Species: Asio flammeus

See Johnsgard (1988) for egg dates (timing of nesting varies with latitude and prey abundance). Often only the oldest chicks survive. <br><br>COURTSHIP AND TERRITORIAL DEFENSE: Wing-clapping, exaggerated or deep wing-beats, and skirmishing are three displays seen predominantly during the breeding season (Lockie 1955, Clark 1975). Short-eared owls wing-clap along territorial boundaries or during flights within a territory, in aggressive displays to other birds or to human observers, and in courtship flight. When wing-clapping, the owl's wings are brought below the body and clapped together in short, rapid bursts. Both males and females may wing-clap. The courtship flight is unique and involves song, a spiraling flight, and wing-clapping by the male (DuBois 1924, Mikkola 1983, Holt 1985). Exaggerated wing-beats also occur in the same contexts as wing-claps. In this behavior the owl brings its wings high over its body, prominently displaying the underwing. Owls often patrol territorial boundaries using exaggerated wing-beats. Skirmishing involves other neighboring owls, usually along territorial boundaries, and is aggressive and territorial in nature. Exposure of talons, hovering, and sometimes actual striking of the other bird is involved. Any of these displays observed during the breeding season may signify a territorial bird. Observation and mapping of these behaviors over a nesting season is the best way to delineate an owl's breeding territory (Lockie 1955, Village 1987, Tate 1991). <br><br>Generally begin courtship in mid- to late March on Nantucket Island along the coast of Massachusetts (Holt and Melvin 1986; Tate and Melvin 1987, 1988). Courtship has been reported as occurring in mid-March in Montana (Dubois 1924) and as early as late February in Jefferson County, New York (G. Smith, pers. comm.). Pitelka et al. (1955) reported initial courtship activity in the first week of June at Barrow, Alaska. Unpaired males may engage in courtship flights well into the breeding season (Clark 1975; G. Tate, pers. obs.). The breeding season is often reported to commence in direct relation to vole abundance with a larger prey population yielding an earlier start to breeding activities (Randall 1925, Snyder and Hope 1938, Lockie 1955, Mikkola 1983). <br><br>NESTING: Depending on latitude, nesting activities generally begin in late winter to early spring across the owl's distribution. Timing of nesting may be correlated with latitude and prey abundance (Mikkola 1983, Cramp 1985). The nesting cycle from nest initiation to fledging of young takes approximately seven to nine weeks in temperate zones lasting from mid-March to mid-September in the Northeast Region. During a four-year study of breeding ecology on Nantucket Island, egg-laying began in April each year (as early as the first week) and all young were fledged by the first week of September (Holt and Melvin 1986; Tate and Melvin 1987, 1988; Combs and Melvin 1989). Late nests or renests accounted for young fledging in late August and September (Tate and Melvin 1987, 1988). Polygyny may result in two nests within one short-eared owl territory. On Nantucket, two broods from different females that overlapped temporally were raised within a territory defended by a single male (Tate 1991). <br><br>Unlike most owls that nest in holes or take over the abandoned nests of crows or other birds, the short-eared owl is unique within its family (Strigidae) in building a nest, albeit a crude one, on the ground. The female makes a small scrape in the ground with her body and lines it with nearby material. Nests may be lined with grass, leaves, twigs or feathers (Bent 1938, Clark 1975). These small nest depressions do not last long after the young have dispersed from the site (G. Tate, pers. obs.). <br><br>Generally between four and nine eggs are laid, and sometimes more (Bent 1938), although Mikkola (1983) reported a range of two to 13 from 121 European records. Murray (1976) reported a mean clutch size of 5.61 from 186 nests in North America. A trend for mean clutch size to increase from south to north was also noted in this sample. The largest clutch ever reported in the literature is 16 from Finland (Mikkola 1983). Large clutches of 14 in Scotland (Adair 1982) and 13 