• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

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: http://www.aerc.eu/DOCS/Bird_taxa_of_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.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	A2bd+3bd+4bd

Red List history

Year	Category	Criteria
2021	Vulnerable	A2bd+3bd+4bd
2020	Vulnerable	A2bd+3bd+4bd
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

Migratory status	full migrant	Forest dependency	does not normally occur in forest
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	38,100,000 km2	medium
Extent of Occurrence (non-breeding)	80,500,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	14000-28000 mature individuals	poor	estimated	2013
Population trend	decreasing	-	estimated	2011-2035
Rate of change over the past 10 years/3 generations (longer of the two periods)	30-49%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	30-49%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	30-49%	-	-	-
Generation length	7.77 years	-	-	-

Population justification: Partners in Flight Science Committee (2013) estimated the population 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). However, Potapov and Sale (2013) presented a 'Loose Boid’ method of estimating population size which gives far lower figures. They concluded that instead of being evenly distributed across the tundra, snowy owls could be found in seven different loose 'boids': very thinly distributed groups which move throughout given areas in line with conditions, especially 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). Satellite tracking projects in the Canadian Arctic and Norway have documented extensive individual movements, further suggesting that the population may have been overestimated in the past (R. Solheim and G. Gauthier in litt. 2017).

The European population is estimated at 1,200-2,700 pairs, which equates to 2,400-5,400 mature individuals (BirdLife International in prep.).

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.43.6% over 3 generations (c.24 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 25.3-30.1%. 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 – 43.6%. It should be noted that Snowy Owl populations do fluctuate (BirdLife International 2015) and so this may affect population trend estimates. Partners in Flight (2019) currently estimate a rate of annual decline of ~1.68%, which equates to a decline of ~33.4% over three generations. As such, 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	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Albania	extant	vagrant
Austria	extant	vagrant
Belarus	extant	vagrant
Belgium	extant	vagrant
Bermuda (to UK)	extant	vagrant
Canada	extant	native		yes	yes
China (mainland)	extant	native			yes
Croatia	extant	vagrant
Czechia	extant	vagrant			yes
Denmark	extant	vagrant			yes
Faroe Islands (to Denmark)	extant	vagrant
Finland	extant	native		yes	yes
France	extant	vagrant
Germany	extant	vagrant
Greenland (to Denmark)	extant	native		yes	yes
Hungary	extant	vagrant
Iceland	extant	native			yes
Iran, Islamic Republic of	extant	vagrant			yes
Ireland	extant	vagrant
Japan	extant	native			yes
Kazakhstan	extant	native			yes
Kyrgyzstan	extant	vagrant
Latvia	extant	native			yes
Luxembourg	extant	vagrant
Mongolia	extant	vagrant
Montenegro	extant	vagrant
Netherlands	extant	vagrant
North Korea	extant	vagrant
Norway	extant	native		yes	yes
Pakistan	extant	vagrant
Poland	extant	vagrant
Portugal	extant	vagrant
Russia	extant	native		yes	yes
Russia (Asian)	extant	native		yes	yes
Russia (Central Asian)	extant	native		yes	yes
Russia (European)	extant	native		yes	yes
Serbia	extant	vagrant
Slovakia	extant	vagrant			yes
South Korea	extant	vagrant
St Pierre and Miquelon (to France)	extant	native			yes	yes
Svalbard and Jan Mayen Islands (to Norway)	extant	native		yes
Sweden	extant	native		yes	yes
Turkmenistan	extant	vagrant
Ukraine	extant	vagrant			yes
United Kingdom	extant	native			yes
USA	extant	native		yes	yes

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 (Asian)	Gusikha river basin and lower Balakhnya river
Russia (Asian)	Kolyma delta
Russia (Asian)	Lower Nizhnyaya Taymyra river
Russia (Asian)	Preobrazheniya island
Russia (Asian)	Wrangel and Herald Islands
Russia (Central Asian)	Upper and Middle Yuribey
Russia (European)	Vaygach island
Sweden	Lake Tjålme – Valley of Lais

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Arable Land	suitable	non-breeding
Artificial/Terrestrial	Pastureland	suitable	resident
Artificial/Terrestrial	Urban Areas	marginal	non-breeding
Grassland	Tundra	major	resident
Marine Coastal/Supratidal	Coastal Sand Dunes	suitable	non-breeding
Marine Intertidal	Mud Flats and Salt Flats	suitable	resident
Wetlands (inland)	Bogs, Marshes, Swamps, Fens, Peatlands	suitable	resident
Wetlands (inland)	Permanent Saline, Brackish or Alkaline Marshes/Pools	suitable	resident
Altitude	0 - 300 m	Occasional altitudinal limits

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
		Stresses Species mortality
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Species mortality
Biological resource use	Hunting & trapping terrestrial animals - Unintentional effects (species is not the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Species mortality
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Ongoing		Whole (>90%)		Slow, Significant Declines		Medium Impact: 7
		Stresses Indirect ecosystem effects, Ecosystem degradation
Pollution	Agricultural & forestry effluents - Herbicides and pesticides	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species mortality
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion
Transportation & service corridors	Flight paths	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Unknown		Unknown
		Stresses Species mortality
Transportation & service corridors	Roads & railroads	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Unknown		Unknown
		Stresses Species mortality
Transportation & service corridors	Utility & service lines	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Unknown		Unknown
		Stresses Species mortality

Purpose	Scale
Food - human	subsistence, national
Other household goods	subsistence, national
Pets/display animals, horticulture	international

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Recommended citation
BirdLife International (2024) Species factsheet: Snowy Owl Bubo scandiacus. Downloaded from https://datazone.birdlife.org/species/factsheet/snowy-owl-bubo-scandiacus on 24/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 24/12/2024.