Northern Hawk Owl

Surnia ulula


Distribution, Migration, and Habitat

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Figure 1. Distribution of the Northern Hawk Owl.

This species is generally distributed very sparsely within the range indicated. During winter, it occurs irregularly south to the dashed line, with rare sightings even further south. This species also breeds in Europe and Asia. See text for details.

eBird range map for Northern Hawk Owl

Generated from eBird observations (Year-Round, 1900-present)

Figure 2. Number of winter-banded Northern Hawk Owls in North America 1956-1992 (n = 363).

Unpublished data from the Bird Banding Office, Canadian Wildlife Service, Ottawa, ON.

Figure 3. Annual cycle of breeding, molt, and migration of N. Hawk Owl

Annual cycle of breeding, molt, and migration of the Northern Hawk Owl in North America. Molt is based in part on European studies. Thick lines show peak activity; thin lines, off-peak.

Northern Hawk Owl breeding habitat, Denali Highway, AK, June.

Typical open black spruce (Picea mariana) forest, where this owl uses tall spruces as hunting perches.; photographer Rick and Nora Bowers

Distribution in the Americas

eBird data provide detailed looks at the range of this species throughout the year: eBird Year-round Range and Point Map for Northern Hawk Owl.

Breeding Range

Unevenly distributed and variable throughout its boreal forest range (Figure 1) (eBird data).

Breeds north to limit of trees in w. and central Alaska (Kodiak I.; Murie 1959, American Ornithologists' Union 1983), n. and central Yukon (Lapierre House, Old Crow, Kluane Lake, Firth Valley, Dempster, Klondike Valley; Sinclair et al. 2003), nw. and central NW Territories (Mackenzie Delta, Anderson River, Great Slave Lake; Godfrey 1986), s. Keewatin (Gagnon Lake; Duncan 1993), n. Alberta (Wadlin Lake, Little Kakwa River; rare and local; Fed. Alberta Nat. 2007), n. Saskatchewan (Fond du Lac, Lake Athabasca; ), n. Manitoba (Churchill, Gillam; JRD, PAD; ), n. Ontario (Kiruna Lake, Moosonee; Cadman et al. 2007), n. Québec (Kuujjuaq, Hutte Sauvage Lake; Godfrey 1986, Bombardier and Gauthier 1996), Labrador (Okak, Udjuktok Bay; Todd 1963), and Newfoundland (northeast of Stag Lake Provincial Park, Nicholsville; J. Maunder pers. comm.). Not found breeding in recent surveys in the Maritime Provinces (

Breeding range extends south to s.-coastal Alaska (Kodiak I.; American Ornithologists' Union 1983), s. British Columbia (Atlin, Peace River district, Tod Mtn., Manning Provincial Park; Campbell et al. 1990b), s.-central Alberta (Banff, Red Deer, Calgary; see above), central Saskatchewan (Hudson Bay Junction; Smith 1996b), and s.-central Manitoba (Minnedosa, Riverton, Kalevala; Godfrey 1986, JRD, PAD; see also above).

Periodically, breeds casually south of breeding range, with population fluctuations and winter irruptions (Duncan 1993). Rarely se. Manitoba (Vassar, Whitemouth Lake, Sprague; Duncan 1993, R. Nero and H. Copland pers. comm.), n. Minnesota (Roseau, Norman, St. Louis, Lake of the Woods, and Aitkin Cos.; , Svingen et al. 2001, Svingen and Nicoletti 2005), n. Wisconsin (Green 1963), n. Michigan (?), s.-central Ontario (Parry Sound, Chapleau, Ottawa; Cadman et al. 2007), s. Québec (Lochaber Bay, Lake Malin; Bombardier and Gauthier 1996, M. Lepage pers. comm.), s. New Brunswick (Tabusintac, Pt. Lepreau, Grand Manan Is.; Erskine 1992a), and s. Newfoundland (Grand Lake, Bay d'Espoir; Erskine 1992a, J. Maunder pers. comm.).

After influx, invasion, or irruption years, southernmost breeding records include n. Idaho, Gulf of St. Lawrence (Bendire 1892b, Cyr and Larivee 1995a), and extreme nw. Montana (S. Gniadek pers. comm.).

Winter Range

Generally resident throughout breeding range, but tends to wander south irregularly in winter to s. Canada and n. Minnesota, rarely to Washington, w. Oregon, Idaho, Montana, N. Dakota, S. Dakota, central Minnesota (Janssen 1987), Iowa, Wisconsin (Robbins 1991), n. Illinois, s. Michigan, n. Ohio; casual as far south as Nebraska, s. Ohio, W. Virginia, Pennsylvania, New York, New Jersey, Connecticut, Massachusetts, and Rhode Island (Bent 1938b, American Ornithologists' Union 1983, Johnsgard 1988a, Eckert 1992, Conrads 1993, Duncan 1993) (eBird data).

