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

Taxonomic note

Sittiparus varius, S. owstoni, S. olivaceus and S. castaneoventris (del Hoyo and Collar 2016) were previously lumped as Parus varius following Sibley and Monroe (1990, 1993).

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	B1ab(ii,iii,v)+2ab(ii,iii,v)	B1ab(ii,iii,v)+2ab(ii,iii,v)

Red List history

Year	Category	Criteria
2017	Endangered	B1ab(ii,iii,v)+2ab(ii,iii,v)
2016	Near Threatened	C2a(i)
2012	Not Recognised
2008	Not Recognised
2004	Not Recognised
2000	Not Recognised
1994	Not Recognised
1988	Not Recognised

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	1,100 km2	medium
Area of Occupancy (breeding/resident)	33 km2
Number of locations	2-5	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	2900-3600 mature individuals	good	estimated	2011
Population trend	decreasing	-	suspected	-
Generation length	4.2 years	-	-	-
Number of subpopulations	3	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The population has been estimated at 4,425-5,286 individuals (Fujita et al. 2011), which is considered equivalent to 2,900-3,600 mature individuals. Estimates for the three islands were 1.953-2,285 individuals on Miyake-jima, 1,077-1,453 individuals on Mikura-jima and 1,394-1,548 individuals on Hachijo-jima (Fujita et al. 2011), equivalent to 1,300-1,550, 700-1,000 and 900-1050 mature individuals respectively.

Trend justification: Deforestation rates from Ł. Tracewski (unpublished data following Tracewski et al. [2016]) suggest that the species has lost c.10.9% of suitable habitat over the past 3 generations (c.12.5 years), which is believed to be causing a population decline.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Japan	extant	native	yes

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Rural Gardens	suitable	resident
Forest	Temperate	major	resident
Altitude		Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Wood & pulp plantations - Agro-industry plantations	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation
Geological events	Volcanoes	Timing		Scope		Severity		Impact
		Future		Majority (50-90%)		Rapid Declines		Low Impact: 5
		Stresses Indirect ecosystem effects, Species disturbance, Ecosystem degradation, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Felis catus	Timing		Scope		Severity		Impact
		Ongoing						Low Impact: 3
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Problematic native species/diseases - Corvus macrorhynchos	Timing		Scope		Severity		Impact
		Ongoing						Low Impact: 3
		Stresses Species mortality
Residential & commercial development	Tourism & recreation areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Transportation & service corridors	Roads & railroads	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion

Purpose	Scale
Pets/display animals, horticulture	international

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Recommended citation
BirdLife International (2024) Species factsheet: Izu Tit Sittiparus owstoni. Downloaded from https://datazone.birdlife.org/species/factsheet/izu-tit-sittiparus-owstoni on 26/11/2024.
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 26/11/2024.