from Finland (Mikkola and Sulkara 1969) have also been reported. All exceptionally large clutches were laid in years of peak vole abundance in these areas. <br><br>Clark (1975) reported a mean clutch of 8.6 from five clutches in 1969 in Manitoba, Canada. Pitelka et al. (1955) reported a range in clutch size of four to eight with a mean of 6.3 from 22 nests in Alaska. A four-year study of nesting owls on Nantucket reported clutch sizes of 5.8 (n = 6), 7.7 (n = 9), 6.8 (n = 8), and 5.2 (n = 8) in 1985-88 respectively, with an inclusive range of four to nine (Holt and Melvin 1986; Tate and Melvin 1987, 1988; Combs and Melvin 1989). <br><br>Two broods are sometimes raised and, if the nest is destroyed or depredated, the female may renest (Lockie 1955, Mikkola 1983). Pitelka et al. (1955) saw no evidence of renesting by short-eared owls in Alaska; this was apparently tied to the shorter season. In 1986 and 1987, single late nests with eggs were found on Nantucket in mid-July (G. Tate, unpubl. data). These were suspected to be either second broods or renests. <br><br>Witherby et al. (1938) reported an incubation period of 24-28 days in temperate zones. With data from six eggs in four nests, Pitelka et al. (1955) reported an incubation period for Barrow, Alaska, that ranges from 26-37 days (mean = 30). He saw no evidence that incubation takes longer there than at lower latitudes. From a Finnish study of four nests, Gronlund and Mikkola (1969) reported an incubation period of 24-29 days (mean = 25.7). In 1986, three eggs, each from separate nests on Nantucket, were documented as having 29-, 30-, and 31-day incubation periods (mean = 30) (Tate 1991). <br><br>Normally the female does all of the incubation (Witherby et al. 1938, Dement'ev et al. 1951, Pitelka et al. 1955, Clark 1975) and lays at approximately 24-hour intervals (Mikkola 1983). She begins incubation with the first egg laid and hatching is therefore asynchronous. According to Mikkola (1983), the first and last eggs laid take the same length of time to incubate. Young owls leave the nest before fledging and wander into the surrounding area at about two weeks of age (Lockie 1955, Clark 1975). The young owlets stay concealed but continue to wander and are found and fed by both parents by means of the food-begging call given by the young. Fledging has been reported variously at 24-27 days (Witherby et al. 1938) and 31-36 days (Urner 1923). On Nantucket, young owls dispersed from the nest at 14-17 days and fledged when about 30 days old (Holt and Melvin 1986). <br><br>Age of first breeding is reported as one year or less (Mebs 1966, cited by Mikkola 1983; Glutz von Blotzheim and Bauer 1980). Field evidence of breeding at one year has been obtained on Nantucket in 1990, when a sitting female that had been banded as a nestling in 1989 was trapped. This female was brooding on a nest only 98 m from her natal nest site (K.P. Combs unpubl. data). These owls have been known to live as long as 12.5 years (Mebs 1966, cited by Mikkola 1983). <br><br>Short-eared owls usually offer little defense of the nest from human intruders. Wing-clapping, circling overhead with deep wing beats, "barks" or "yaps," and broken-wing acts are employed when any defense is attempted. Adults perform a distraction display that is a dramatic broken-wing act accompanied by vocalization. It is most often used by the male when an observer is at, or near, a nest or dispersed young (Clark 1975; G. Tate, pers. obs.). However, often both owls vacate the vicinity of the nest site while an intruder is present. At times the female may desert the area, retreating to another part of the breeding territory, while the male remains nearby. Females may return to the nest by flying low and remaining inconspicuous (G. Tate, pers. obs.). <br><br>While short-eared owls have been observed diving at house cats (G. Tate, pers. obs.), the best defense is their cryptic coloration and the fact that the female sits tightly on the nest. On Nantucket, some females remained on the nest while observers passed within two meters, and on Tuckernuck Island, a female on a nest would not budge in spite of repeated attempts from as close as one meter to flush her (G. Tate, pers. obs.). These behaviors make it extremely difficult to find nests.