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 is one of the most widespread of all bird species, breeding in Europe, Asia, North and South America, the Caribbean, Hawaii and the Galápagos Islands. Its geographic range extends to all continents except Antarctica and Australia.
These are medium-sized owls, 30-46 cm in length with 80-103 cm wingspans. They are long winged and have the characteristic facial disc.
The two northern species are partially migratory, moving south in winter from the northern parts of their range, or wandering nomadically in poor vole 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. 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) and various hawks.
Two fossil species are recognized nowadays:
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)
Density, diet and productivity of Long-eared Owls Asio otus in the Italian Alps: the importance of Microtus voles
Nov 01, 2008; Capsule Relatively large populations, feeding predominantly upon voles, were present at higher elevations. Aims To determine the...
Habitat preferences for Long-eared Owls Asio otus and Little Owls Athene noctua in semi-arid environments at three spatial scales
Jul 01, 2004; Capsule There is a relationship between owl numbers and the availability of the agri-forest patchwork. Aims To model habitat...
Barn and Long-Eared Owl Diets: A Comparative Study from Central Pennsylvannia and a Key for Identification of Prey Items
Jan 01, 2010; Abstract - Two sympatric owl species, Tyto alba (Barn Owl) and Asio otus (Long-eared Owl), are found in Lewisburg, PA. These...