Short-eared Owl Fact Sheet
Short-eared Owl
Asio flammeus
New York Status: Endangered
Federal Status: Not Listed
Description
Short-eared owls are medium size owls with small ear tufts that appear as two ridges along the top of the head. They have round, beige facial disks similar to those of barn owls. The underparts are white/buffy (male) or tawny/rust (female), and streaked with brown, while the back is brown and mottled with white. When perched the wings extend beyond the tail and in flight the undersides of the wings show dark markings on the wrists and primary tips. The short-eared owl's flight is frequently described as "moth or bat-like" because it flies low over grasslands or marshes, moving back and forth with unhurried, irregular wingbeats.
Short-eared owls are the most diurnal of all the northeastern owls. They are most often observed in the late afternoon and at dawn or dusk. These birds eat primarily small mammals, but they occasionally take small birds and the young sometimes eat insects. When hunting short-ears dive from perches or fly low over the ground and pounce on prey from above, sometimes hovering briefly before they drop.
Life History
Short-eared owls opportunistically inhabit areas where small mammals, especially meadow voles (Microtus pennsylvanicus), are abundant. Their breeding sites, the number of wintering birds, the number of nesting pairs, and the number of eggs or young may change from year to year based on the food supply. Breeding begins in March when both sexes begin defending territories and courting with elaborate flight displays that include wing-clapping, exaggerated wing-beats, and skirmishing. Nests are placed on the ground where the female creates a cup and lines it with grasses and down. Four to nine eggs are typical, but clutches as large as fourteen have been reported in years of peak small mammal abundance. Incubation, which is done by the female alone, lasts about a month. The eggs hatch asynchronously and fledging occurs about a month later.
In winter short-eared owls gather in open habitats that support large numbers of voles. When food is abundant they may form large communal roosts of up to 200 birds in sheltered sites ranging from conifers to stump piles to abandoned quarries. Deep snow and ice may reduce the availability of prey locally and cause the owls to abandon wintering areas occupied earlier in the season. However, where food remains plentiful into the spring and summer, wintering areas may become breeding sites.
Distribution and Habitat
Short-eared owls are widely distributed breeding in marshes, grasslands, and tundra throughout North America and Eurasia, and on every continent except Australia. They are also found on islands such as Iceland, the Hawaiian Islands, the Greater Antilles, and the Galapagos. They are birds of open county. Within their extensive global range they occur wherever small mammals are abundant, favoring habitats such as prairies, coastal grasslands, heathlands, shrub-steppe, and tundra.
Although there are scattered breeding records in the east as far south as Virginia, New York is at the southern edge of this owl's breeding range. Northern populations are believed to be highly migratory, and there is a marked increase in the number of birds in New York in the fall and spring. Short-eared owls are more common as winter residents than as breeders. They winter in significant numbers in the Finger Lakes and the Lake Ontario lake plain, especially in Jefferson County, at a few scattered sites in the Hudson Valley, and on the south shore of Long Island. As breeders they are very rare, being limited to the St. Lawrence and Lake Champlain Valleys, the Great Lakes plains and the marshes of Long Island's south shore.
Status
Early in the twentieth century Eaton called the short-eared owl "one of our commonest owls" outnumbering all other owls in lowlands and marshy areas. By 1974 it was already considered a local breeder, declining in numbers. A comparison of historical and modern breeding records show that this species may have been lost as a breeder from eastern Suffolk County and the upper Hudson Valley. However, in the last 20 years new breeding sites have been documented in the St. Lawrence and Champlain valleys and east of Lake Ontario.
In the Northeast region five of the thirteen states list short-eared owls as endangered while two others include them on their state lists at lower levels of conservation concern. Historically these owls bred in at least eight states in the Northeast but today they nest only in Massachusetts, New York, Vermont, and Pennsylvania. Most biologists believe reforestation and the loss of open habitats are largely responsible for this decline.
Management and Research Needs
Short-eared owls have probably never been common as breeders in New York but our knowledge of their status and distribution may be incomplete because they occur in some parts of the state that are sparsely populated, breed early in the season, and hunt late in the day. Targeted surveys in appropriate habitats near wintering areas might shed new light on this bird's status and distribution as a breeding species in New York.
The conservation of short-eared owls in New York depends on protecting relatively large, open sites that support small rodents. Except for a few large marshes, most of the nest sites recorded in recent years have been found on farms, typically in active hayfields or pastures where the nests and young birds are sometimes mowed or plowed. Once abandoned, agricultural sites rapidly become unsuitable for owls because they succeed to woodlands or are replaced by development. In order to protect short-eared owls it will be necessary to identify suitable nesting sites that can be managed for small rodents and owls. Such management will likely have the added benefit of protecting other imperiled grassland birds with similar habitat requirements.
Additional References
Bosakowski, T. 1986. Short-eared owl roosting strategies. American Birds 40: 237-240.
Clark, R. J. 1975. A field study of the short-eared owl (Asio flammeus) Ponoppidian in North America. Wildlife Monographs 47: 1-67.
Cooper, M. F. 1998. Short-eared owl, Asio flammeus. Pages 337-338 in Bull's Birds of New York State (E. Levine, Ed.). Comstock, Ithaca, NY.
Eaton, E. H. 1914. Birds of New York State, part 2. University of the State of New York, New York State Museum, Albany, NY.
Holt, D. W. and S. M. Leasure. 1993. Short-eared owl Asio flammeus. In The Birds of North America No. 62 (A. Poole and F. Gill, Eds.). The Academy of Natural Sciences, Philadelphia, PA; American Ornithologists' Union, Washington, DC.
Drawings by Jean Gawalt
