Short-eared Owl - Asio flammeus

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Calls - Asio flammeus

Typical Male		© Brinzal
Female response (?)		© Brinzal

A Danish bishop and amateur naturalist, Erich Ludvigsen Pontoppidan, published the first description of this Owl in 1763. In Latin, the word "flammeus" means fiery, flaming, or the colour of fire. Local names for the Short-eared Owl include the Evening Owl, Marsh Owl Bog or Swamp Owl, Grass Owl, Meadow Owl, Mouse-hawk, and Flat-faced Owl.

Description: The Short-eared Owl is a medium-sized Owl. The plumage is buffy brown with dark streaks on the chest, belly, and back. Males tend to be lighter in colour than females. This colouring provides good camouflage, but if this fails, a Short-eared Owl will feign death to avoid detection. The wings and tail are strongly barred. The yellow eyes are circled with black and set in whitish or buffy-white facial disks, which are suffused with a ring of brown. The bill is black. The head appears round without ear tufts, but at very close range small ear tufts are visible. In flight, the dark "wrist" on the underwing is the key field mark.

Size: Lengths 33-43cm (13-17") Wingspan female 107cm (42"), male 105cm (41") (averages)
Weight 206-475g (7-17oz) Females are slightly larger than Males.

Habits: Generally nocturnal, but often become active 30-60 minutes before sunset; some owls may be active during the day (to a much lesser extent) during the breeding season. Seasonal changes in activity a response to variations in vole population size and daylength. Flies with deep, slow, moth-like rowing wingbeats, and glides on stretched wings over open landscapes. Outside breeding season, they may gather in communal roosts. A largely nomadic vole-specialist.

Voice: Short-eared Owls are generally quiet, owing to their diurnal nature and the wide open habitats where visual displays would are more effective than in forests. The male's territorial song is a pulsing "voo-hoo-hoo", resembling an old steam engine. This song is given mainly during flight displays and the female responds with a barking "kee-ow". Both sexes give hoarse cheeaw calls when disturbed in their nesting territory. When excited near the nest, both sexes squawk, bark, hiss and squeal.

Hunting & Food: Short-eared Owls hunt mainly at night and during the morning and late afternoon. They fly over open areas, a few feet above ground, and pounce when prey is located. In dense vegetation they will hover over prey, often for extended periods when facing into the wind, before pouncing. They occasionally hunt from a perch or while standing on the ground. Short-eared Owls eat mainly small mammals, but sometimes take birds. Meadow voles (Microtus species) are the primary prey. Deer mice, shrews, ground squirrels, pocket gophers, pocket mice, moles, rats, bats, rabbits, and muskrats are also taken. Birds probably are more important when Short-eared Owls hunt in marshes and along coastal areas, where they can target shorebirds, terns, and small gulls and seabirds. In inland habitats they take mainly Horned Larks, meadowlarks, blackbirds, and pipits. A few insects such as roaches, grasshoppers, beetles, katydids, and caterpillars are also taken. Unlike most Owls, prey is normally carried in its talons.
Short-eared Owls and Northern Harriers often harass each other when hunting the same field, and harriers often steal food from the Owl.

Breeding: Courtship and territorial behaviour is spectacular for an Owl. Males perform aerial displays by rising quickly with rhythmic and exaggerated wing beats, hovering, gliding down, and rising again, often 200 to 400 meters (650 to 1,300 feet) above ground. Wing claps, in bursts of 2 to 6 per second, are often made during this flight and some singing occurs. The flight can be ended with a spectacular descent where the male hold his wings aloft and shimmies rapidly to the ground. Two birds may engage in flight, locking talons, and fighting briefly. Often, a display where one bird flashes its light underwing towards another is used during territorial and courtship flights. 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 kilometres (1,200 miles) 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.

Mortality: Wild Short-eared Owls have reached almost 13 years of age. Natural enemies include many diurnal raptors such as the Bald Eagle, Northern Goshawk, Gyrfalcon, Red-tailed Hawk, and Snowy Owl. Because they nest on the ground, they are vulnerable to mammalian predators such as skunks, dogs, foxes, and coyotes, while Jaegers, gulls, ravens, and crows steal eggs and small chicks. Collisions with vehicles account for a large number of deaths. Also, They are attracted to the wide open fields of airports and so many are killed by collisions with aircraft.

Habitat: Short-eared Owls inhabit wide open spaces such as grasslands, prairie, agricultural fields, salt marshes, estuaries, mountain meadows, and alpine and Arctic tundra. Breeding habitat must have sufficient ground cover to conceal nests and nearby sources of small mammals for food. Communal roosts occur in oldgrowth fields, along thick hedgerows, in overgrown rubble in abandoned fields, or in clumps of dense conifers. These Owls tend to roost in trees only when snow covers the ground. During migration, Short-eared Owls will move through high mountain passes, flying at great heights.

Distribution: Short-eared Owls occur widely in the Old World, in Iceland, the Hawaiian Islands, Galapagos Islands, and North and South America.

Status: Uncertain.

Original Description: Pontoppidan, Erik. 1763. Den danske atlas eller konge-riget Dannemark, med dets naturlige egenskaber, elementer, indbyggere, vaexter, dyr og andre affodninger, dets gamle tildrageiser of naervaerene omstaendigheder i alle provintzer, staeder, kirker, slotte of herregaarde (Dansk. Atlas) 1, p. 617, pl. 25.

Subspecies: A. f. flammeus, A. f. bogotensis, A. f. domingensis, A. f. galapagoensis, A. f. pallidicaudus, A. f. ponapensis, A. f. portoricensis, A. f. sandwichensis, A. f. sanfordi, A. f. suinda