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Northern Hawk-owl Surnia ulula

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be fluctuating, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: # _the_WP15.xls#.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

Population justification
The global population is estimated to number > c.120,000 individuals which equates to 80,000 mature individuals (Partners in Flight Science Committee 2013). The North American population is estimated at approximately 60,000 individuals which equates to 40,000 mature individuals (Partners in Flight Science Committee 2013). The European population is estimated at 10,400-53,900 pairs, which equates to 20,800-108,000 mature individuals (BirdLife International 2015). Europe forms approximately 13% of the global range, so a very preliminary estimate of the global population size is 160,000-831,000 mature individuals, although further validation of this estimate is needed. The population is precautionarily placed in the band 100,000-499,999 mature individuals however the actual population could be larger.

Trend justification
The overall trend is likely to be fluctuating. This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). Note, however, that these surveys cover less than 50% of the species's range in North America. In Europe the population size trend is unknown (BirdLife International 2015).

The species is dependent on rodent populations and numbers fluctuate with the abundance of small rodents. In Finland, the population has declined since 19th century, as a result of disappearance of hollow trees and through human persecution (Holt et al. 2013). In North America, forestry practices and fire suppression may reduce suitable habitat (Holt et al. 2013). The species is known to be vulnerable to West Nile Virus (Komar 2003).

BirdLife International. 2015. European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg.

Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

Holt, D.W., Berkley, R., Deppe, C., Enríquez Rocha, P., Petersen, J.L., Rangel Salazar, J.L., Segars, K.P., Wood, K.L. and Christie, D.A. 2013. Northern Hawk-owl (Surnia ulula). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds), Handbook of the Birds of the World Alive, Lynx Edicions, Barcelona.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: (Accessed: 19 November 2015).

Komar, N. 2003. West Nile virus: epidemiology and ecology in North America. Advances in Virus Research 61: 185-234.

Partners in Flight Science Committee. 2013. Population Estimates Database, version 2013. Available at: (Accessed: 09/07/2015).

Rich, T.D.; Beardmore, C.J.; Berlanga, H.; Blancher, P.J.; Bradstreet, M.S.W.; Butcher, G.S.; Demarest, D.W.; Dunn, E.H.; Hunter, W.C.; Inigo-Elias, E.E.; Martell, A.M.; Panjabi, A.O.; Pashley, D.N.; Rosenberg, K.V.; Rustay, C.M.; Wendt, J.S.; Will, T.C. 2004. Partners in flight: North American landbird conservation plan. Cornell Lab of Ornithology, Ithaca, NY.

Further web sources of information
Detailed regional assessment and species account from the European Red List of Birds (BirdLife International, 2015)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Butchart, S. & Ashpole, J

IUCN Red List evaluators
Butchart, S. & Symes, A.

Recommended citation
BirdLife International (2015) Species factsheet: Surnia ulula. Downloaded from on 29/11/2015. Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from on 29/11/2015.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Least Concern
Family Strigidae (Typical Owls)
Species name author (Linnaeus, 1758)
Population size 100000-499999 mature individuals
Population trend Stable
Distribution size (breeding/resident) 21,100,000 km2
Country endemic? No
Links to further information
- Additional Information on this species
- 2015 European Red List assessment