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The site was identified as important in 2004 because it was regularly supporting significant populations of the species listed below, meeting ('triggering') IBA criteria.

Populations meeting IBA criteria ('trigger species') at the site:

Species	Red List1	Season	Year(s)	Size	IBA criteria
Black-tailed Gull Larus crassirostris	LC	resident	2003	present	A4i
A4iii Species group - seabirds	n/a	breeding	2003	min 10,000 breeding pairs	A4iii

1. The current IUCN Red List category. The category at the time of the IBA criteria assessment (2004) may differ.

Ideally the conservation status of the IBA will have been checked regularly since the site was first identified in 2004. The most recent assessment (2015) is shown below.

State (condition of the trigger species' habitats)
Habitat	Quantity (% remaining)	Quality (% carrying capacity)	Result
Marine Coastal/Supratidal	good (> 90%)	very poor (< 40%)	very unfavourable

Pressure (threats to the trigger species and/or their habitats)
Threat	Timing	Scope	Severity	Result
Invasive and other problematic species and genes	happening now	some of area/population (10-49%)	very rapid to severe deterioration	high
Natural system modifications	happening now	majority/most of area/population (50-90%)	moderate to rapid deterioration	high
Climate change and severe weather	happening now	majority/most of area/population (50-90%)	slow but significant deterioration	high
Pollution	happening now	majority/most of area/population (50-90%)	slow but significant deterioration	high
Energy production and mining	likely in short term (within 4 years)	some of area/population (10-49%)	moderate to rapid deterioration	medium
Geological events	likely in long term (beyond 4 years)	some of area/population (10-49%)	slow but significant deterioration	medium
Human intrusions and disturbance	happening now	some of area/population (10-49%)	slow but significant deterioration	medium

Response (conservation actions taken for the trigger species and/or their habitats)
Protected areas	Management plan	Other action	Result
Whole area of site (>90%) covered by appropriate conservation designation	No management plan exists but the management planning process has begun	Very little or no conservation action taking place	low

Year	Protected Area	Designation	% overlap with IBA
1963	Chokai	国定公園	100
1972	Tobishima	都道府県指定鳥獣保護区	93
2003	Common fishery right area(Yamagata)	共同漁業権区域	7

Habitat1	Habitat detail	% of IBA
Marine Coastal/Supratidal		-

1. IUCN Habitat classification.

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Tobishima and Oshakujima islands (Japan). Downloaded from https://datazone.birdlife.org/site/factsheet/tobishima-and-oshakujima-islands-iba-japan on 23/11/2024.