Distribution Outside the Americas

Breeding Range

In Eurasia (eBird) from n. Scandinavia, n. Russia, and n. Siberia south to central Russia, n. Mongolia, n. Manchuria, Amur Oblast, and Sakhalin (Cramp 1985a). Periodic variation in breeding range noted with population fluctuations and winter irruptions (Hagen 1956, Cramp 1985a). Circumpolar global range estimated to be 36 million square kilometers; fourth largest of 22 northern forest owls (Clark et al. 1987b).

Winter Range

Same as breeding range, but tends to wander south irregularly in winter to British Isles, continental Europe, and s. Russia (American Ornithologists' Union 1983, Cramp 1985a) (eBird data). Scandinavian and other populations involved in irruptive movements northeast to southeast up to 1,860 km (Cramp 1985a).

Nature of Migration

Like the Great Gray Owl (Strix nebulosa), this hawk owl leads a nomadic life, dispersing extensively within its breeding range in response to regional food availability and therefore to climatic conditions (Svärdson 1957, Andersson 1980, Mikkola 1983). Populations in North America and Eurasia follow closely the cycles of rodent prey, but hare cycles appear also to drive North American populations (Rohner et al. 1995). When prey levels are adequate, Northern Hawk Owl breeds and winters within northern forests, yet high vole (Microtus, Clethrionomys) population abundances can result in temporary southward extensions of its breeding range (Lane and Duncan 1987, Lauff 1997); see Distribution, above). Some remained to breed in s. Manitoba or n. Minnesota in 1987 and 1997 following a major hawk owl irruption, when spring was late, snow cover thick, and voles numerous (JRD, PAD).

Irruptions may occur when vole populations crash at 3- to 5-yr intervals (Mikkola 1983, Duncan 1993). Owl irruptions are less predictable than prey population crashes because vole cycles can vary geographically (Hagen 1956). Low breeding densities and remoteness of breeding habitat are challenges to research on the relationship between prey availability and hawk owl irruptions. Influence of snow cover on prey availability is critical to understanding irruptions and warrants further study.

Irrupts southward in some winters past the northern tier of U.S. states; rarely wanders south to Nebraska, Ohio, Pennsylvania, and New Jersey (Torres 1990). Irruptive flights occur in the Old and New World; such flights have been more extensive in North America than in Eurasia, and more conspicuous in the 19th century than in the 20th (Voous 1988b). Extensive irruptions occur when prey populations crash over large areas (Cramp 1985a).

Large winter irruptions are herein considered to involve at least 3 Canadian provinces or North American regions (cf.Cramp 1985a). In Oct and Nov 1884, hundreds of specimens were taken in n. New England (Barrows 1912b). In Manitoba, also abundant in fall/winter of 1884–1885, with > 50 records (Thompson 1891). A series of irruptions occurred in ne. North America in winters starting in 1877, 1884, 1886, 1895, 1913, 1926, 1928, 1935, 1938, 1939, 1945, 1956, 1957, 1962, 1964, 1966, 1969, 1973–1975, 1978, 1981, 1982, 1985, 1987, 1988, 1990, 1991, 1995, and 1996 (Barrows 1912b, Snyder 1928, Saunders 1937, Bernard and Klugow 1963, Smith 1970a, Speirs 1985, Smith et al. 1988a, Haas 1991, Eckert 1992, Erskine 1992a, Cyr and Larivee 1995a, JRD, PAD).

Likewise, noteworthy irruptions occurred in the n. Great Plains region of central North America in winters starting in 1869, 1876, 1884, 1892, 1898, 1905, 1925, 1926, 1935, 1944, 1950, 1962, 1964, 1965, 1969, 1971, 1975, 1976, 1977–1979, 1982, 1985, 1986, 1990, 1991, 1995, and 1996 (Thompson 1891, Kumlien and Hollister 1903, Swales 1910, Barrows 1912b, Roberts 1932c, Bernard and Klugow 1963, Green 1963, Kehoe 1982, Taylor 1983c, Janssen 1987, Lane and Duncan 1987, Robbins 1991, Eckert 1992, Wilson 1993b, James 1994, Nero 1995, Eckert 1996, Svingen 1997b, JRD, PAD).

See Cramp 1985a for a summary of Eurasian irruptions.

Timing and Routes of Migration

Movements generally unstudied in North America. Fall appearances south of the breeding range occur from mid-Oct through late Nov, with exceptionally early arrivals in invasion years; earliest date 15 Sep (see Figure 3). Spring movement in s. Canada and the n. U.S. from late Feb through early Apr, with stragglers present in May in invasion years; latest date in Minnesota 21 May (Roberts 1932c, Green and Janssen 1975). Winter distribution (number banded and observed) south of regular breeding range suggests that irruptions occur in northwest-to-southeast direction in central (inland) North America; irruptions in w. and e. North America appear to run north to south (JRD). Same data suggest that irruptions occur over > 1 winter (see Figure 2). Back-to-back winter irruptions in 1995–1996 and 1996–1997 were carefully documented in Minnesota (Svingen 1997b). Individuals likely disperse and/or migrate independently.

