Short-eared Owl - Asio flammeus
Calls - Asio flammeus
Introduction: The Short-eared Owl is a medium-sized owl with relatively long wings, and tiny, often concealed ear-tufts set near the centre of the forehead. 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.
[For help with terms used in the description, see parts of an owl. For general characteristics common to most owl species, see owl physiology.]
Description: The facial disc is ochre, shading into blackish around the eyes. Loral bristles and eyebrows are whitish. Eyes are pale yellow to sulphur-yellow, sometimes bright yellow. The cere is greyish-brown and the bill blackish-horn. The tiny ear-tufts are set close together near the centre of the forehead, often not visible, and erected only when excited. The crown and nape are distinctly streaked dark on yellowish-tawny.
Upperparts are yellowish-tawny to pale ochre-buff with a faint greyish cast, heavily streaked and spotted dusky. The scapulars have dark centres and pale edges. The basal half of the primaries above are plain ochre, contrasting with a narrow area of blackish feathers (alulae) at the 'wrist', which is distinctly visible in flight. The rest of the flight feathers are barred light and dark. The tail is slightly wedge-shaped, and yellowish-tawny with a faint greyish cast and 4-5 visible dark bars.
Underparts are pale yellowish-tawny to ochre-whitish, distinctly streaked brown. Undersides of the secondaries are faintly barred or plain.
Tarsi and toes are feathered pale tawny to whitish-cream. Claws are greyish-horn with darker tips.
Size: Length 33-43cm. Wings length 281-335mm. Tail length 130-157mm. Weight males 206-396g, females 260-475g. Females are 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 day length. 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 this 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 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
has relatively small nesting territories and home ranges, varying from 15 to 200 hectares, 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, 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 old growth 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 and North and South America. Northern populations are migratory and nomadic. Movements of up to 2,000 km have been documented.
Distribution of the Short-eared Owl Asio flammeus
Status: Uncertain. Locally common.
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.
A. f. flammeus,
A. f. bogotensis,
A. f. domingensis,
A. f. pallidicaudus,
A. f. ponapensis,
A. f. portoricensis,
A. f. sandwichensis,
A. f. sanfordi,
A. f. suinda
Campbell, Wayne. 1994. "Know Your Owls". Axia Wildlife
Page compiled by Deane Lewis. Page last updated 2013-07-25
OwlPages.com Owl Species ID: 280.060.000