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BC Conservation Data Centre: Species Summary


Surnia ulula
Northern Hawk Owl

 
Scientific Name: Surnia ulula (Linnaeus, 1758)
English Name: Northern Hawk Owl
 
Classification / Taxonomy
Scientific Name - Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Classification Level: Species
Species Group: Vertebrate Animal
Species Code: B-NHOW
Kingdom Phylum Class Order Family
Animalia Craniata Aves Strigiformes Strigidae
   
Conservation Status / Legal Designation
Global Status: G5 (Apr 2016)
Provincial Status: S4S5 (Mar 2015)
BC List: Yellow
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status: Not at Risk (May 1992)
SARA Schedule:
General Status Canada: 4 - Secure (2005)
Migratory Bird Convention Act:
   
Ecology & Life History
General Description:
Global Reproduction Comments: Egg dates: late April to mid-June in Alaska and arctic Canada; April-early June in Alberta. Clutch size is up to 13 (mean brood size was 6.3 in Fennoscandia, 3.7 in Yukon, 5.5 in Alaska). Incubation lasts about 25-30 days, by female. Both parents tend young, which fledge in 25-35 days, independent in about 3 months.
Global Ecology Comments: Tends to occur in greatest numbers in areas with temporarily high prey populations; may move long distances in response to changes in prey abundance. Population density generally is low (e.g., 4 pairs in 200 sq km in Norway; 1 pair per 500 sq km in Sweden) (Johnsgard 1988); maximum of 3 nests per 100 sq km in southwestern Yukon, Canada (Rohner et al. 1995). Home ranges in Europe ranged from 140 to 848 hectares, average 372 hectares (Baekken et al. 1987).
Migration Characteristics:
(Global / Provincial)		 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant: 		Y /
Y /
N /
na /
Global Migration Comments: Basically nonmigratory but retreats slightly in winter from northernmost part of range (National Geographic Society 1983). Southward irruptive movements generally in year following peak in rodent population. Usually on nesting territory by mid-March in northern Alberta.
Habitats:
(Type / Subtype / Dependence) 		Agriculture / Cultivated Field / Unknown
Agriculture / Hedgerow / Unknown
Agriculture / Pasture/Old Field / Unknown
Alpine/Tundra / Krummholtz / Unknown
Forest / Conifer Forest - Dry / Unknown
Forest / Conifer Forest - Mesic (average) / Unknown
Forest / Conifer Forest - Moist/wet / Unknown
Lakes / Lake / Unknown
Riparian / Riparian Forest / Unknown
Wetland / Bog / Unknown
Wetland / Fen / Unknown
Wetland / Marsh / Unknown
Wetland / Swamp / Unknown
Global Habitat Comments: Open coniferous or mixed forest, forest edge and clearings, old deciduous forest burns, dense shrubby areas (especially tamarack), swamps, scrubby second-growth woodland and muskeg (AOU 1983).

Nests in hollow tops of dead spruces, birches, natural tree hollows, abandoned woodpecker holes, deserted nests of crows and birds of prey (Terres 1980).
Food Habits: Carnivore: Adult, Immature
Invertivore: Adult, Immature
Global Food Habits Comments: Diet often is dominated by voles, but birds (up to grouse size) may comprise the major part of the diet in winter and snowshoe hare juveniles may be important during certain nesting stages (Rohner et al. 1995). Also eats other small mammals and insects. Watches for prey from perch, swoops down on it, returns to elevated perch.
Global Phenology: Circadian: Adult, Immature
Global Phenology Comments: Active any time of day during breeding season; hunts mainly during daylight hours in winter.
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: N
Length(cm)/width(cm)/Weight(g): 41/ / 345
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: BREEDS: from limit of trees in western and central Alaska to southern Keewatin and Labrador, south to southern British Columbia, central Saskatchewan, northern Minnesota, northern Michigan, and New Brunswick. WINTERS: mainly in breeding range, makes irregular invasions of northern coterminous U.S. Also occurs in Old World.
 
Authors / Contributors
Global Information Author: Hammerson, G.
Last Updated: Apr 01, 1996
Provincial Information Author:
Last Updated:
   
References and Related Literature
American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
Baekken, B. T., J. O. Nybo, and G. A. Sonerud. 1987. Home range size of Hawk Owls: dependence on calculation method, number of tracking days, and number of plotted perches. Pp. 145-148 IN Nero, R.W., R. J. Clark, R. J. Knapton, and H. Hamre, eds. Biology and conservation of northern forest owls. USDA For. Serv. Gen. Tech. Rep. RM-142, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.
Bent, A. C. 1938. Life histories of North American birds of prey. Part 2. U.S. Nat. Mus. Bull. 170. 482 pp., 92 pls.
Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, et al. 1990b. The Birds of British Columbia Vol. 2: Nonpasserines: Diurnal Birds of Prey through Woodpeckers. Royal British Columbia Museum, Victoria, BC.
Clark, R. J., D. G. Smith, and L. H. Kelso. 1978. Working bibliography of owls of the world. National Wildlife Federation, Sci. & Tech. Ser. No. 1. 336 pp.
Eckert, Allan W. 1978. The Owls of North America. Weather-vane Books, New York. 278 pp.
Fisher, A.K. 1893. The hawks and owls of the United States in their relation to agriculture. Washington U.S. Dept. of Agriculture Bull. no. 6. 210 pp.
Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.
Johnsgard, P. 1988. North American owls: biology and natural history. Smithsonian Inst. Press. 336 pp.
Kirk, D. A., D. Hussell, and E. Dunn. 1995. Raptor population status and trends in Canada. Bird Trends (Canadian Wildlife Service) 4:2-9.
National Geographic Society (NGS). 1983. Field guide to the birds of North America. National Geographic Society, Washington, DC.
Nicholls, T. H., and M. R. Fuller. 1987. Owl telemetry techniques. Pages 294-301 IN R.W. Nero, R.J. Clark, R.J. Knapton, and R.H. Hamre, editors. Biology and conservation of northern forest owls. USDA Forest Service, Gen. Tech. Rep. RM-142.
Pendleton, B. A. G., B. A. Millsap, K. W. Cline, and D. M. Bird. 1987. Raptor management techniques manual. National Wildlife Federation, Sci. and Tech. Ser. No. 10. 420 pp.
Rohner, C., J. N. M. Smith, J. Stroman, M. Joyce, F. I. Doyle, and R. Boonstra. 1995. Northern hawk-owls in the Nearctic boreal forest: prey selection and population consequences of multiple prey cycles. Condor 97:208-220.
Smith, D.G. 1987b. Owl census techniques. Pages 304-307 in R.W. Nero, R.J. Clark, R.J. Knapton, and R.H. Hamre, editors. Biology and conservation of northern forest owls. USDA Forest Service, Gen. Tech. Rep. RM-142.
Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
Voous, K. H., and A. Cameron. 1989. Owls of the Northern Hemisphere. MIT Press, Cambridge, Massachusetts. 320 pp.
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 1996. Species Summary: Surnia ulula. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Oct 3, 2026).