Strix nebulosa 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Strigiformes Strigidae

Scientific Name: Strix nebulosa
Species Authority: Forster, 1772
Regional Assessments:
Common Name(s):
English Great Grey Owl, Great Gray Owl
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2012-05-03
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Butchart, S., Ekstrom, J. & Ashpole, J
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.
Previously published Red List assessments:
2012 Least Concern (LC)
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Countries occurrence:
Belarus; Canada; China; Finland; Kazakhstan; Lithuania; Mongolia; Norway; Russian Federation; Sweden; Ukraine; United States
Regionally extinct:
Germany; Poland
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 19800000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 3200
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population is estimated to number approximately 190,000 individuals which equates to 127,000 mature individuals (Partners in Flight Science Committee 2013). The North American population is estimated at 90,000 individuals or 60,000 mature individuals (Partners in Flight Science Committee 2013). The European population is estimated at 1,900-7,500 pairs, which equates to 3,900-15,000 mature individuals (BirdLife International 2015). Europe forms approximately 13% of the global range, so a very preliminary estimate of the global population size is 30,000-115,000 mature individuals, although further validation of this estimate is needed. The population is precautionarily placed in the band 50,000-99,999 mature individuals but the actual population could be considerably larger.

Trend Justification:  The overall trend is likely to be increasing. This species has undergone a large and statistically significant increase over the last 40 years in North America (4900% increase over 40 years, equating to a 166% increase per decade; 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 is also estimated to be increasing (BirdLife International 2015).
Current Population Trend: Increasing
Additional data:
Number of mature individuals: 50000-99999 Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Threats [top]

Major Threat(s): The species is affected by global warming, which if it persists will continue to move the species’s range northwards (Hagemeijer and Blair 1997). Populations fluctuate in line with vole numbers (Cornulier et al. 2013). Locally, hunting may still be a threat (König 2008). It is also vulnerable to road traffic collisions and loss of habitat from forestry (Holt et al. 1999). Collisions with power lines and cables are also a threat. In North America timber harvesting, collisions with vehicles, strychnine poisoning of pocket gophers, disturbance at foraging habitats due to development of campsites, grazing, peat extraction and agriculture have all been identified as potential threats (Holt et al. 1999). The species is known to be vulnerable to West Nile Virus (Lopes et al. 2007).

Citation: BirdLife International. 2015. Strix nebulosa. The IUCN Red List of Threatened Species 2015: e.T22689118A80506228. . Downloaded on 29 November 2015.
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