• 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
-	-	C2a(ii)

Red List history

Year	Category	Criteria
2018	Vulnerable	C2a(ii)
2016	Vulnerable	A2cde+3cde+4cde;C2a(ii)
2012	Vulnerable	A2cde+3cde+4cde;C2a(ii)
2010	Vulnerable	A2c,d,e; A3c,d,e; A4c,d,e; C2a(ii)
2008	Vulnerable	A2d,e; A3d,e; A4d,e; C2a(ii)
2007	Vulnerable
2005	Vulnerable
2004	Vulnerable
2000	Vulnerable
1996	Vulnerable
1994	Vulnerable
1988	Threatened

Migratory status	not a migrant	Forest dependency	Does not normally occur in forest
Land mass type	Land-mass type - shelf island	Average mass	-

	Estimate	Data quality
Extent of Occurrence breeding/resident (km2)	1,310,000	medium
Extent of Occurrence non-breeding (km2)	2,580,000	medium
Extent of Occurrence breeding/resident (km2)	110	medium
Number of locations	11-100	-
Severely Fragmented		-

	Value	Data quality	Derivation	Year of estimate
No. of mature individuals	5200-9400	medium	estimated	2000
Population trend	Decreasing	poor	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	1	-	-	-
Percentage in largest subpopulation	100	-	-	-
Generation length (yrs)	12.1	-	-	-

Population justification: By 2015, 38 colonies (current and historical) were reported, with a total estimated population of 2,600-4,700 pairs (Otsuki and Nakamura 2016), equating to around 5,200-9,400 mature individuals. National population sizes have been estimated at <100 breeding pairs and c.50-1,000 individuals on migration in Korea and c.100-10,000 breeding pairs and c.50-1,000 wintering individuals in Japan (Brazil 2009).

Trend justification: Populations are thought to be declining rapidly through the combined impact of bycatch mortality and predation by invasive species.

Country/Territory	Occurrence status	Presence	Resident	Breeding	Non-breeding	Passage
Japan	N	Extant		Yes
Russia	N	Extant	Yes
Russia (Asian)	N	Extant	Yes
South Korea	N	Extant		Yes
Taiwan, China	V	Extant			Yes

Country/Territory	IBA Name
Japan	Niijima and Shikinejima Islands
Japan	Kozushima island
Japan	Miyakejima island
Japan	Mikurajima island
Japan	Hachijojima island
Japan	Torishima island
Japan	Kanmurijima and Kutsujima islets
Japan	Seinan islands
Japan	Okinoshima and Koyajima islets
Japan	Nanatsujima islets
Japan	Kii Nagashima islets
Japan	Tsukuejima islets
Japan	Eboshijima islet
Japan	Danjo islands
Japan	Birojima islet
South Korea	Kukul-do island
South Korea	Chilbal-do island
South Korea	Chilbal-do island - Marine
South Korea	Kukul-do island - Marine
Japan	Kozushima island / Kozushima island (Onbasejima) - Marine
Japan	Miyakejima island - Marine
Japan	Mikurajima island - Marine
Japan	Hachijojima island - Marine
Japan	Torishima island - Marine
Japan	Kanmurijima and Kutsujima islets - Marine
Japan	Seinan islands - Marine
Japan	Kyushu seas (north and west)
Japan	Nanatsujima islets - Marine
Japan	Kii Nagashima islets - Marine
Japan	Danjo islands - Marine
Japan	Birojima islet - Marine
Japan	Mikomotojima island
Japan	Mikomotojima island-Marine
Japan	Kii Nagashima islets-Marine
Japan	Okinoshima and Koyajima islands - Marine
Japan	Tsukuejima islets - Marine
Japan	Fumishima Islet and Oki Islands - Marine
Japan	Eboshijima islet - Marine
Japan	Northern Izu Islands - Marine

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Marine Coastal/Supratidal	Sea Cliffs and Rocky Offshore Islands	major	breeding
Marine Neritic	Pelagic	suitable	resident
Marine Oceanic	Epipelagic (0-200m)	suitable	non-breeding
Altitude		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		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Species mortality
Biological resource use	Fishing & harvesting aquatic resources - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Species mortality
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Majority (50-90%)		Slow, Significant Declines		Past Impact
		Stresses Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Felis catus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus rattus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Rapid Declines		Medium Impact: 6
		Stresses Reduced reproductive success, Species mortality
Pollution	Industrial & military effluents - Oil spills	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Species mortality

Purpose	Primary form used	Life stage used	Source	Scale	Level	Timing
Food - human	-	-			Non-trivial	Recent

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Recommended citation
BirdLife International (2023) Species factsheet: Synthliboramphus wumizusume. Downloaded from http://www.birdlife.org on 08/02/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/02/2023.