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

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. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2020	Least Concern
2018	Least Concern
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	not a migrant	Forest dependency	does not normally occur in forest
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	4,510,000 km2
Extent of Occurrence (non-breeding)	5,950,000 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	20000000 mature individuals	poor	estimated	2013
Population trend	decreasing	-	suspected	-
Generation length	7.2 years	-	-	-

Population justification: The global population is estimated to number 20 million mature individuals (Partners in Flight 2019).

Trend justification: The population is suspected to be in decline due to predation by invasive species and loss of access to prey resources due to climate change-driven trophic shifts.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Canada	extant	vagrant			yes
Japan	extant	native			yes
Russia	extant	native	yes	yes	yes
Russia (Asian)	extant	native	yes	yes	yes
USA	extant	native	yes	yes	yes

Country/Territory	IBA Name
Russia (Asian)	Iony Island
Russia (Asian)	Ratmanova Island
Russia (Asian)	Yamskiye Islands
USA	Diomede Islands Colonies
USA	Gareloi Island Colony
USA	Gareloi Island Marine
USA	Kiska Island Colonies
USA	Kiska Island Marine
USA	Northwest Cape Colony
USA	Savoonga Colonies
USA	Segula & Davidof Islands Colonies
USA	Southwest Cape Colonies
USA	St George Island Colony
USA	St Matthew & Hall Islands Colonies

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Marine Coastal/Supratidal	Sea Cliffs and Rocky Offshore Islands	major	breeding
Marine Intertidal	Rocky Shoreline	major	breeding
Marine Intertidal	Tidepools	major	breeding
Marine Neritic	Macroalgal/Kelp	major	resident
Marine Neritic	Pelagic	major	resident
Marine Neritic	Seagrass (Submerged)	major	resident
Marine Neritic	Subtidal Loose Rock/pebble/gravel	major	resident
Marine Neritic	Subtidal Rock and Rocky Reefs	major	resident
Marine Neritic	Subtidal Sandy	major	resident
Marine Neritic	Subtidal Sandy-Mud	major	resident
Marine Oceanic	Epipelagic (0-200m)	suitable	resident
Marine Oceanic	Mesopelagic (200-1000m)	suitable	resident
Altitude		Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Unknown		Unknown
		Stresses Indirect ecosystem effects, Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus norvegicus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Vulpes vulpes	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Reduced reproductive success, Species mortality

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

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Recommended citation
BirdLife International (2024) Species factsheet: Least Auklet Aethia pusilla. Downloaded from https://datazone.birdlife.org/species/factsheet/least-auklet-aethia-pusilla on 23/11/2024.
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 23/11/2024.