl due to insufficient knowledge, but it has turned out that it might not even belong to the same genus. The Sri Lanka bay owl was also considered a subspecies.
The Tasmanian masked owl is a bird in the barn owl family Tytonidae that is endemic to the island state of Tasmania, Australia. It is the largest subspecies of the Australian masked owl, the largest Tyto owl in the world, and is sometimes considered a full species. The subspecific name castanops, meaning "chestnut-faced", comes from the colouring of the facial disc. It was first described by John Gould, who wrote about it in his Handbook to the Birds of Australia as:
"…a species distinguished from all the other members of its genus by its great size and powerful form. Probably few of the Raptorial birds, with the exception of the Eagles, are more formidable or more sanguinary in disposition."
"Forests of large but thinly scattered trees, skirting plains and open districts, constitute its natural habitat. Strictly nocturnal in its habits, as night approaches it sallies forth from the hollows of the large gum-trees, and flaps slowly and noiselessly over the plains and swamps in search of its prey, which consists of rats and small quadrupeds generally."
A plucking post is a raised structure such as a tree stump which is used regularly by a bird of prey to dismember its prey, removing feathers and various other inedible parts before eating it.
The tawny owl, also called the brown owl, is commonly found in woodlands across Europe to western Siberia, and has seven recognized subspecies. It is a stocky, medium-sized owl, whose underparts are pale with dark streaks, and whose upper body may be either brown or grey. The tawny owl typically makes its nest in a tree hole where it can protect its eggs and young against potential predators. It is non-migratory and highly territorial: as a result, when young birds grow up and leave the parental nest, if they cannot find a vacant territory to claim as their own, they will often starve.
Roughwood once Ruchwood is a farm, originally a estate, possessing at one time a small tower castle. Roughwood is situated near to the town of Beith in North Ayrshire, Scotland; the lands lay within the old Lordship of Giffen.
The eastern barn owl is usually considered a subspecies group and together with the American barn owl group, the western barn owl group, and sometimes the Andaman masked owl make up the barn owl. The cosmopolitan barn owl is recognized by most taxonomic authorities. A few separate them into distinct species, as is done here. The eastern barn owl is native to southeastern Asia and Australasia.
The western barn owl is usually considered a subspecies group and together with the American barn owl group, the eastern barn owl group, and sometimes the Andaman masked owl make up the barn owl. The cosmopolitan barn owl is recognized by most taxonomic authorities. A few separate them
The American barn owl is usually considered a subspecies group and together with the western barn owl group, the eastern barn owl group, and sometimes the Andaman masked owl, make up the barn owl, cosmopolitan in range. The barn owl is recognized by most taxonomic authorities. A few separate them into distinct species, as is done here. The American barn owl is native to North and South America, and has been introduced to Hawaii.