Paler S. u. ulula believed to wander occasionally to w. Alaska (T. Osborne pers. comm.), and darker S. u. caparoch to the n. British Isles (Guiguet 1978b) and the Canary Is. (Cramp 1985a).

Adult female and juvenile hawk owls disperse earlier and travel farther than adult males because males are more influenced by competition for suitable nest sites (Byrkjedal and Langhelle 1986). During hawk owl irruptions in Sweden in 1950, 85% of birds were juveniles, 15% adults (n = 80 birds; Cramp 1985a); in Finland in 1976, all birds were juveniles (n = 52 birds); of Finnish specimens from south of normal breeding range with varying dates, 88% were juveniles and 12% adults (n = 150 birds; Forsman 1980a). Museum specimens obtained during winter from across North America should be examined to obtain similar data on age and sex during dispersal.

Migratory Behavior

Of 504 hawk owls banded in North America (1956–1992), 8 reported as recaptured (1) or recovered dead (7; Bird Banding Office, Canadian Wildlife Service, Ottawa). Three were in same location where banded after up to 80 d; remaining 5 had traveled as follows (distance [timing, province/state, azimuth]): 259 km (Dec–Mar, New York–Québec, 0°); 97 km (Apr–May, Alaska, 91°); 38 km (Dec, Alberta, 241°); 23 km (Dec–Mar, Minnesota, 214°); 19 km (Jan–Jul, Alaska, 180°).

In Russia, irrupting hawk owls cover great distances and travel highly variable directions (Dement'ev and Gladkov 1966). Banded individuals in Fennoscandia and Russia have dispersed > 1,000 km (Glutz Von Blotzheim and Bauer 1980).

Control and Physiology of Migration

No data.

Habitat in Breeding Range

Typically, moderately dense coniferous or mixed coniferous-deciduous forests bordering marshes or other open areas, such as those cleared by fire or logging. Extends north to tree line, including taiga/tundra ecotone; parallels southern limit of Snowy Owl (Nyctea scandiaca). In mountainous areas, extends upward to timberline, as high as 2,650 m elevation (Campbell et al. 1990b).

Favors open areas with suitable perches: muskegs, scrubby spruce (Picea) growths, forest glades, second-growth mixed hardwood and conifer woodlands, tamarack (Larix) swamps, dry ridges, stunted trees at timberline, burned areas, clearings, and swampy valleys or meadows (Mikkola 1983, Cramp 1985a, Voous 1988b). In Alaska, prefers open-canopied forests (20–60% canopy cover) or forest edges (Meehan and Ritchie 1982); also old mature spruce stands (Torres 1990). Avoids dark, impenetrable spruce-fir (Picea-Abies) forests (Voous 1988b).

One of many wide-ranging birds that Erskine (Errington 1933) considered more characteristic of conifer than of broadleaf forests, although by no means restricted to them. Habitat locations determined by abundance of prey populations, regardless of other factors (Cramp 1985a).

Fire considered important in providing nest sites (snags, burnt or rotted-out cavities, increased number of woodpecker cavities), increasing small-mammal and open hunting habitat (Ball 1954, Mindell 1983b, Peck and James 1983, JRD, PAD). More abundant in burned boreal forests than in unburned forests; burns suitable for up to 8 yr with maximum densities of 3 nests/100 km2 in second year post-fire (Hannah and Hoyt 2004). Storm-damaged trees also an important source of nest trees (Taylor 1983c).

Best breeding habitat in North America is likely noncommercial or “forest and barren” area to north where forests are more open (Duncan 1993, Austen et al. 1994). Occasionally nests in aspen parkland (Populus) after winter irruptions south of typical boreal forest breeding range (Duncan 1993).

See also Breeding: nest site, and Behavior: self-maintenance, below.

Habitat in the Overwintering Range

Generally same as breeding habitat. During irruptions, wooded farmlands and sometimes prairie areas where haystacks, posts, or available trees or bushes are used as perches (Johnsgard 1988a). In Minnesota and Manitoba, observed hunting in old burns, cutovers, riparian forests, and agricultural land (Lane and Duncan 1987, Nero 1995). Uses second-growth woodlands and lakeshores in British Columbia (Campbell et al. 1990b).

Historical Changes to the Distribution

Few data. Historically, may have nested in extreme nw. Montana, n. Idaho, Minnesota, and n. Michigan (Bent 1938b); hence, recent southern nests probably do not represent extension of breeding range. Probably crossed Bering Land Bridge from Asia to North America during the last ice age (Voous 1988b).

Fossil History

No fossil relatives known; present in late Pleistocene in Tennessee, U.S. (Wisconsin cave deposits), France (end of Würm Glacial, department of Isère), and in Switzerland, Austria, and Hungary (Riss-Würm Interglacial; Parmalee and Klippel 1982, Voous 1988b).

Recommended Citation

Duncan, J. R. and P. A. Duncan (2014). Northern Hawk Owl (Surnia ulula), version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.