Asio is a genus of typical owls, or true owls, in family Strigidae. The genus Asio contains the eared owls, which are characterised by feather tufts on the head which have the appearance of ears. This group has representatives over most of the planet, and the Short-eared Owl

Short-eared Owl

The Short-eared Owl is a species of typical owl . In Scotland this species of owl is often referred to as a cataface, grass owl or short-horned hootlet. Owls belonging to genus Asio are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or may...

 is one of the most widespread of all bird species, breeding in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, North

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

, Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 and the Galápagos Islands

Galápagos Islands

The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...

. Its geographic range extends to all continents except Antarctica and Australia.

These are medium-sized owls, 30–46 cm (12–18 in) in length with 80–103 cm (31.5–40 in) wingspans. They are long winged and have the characteristic facial disc.

The two northern species are partially migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, moving south in winter from the northern parts of their range, or wandering nomadically in poor vole

Vole

A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...

 years in search of better food supplies. Tropical Asio owls are largely sedentary.

Asio owls are mainly nocturnal, but Short-eared Owls are also crepuscular

Crepuscular

Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...

. Most species nest on the ground, but the Long-eared Owl, Asio otus, nests in the old stick nests of crows, ravens and magpies (family Corvidae

Corvidae

Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English names used are corvids or the crow family , and there are over 120 species...

) and various hawks.

These owls hunt over open fields or grasslands, taking mainly rodent

Rodent

Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s, other small mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s and some bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s.

Species

• Stygian Owl
  Stygian Owl
  The Stygian Owl, Asio stygius is a medium-sized dusky colored owl. It has yellow eyes, a black beak, a dark blackish facial disk, and white eyebrows. Its underparts are a dingy buff color with dark brown barring and streaks...
  
  , Asio stygius
• Long-eared Owl
  Long-eared Owl
  The Long-eared Owl - Asio otus is a species of owl which breeds in Europe, Asia, and North America. This species is a part of the larger grouping of owls known as typical owls, family Strigidae, which contains most species of owl...
  
  , Asio otus
• Abyssinian Owl, Asio abyssinicus
• Madagascar Owl, Asio madagascariensis
• Short-eared Owl
  Short-eared Owl
  The Short-eared Owl is a species of typical owl . In Scotland this species of owl is often referred to as a cataface, grass owl or short-horned hootlet. Owls belonging to genus Asio are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or may...
  
  , Asio flammeus
• Marsh Owl
  Marsh Owl
  The Marsh Owl, Asio capensis, is a species of owl which is a mainly resident breeder in Africa and Madagascar.This species is a part of the larger grouping of owls known as typical owls, Strigidae, which contains most species of owl...
  
  , Asio capensis
• Striped Owl
  Striped Owl
  The Striped Owl is a medium-sized owl with large ear tufts and a brownish-white facial disk rimmed with black. Its beak is black, and it has cinnamon-colored eyes. It has shorter, rounder wings than most of its close relatives. The upperparts are cinnamon with fine black vermiculation and heavy...
  
  , Asio clamator - often placed in Pseudoscops or Rhinoptynx

Two fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 species are recognized nowadays:

• Asio brevipes (Glenns Ferry Late Pliocene of Hagerman, USA)
• Asio priscus (Late Pliocene of Santa Rosa Island, USA)

The supposed Late Eocene/Early Oligocene eared owl "Asio" henrici has been recognized as a member of the fossil barn-owl genus Selenornis. "Asio" pygmaeus (often misspelt pigmaeus) cannot be assigned to a genus without restudy of the material. "Asio" collongensis (Middle Miocene of Vieux-Collonges, France) is now placed in the genus Alasio.(Mlíkovský 2002)