Montana Field Guide

Short-eared Owl - Asio flammeus

Short-eared Owl tufts are very small and inconspicuous, and are generally not seen except when the female is in a camouflage position at the nest. The species should be considered a round-headed owl for identification. The eyes are yellow and the bill black. The facial disk is circular and grayish-white with black orbits. Juvenile owls retain more black on the disk until fall. Ventrally, they are buffy-brown with vertical streaks and paler on the belly. Dorsally, they are mottled buffy-brown. In flight, the dark "wrist" patch on the underwing is a key field mark, coupled with moth-like flight. The size is 13 to 17 inches and the weight is 11 to 14 ounces. The voice is a "Hooh, hooh, hooh" given approximately 15 times during courtship flight. The courtship song is also accompanied by an audible wing-clap and dive between calls (FWP).

Short-eared Owls are a small to medium-sized owl. Published lengths range from 37 to 39 centimeters (Cramp 1985) to 34 to 42 centimeters (Mikkola 1983), with females slightly larger than males and considerably heavier, averaging 411 grams compared to 350 grams for males (Mikkola 1983). They are excellent flyers with long wings (95 to 110 centimeters) (Cramp 1985), and light wing-loading (0.333 gram per centimeter squared) (Clark 1975). There is little difference in wing length between the sexes (Clark and Ward 1974). The back and upper wing surfaces are tawny-brown to buff-colored with heavy but indistinct streaking. The ventral surfaces are much lighter, with bold, vertical brown streaking on the breast, and a pair of barely visible ear tufts close together at the top of the facial disk. The belly is pale, lightly streaked; the wings are long and have a buffy patch beyond the wrist above and a dark patch at the base of the primaries below; the dark facial disk contrasts with yellow eyes; and the legs and feet are feathered (NGS 1983). Mature males are bright white on the underwing, while mature females show somewhat more buff coloration (Bent 1938, Village 1987). It is, nonetheless, difficult to sex or age these birds in the field. Females are generally darker than males but young birds are also darker than older ones (Mikkola 1983), thus a young male may be darker than an old female. Both sexes have a distinct, black carpal bar and dark wingtips. Juveniles possess full adult plumage by October of the first year (Bent 1938, Cramp 1985). The facial disc is circular and whitish with dark areas around the bright, yellow eyes. Recently fledged and juvenile owls show much darker coloration overall and a much darker facial disc which whitens with age. The owl gets its common name from the small ear tufts over the eyes. These tufts are part of the facial disc and are erected when the bird is annoyed or alert. They may possibly aid in making birds more cryptic when in vegetation by breaking the line of the circular facial disc.

The bird is generally silent but does vocalize in courtship (a low, repeated, hooting "voo, hoo, hoo, hoo", or in conjunction with defensive behavior or annoyance, yaps or barks). Young owls give a food-begging call ("pssssip") that apparently aids adults in locating them from the time they leave the nest until after fledging. Adult owls may squeal while feigning injury during broken-wing acts to distract intruders from nests or young. Both young and adults will clack their bills when annoyed or in defense. Apparently, no data exist on the use of broadcasting tape-recorded vocalizations for detection or monitoring purposes.

Long-eared Owl has a smaller "wrist" patch, buffy underwings, and a darker belly. Although Long-eared Owls hunt similarly to Short-eared Owls, they are rarely seen hunting during the day. Burrowing Owl is much smaller and has a yellow to whitish bill (FWP). These are probably the most diurnal of owls (Lockie 1955, Clark 1975) and may often be observed from late afternoon until nightfall, or at dawn. A crow-sized owl seen abroad during daylight in open country will most likely be a Short-eared Owl. However, they also hunt at night. They are easily recognized by their blunt-headed profile and the fact that they glide with their wings held horizontally. This contrasts with the shallow v-shape of the Northern Harrier (Circus cyaneus) with which the owl often shares habitat and may be confused. Harriers may also be distinguished by their white rump patch. Habitat is useful in separating Short-eared Owls from Long-eared Owls (Asio otis), the latter being predominantly a woodland dweller. The Long-eared Owl is also more slender with much longer ear tufts. Burrowing Owl also inhabits open country but is smaller (24 centimeters vs. 38 centimeters), has relatively longer legs, and (in adults) has at least some horizontal barring on the breast. The Short-eared Owl's style of flight is unique and has at times been called mechanical, moth-like, or even slovenly (Peterson 1934).

Montana Range

Migratory; however, some individuals may not migrate (FWP). Migratory in N parts of range (Johnsgard 1988). Some suggestion of migr. in MT: late Feb - early Mar (Davis 1961).

Open grasslands, plains, and agricultural areas with suitable vegetation and food.

A vole or field mouse specialist - almost the entire diet made up of these small rodents (FWP). A study of owl pellets in Ninepipes NWR yielded a 3.7:1 ratio of female:male MICROTUS (MONTANUS and PENNSYLVANICUS) eaten; snap-trap data yielded a 2.4:1 ratio (Holt and Williams 1995); it is impossible, however, to conclude from this data that owls were preferentially selecting females over males, as there could be more females in the prey population.

Begins nesting in late February to March. Nests on the ground in a small depression, often with grasses placed around the depression; nest resembles a small bowl. Clutch size four to ten. Incubation approximately 26 days. Young fledge at 30 to 40 days (FWP). Egg records are from Apr 3 - June 13 (Davis 1961).