Snowy Owl Bubo scandiacus


Taxonomic note
Bubo scandiacus (del Hoyo and Collar 2014) was previously listed as B. scandiaca.

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. and Simmons, K.E.L. (eds). 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. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - A2bd+3bd+4bd

Red List history
Year Category Criteria
2017 Vulnerable A2bd+3bd+4bd
2016 Least Concern
2012 Least Concern
2009 Least Concern
2008 Least Concern
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern
Species attributes

Migratory status full migrant Forest dependency Does not normally occur in forest
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 38,100,000 medium
Extent of Occurrence non-breeding (km2) 80,500,000 medium
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 28000 poor estimated 2013
Population trend Decreasing estimated -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 30-49 - - -
Decline (10 years/3 generation past and future) 30-49 - - -
Number of subpopulations - - -
Largest subpopulations - - -
Generation length (yrs) 12.1 - - -

Population justification: The population size was estimated to number approximately 200,000 individuals (Partners in Flight Science Committee 2013) (although there is some uncertainty over whether this refers to individuals or mature individuals), but recently, alternative methodologies have been presented which give far lower figures. 

Potapov and Sale (2013) presented a ‘Loose Boid’ method of estimating population size. They concluded that instead of being evenly distributed across the tundra, snowy owls could be found in seven different loose boids or very thinly distributed groups which may move throughout given areas in line with conditions; in particular food availability. The largest of these boids was suggested to be in central northern Canada and could contain 4,000 pairs. In total, they estimated that, on average, each boid may contain 2,000 pairs and so the global population size would be c.14,000 pairs or 28,000 mature individuals, which fits with a maximal estimate of 14,000 females suggested by DNA analyses by Marthinsen et al. (2009). However, they also suggested that the population size could be as low as 7,000-8,000 pairs (Potapov and Sale 2013).

The European population is estimated at 700-2,300 pairs, which equates to 1,400-4,600 mature individuals (BirdLife International 2015).

Trend justification:

High rates of population decline have been reported in at least the American and Canadian part of its range, with Rosenberg et al. (2016) estimating a 64% decline in U.S.A. and Canada between 1970 and 2014; with an estimated population in these two countries of <30,000 individuals. Extrapolating backwards this would equate to a decline of c.58% over 3 generations (c.36 years) in the population in these countries. 

This trend data can then be used in conjunction with Potapov and Sale’s (2013) ‘Loose Boids’. By sub-dividing the global population into these thinly distributed groups and assuming 4,000 pairs are found in the central northern Canadian Boid, this would then mean that on average c.1,667 pairs are found in each other grouping. One of the other 6 boids proposed by Potapov and Sale (2013) is restricted to North America [on Wrangel Island] and one more may move into North America [ranging from the Indrigirka River in Russia to Victoria Island in Canada]. Therefore, there may be between 5,667 and 7,333 pairs in North America at a given time; equating to 6,667-8,333 pairs outside of this range. Taking a very crude view that declines have only occurred in North America, and extrapolating backwards, the population estimates for this region would equate to global population declines over the past 3 generations in the range of 35.7-41.8%. This is not the case though, as the Snowy Owl is known to have declined in the Western Palearctic (e.g. Portenko 1972; Solheim 1994, 2004; I. J. Øien in litt. 2014; T. Lehtiniemi in litt. 2017), and climate change will be likely having global impacts on this species rather than local impacts. Therefore the global decline over three generations may in fact be more similar to that for North America alone – 58%. It should be noted that Snowy Owl populations do fluctuate (BirdLife International 2015) and so this may affect population trend estimates, but given the estimates presented, and the potential for threats to continue into the future then this species is likely to be undergoing global declines of 30-49% in three generations, or possibly even higher. 

Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Albania V Extant
Austria V Extant
Belarus V Extant
Belgium V Extant
Bermuda (to UK) V Extant
Canada N Extant Yes Yes
China (mainland) N Extant Yes
Croatia V Extant
Czech Republic V Extant Yes
Denmark V Extant Yes
Faroe Islands (to Denmark) N Extant
Finland N Extant Yes Yes
France V Extant
Germany V Extant
Greenland (to Denmark) N Extant Yes Yes
Hungary V Extant
Iceland N Extant Yes
Iran, Islamic Republic of V Extant Yes
Ireland V Extant
Japan N Extant Yes
Kazakhstan N Extant Yes
Kyrgyzstan V Extant
Latvia N Extant Yes
Luxembourg V Extant
Mongolia V Extant
Montenegro V Extant
Netherlands V Extant
North Korea V Extant
Norway N Extant Yes Yes
Pakistan V Extant
Poland V Extant
Portugal V Extant
Russia N Extant Yes Yes
Russia (Asian) N Extant Yes Yes
Russia (Central Asian) N Extant Yes Yes
Russia (European) N Extant Yes Yes
Serbia V Extant
Slovakia V Extant Yes
South Korea V Extant
St Pierre and Miquelon (to France) N Extant Yes Yes
Svalbard and Jan Mayen Islands (to Norway) N Extant Yes
Sweden N Extant Yes Yes
Turkmenistan V Extant
Ukraine V Extant Yes
United Kingdom N Extant Yes
USA N Extant Yes Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Finland Käsivarsi fjelds
Greenland (to Denmark) South coast of Germania Land, and Slaedelandet
Greenland (to Denmark) Stordal-Moskusoksefjord-Badlanddal-Loch Fyne-Myggbukta
Norway Varanger Peninsula
Russia (Central Asian) Upper and Middle Yuribey
Russia (European) Vaygach island
Sweden Lake Tjålme – Valley of Lais

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Pastureland suitable breeding
Artificial/Terrestrial Pastureland suitable non-breeding
Grassland Tundra major breeding
Grassland Tundra major non-breeding
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable breeding
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable non-breeding
Wetlands (inland) Permanent Saline, Brackish or Alkaline Marshes/Pools suitable breeding
Wetlands (inland) Permanent Saline, Brackish or Alkaline Marshes/Pools suitable non-breeding
Altitude 0 - 300 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Fishing & harvesting aquatic resources - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Ongoing Majority (50-90%) Unknown Unknown
Species mortality
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Species mortality
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Ongoing Whole (>90%) Rapid Declines High Impact: 8
Indirect ecosystem effects, Ecosystem degradation
Transportation & service corridors Flight paths Timing Scope Severity Impact
Ongoing Majority (50-90%) Unknown Unknown
Species mortality
Transportation & service corridors Roads & railroads Timing Scope Severity Impact
Ongoing Majority (50-90%) Unknown Unknown
Species mortality
Transportation & service corridors Utility & service lines Timing Scope Severity Impact
Ongoing Majority (50-90%) Unknown Unknown
Species mortality

Purpose Primary form used Life stage used Source Scale Level Timing
Food - human - - Non-trivial Recent
Other household goods - - Non-trivial Recent
Pets/display animals, horticulture - - International Non-trivial Recent

Recommended citation
BirdLife International (2017) Species factsheet: Bubo scandiacus. Downloaded from on 17/12/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from on 17/12/2017.