• 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
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 (km2)	18,400,000	medium
Extent of Occurrence non-breeding (km2)	30,100,000	medium
Number of locations		-
Severely Fragmented		-

	Value	Data quality	Derivation	Year of estimate
No. of mature individuals		poor	estimated	1996
Population trend	Decreasing		suspected	-
Decline (3 years/1 generation past)		-	-	-
Decline (5 years/1 generation past)		-	-	-
Decline (10 years/1 generation past)		-	-	-
Decline (10 years/3 generation future)		-	-	-
Decline (10 years/3 generation past and future)		-	-	-
Number of subpopulations		-	-	-
Percentage in largest subpopulation		-	-	-
Generation length (yrs)	8	-	-	-

Population justification: The global population is estimated to number > c.1,300,000 individuals (del Hoyo et al. 1996), while national population estimates include: < c.1,000 wintering individuals in Korea; c.10,000-1 million breeding pairs c.1,000-10,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs in Russia (Brazil 2009).

Trend justification: The population is suspected to be in decline owing to bycatch, predation by invasive species and climate change.

Country/Territory	Occurrence status	Presence	Resident	Breeding	Non-breeding	Passage
Canada	N	Extant		Yes
China (mainland)	N	Extant	Yes
Japan	N	Extant	Yes
Mexico	N	Extant	Yes
North Korea	N	Extant		Yes
Russia	N	Extant	Yes
Russia (Asian)	N	Extant	Yes
South Korea	N	Extant	Yes
USA	N	Extant		Yes

Country/Territory	IBA Name
Japan	Teuri island
Japan	Yururi and Moyururi islets
Japan	Matsumae islets
Russia (Asian)	Kuril islands (between Urup and Paramushir)
Russia (Asian)	Tyuleniy Island
Canada	Scott Island Group
Canada	Duke of Edinburgh Ecological Reserve
Canada	Anthony Island
Canada	Englefield Bay Islands
Canada	Sidney Channel
Canada	Cleland Island and Southeast Clayoquot Sound
Canada	Amphitrite and Swiftsure Banks
Canada	Smith Sound Islets
Canada	Moore and Byers Islands and Banks
Canada	Lucy Islands
Canada	Kunghit Island and Luxana Bay
Canada	Skincuttle Inlet Islands
Canada	Cumshewa Inlet north to Sheldens Bay
Russia (Asian)	Kuril islands (between Urup and Paramushir) - Marine
Japan	Northern Hokkaido - Marine
Japan	Sanriku coast and Matsumaekojima - Marine
Russia (Asian)	Aniva bay / Esashi, Menashidomari / Teurito island - Marine
USA	Outer Islands Marine
USA	Forrester Island Colonies
USA	Castle Rock
USA	Olympic Continental Shelf
USA	Farallon Islands
USA	Point Reyes - Outer
USA	Trinidad Complex
Russia (Asian)	Lesser Kuril Ridge and Kunashir Island
Japan	Eastern Hokkaido - Marine

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Grassland	Temperate	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	0 - 200 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Biological resource use	Fishing & harvesting aquatic resources - Unintentional effects: (large scale) [harvest]	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		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Indirect ecosystem effects, Ecosystem degradation, Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Named species	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species disturbance, Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Procyon lotor	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species disturbance, Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Vulpes lagopus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Indirect ecosystem effects, Reduced reproductive success, Species mortality
Pollution	Industrial & military effluents - Oil spills	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Unknown		Unknown
		Stresses Reduced reproductive success

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

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Recommended citation
BirdLife International (2022) Species factsheet: Cerorhinca monocerata. Downloaded from http://www.birdlife.org on 26/06/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/06/2022.