Short-eared Owl

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Image:ShortearOwl.jpg

Common Name: Short-eared Owl
Scientific Name: Asio flammeus

Size: 13.4–16.9 inches (34-43 cm); Wingspan: 33.5–40.6 inches (85-103 cm)

Habitat: Worldwide; 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.

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.

Status: Least Concern to Vulnerable. Global population: >2,000,000 adult individuals with an decreasing population trend. Short-eared Owl populations declined by 2.5 percent per year between 1966 and 2010, resulting in a cumulative decline of 67 percent, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 3 million with 14 percent spending some part of the year in the U.S., 11 percent in Canada, and 3 percent wintering in Mexico. The 2014 State of the Birds Report listed them as a Common Bird in Steep Decline, and they rate a 12 out of 20 on the Partners in Flight Continental Concern Score. These owls are listed as of special concern, threatened, or endangered in some states. They are more common in the northern portion of their breeding range, but populations fluctuate greatly along with prey population cycles.

Diet: Mostly 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.

This owl is 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 are a response to variations in vole population size and day length. 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.

Nesting: Males and females are alike however males tend to be up to 8% heavier than females. The facial disc is ochre, shading into blackish around the eyes. Loral bristles and eyebrows are whitish. Eyes are pale yellow to sulfur-yellow, sometimes bright yellow. The cere is grayish-brown and the bill blackish-horn. The tiny ear-tufts are set close together near the center of the forehead, often not visible, and erected only when excited. The crown and nape are distinctly streaked dark on yellowish-tawny. Upper parts are yellowish-tawny to pale ochre-buff with a faint gray cast, heavily streaked and spotted dusky. The scapulars have dark centers and pale edges. The basal half of the primaries above are plain ochre, contrasting with a narrow area of black 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 yellow-tawny with a faint grayish cast and 4-5 visible dark bars. Underparts are pale yellow-tawny to ochre-white, distinctly streaked brown. Undersides of the secondaries are faintly barred or plain. Tarsi and toes are feathered pale tawny to whitish-cream. Claws are grayish-horn with darker tips.

Courtship and territorial behavior 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 under-wing 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.

This Owl 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..

Cool Facts: In Latin, the word "flammeus" means fiery, flaming, or the color of fire. Common names for this owl also include the Evening Owl, Marsh Owl, Bog or Swamp Owl, Grass Owl, Meadow Owl, Mouse-hawk, and Flat-faced Owl.

The Short-eared Owl may compete with the Barn Owl in some areas. Some successful nest box programs to attract Barn Owls have coincided with the decline of the Short-eared Owl in the same area.

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.

There are 10 subspecies of Short-eared Owl:

  • A. f. bogotensis. First reported by Chapman in 1915. It is found in Colombia, Ecuador and northwestern Peru.
  • A. f. domingensis. First reported by Statius Müller in 1776. It is found on Hispaniola.
  • A. f. flammeus. First reported by Pontoppidan, 1763. The nominate species, it is found in North America, Europe, northern Africa and northern Asia.
  • A. f. galapagoensis. First reported by Gould in 1837. It is found on the Galápagos Islands.
  • A. f. pallidicaudus. First reported by Friedmann in 1949. It is found in Venezuela, Guyana and Suriname
  • A. f. ponapensis. First reported by Mayr, 1933: found on east Caroline Island.
  • A. f. portoricensis. First reported by Ridgway in 1882. It is found in Puerto Rico
  • A. f. sandwichensis. First reported by A. Bloxam in 1827. The Pueo or Hawaiian short-eared owl is found in the Hawaiian Islands.
  • A. f. sanfordi. First reported by Bangs in 1919. It is found on the Falkland Islands
  • A. f. suinda. First reported by Vieillot in 1817. It is found from southern Peru and southern Brazil to Tierra del Fuego.
  • A. f. cubensis. First reported by Garrido, 2007. It is found in Cuba.


Found in Songbird ReMix Owls of the World Volume 2

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