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 Galpagos Islands. 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, 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. These owls hunt over open fields or grasslands, taking mainly rodents, other small mammals and some birds.
Because they are active during the day, Short-eared Owls are easier to see than most other owls. They are especially active at dawn and dusk, and they perform dramatic courtship flights, complete with vocalizing and wing clapping, during the breeding season. They are chase-predators and hunt by flying low over an open area, with their wings at a slight dihedral, somewhat like Northern Harriers. Their buoyant wing-beats give them a distinctive moth-like appearance.
Listen to the sound of Short-eared Owl
Copyright remark: Most sounds derived from xeno-canto
The Short-eared Owl nests on the ground, unlike most other Owls. Nests are usually situated in the shelter of a grass mound, under a grass tuft, or among herbaceous ground cover. Nests are loosely constructed by the female, who scrapes a spot on the ground and then lines the scrape with grass stems, herb stalks, and feathers plucked from her breast. Clutch sizes range from 4 to 14 eggs (average 5 to 7), with large clutches laid during years of high food abundance. Clutch size increases from south to north. Eggs are laid every 1 to 2 days and incubation commences with the first. Incubation is done largely by the female, with the male bringing food to the nest and occasionally taking a turn incubating. Young grow very rapidly after hatching, and begin to wander from the nest as soon as 12 days, an adaptation for a ground-nesting species to reduce the amount of time they are vulnerable to predation. Young fledge at about 4 weeks.
The Short-eared Owl routinely lays replacement clutches, because of high predation rates. In southern areas, it may raise 2 broods in 1 year. Because reproductive success is relatively poor, the ability to lay large clutches helps populations recover after periodic declines.
The Short-eared Owl is highly migratory, and nomadic, except in southern parts of its range. Movements of up to 2,000 kilometers have been documented. This Owl has relatively small nesting territories and home ranges, varying from 15 to 200 hectares (35 to 500 acres), and may nest in loose colonies in excellent habitat. Because of its nomadic tendencies, mate and site fidelity are very low. Breeders tend to wander until they find areas with high densities of prey before settling to breed. In winter, large numbers of Owls will occur in areas with lots of food. Communal winter roosts of up to 200 birds are known, with these birds ranging over nearby areas to hunt. Resident Owls will defend winter foraging territories of about 6 hectares (15 acres), before expanding the territory size during the breeding season.
Video Short-eared Owl
Asio flammeus is a widespread but patchily distributed breeder across much of Europe, which accounts for less than a quarter of its global breeding range. Its European breeding population is relatively large (>58,000 pairs), but underwent a large decline between 1970-1990. Although declines continued in a few countries during 1990-2000, they abated across most of Europe, and the species was broadly stable overall. Nevertheless, its total population size remains below the level that preceded its decline.
This owl inhabits a large part of Eurasia, North America and southern South America. In Europe, especially in the south, its distribution is increasingly fragmented. The total population of the European Union is estimated at 1500-3500 breeding pairs. It fluctuates according to rodent densities, but seems to decrease following mainly habitat loss, but also persecution and use of pesticides (especially rodenticides). Many birds are also killed along roads and railways.
Fluctuations in the Short-eared Owl population, due most likely to cyclical variation in the population of voles, make it difficult to determine long-term trends. However, declines have been recorded from many parts of the owls’ range, and Short-eared Owls are listed as an at-risk species by Partners in Flight. Development and agriculture, which result in loss of habitat, are the most significant threats to the population.