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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
Greater Scaup Aythya marila	LC	winter	2003	present	A4i
Great Cormorant Phalacrocorax carbo	LC	winter	2003	present	A4i
Grey Plover Pluvialis squatarola	VU	winter	2003	present	A4i
Whimbrel Numenius phaeopus	LC	passage	2003	present	A4i
Ruddy Turnstone Arenaria interpres	NT	passage	2003	present	A4i
Sanderling Calidris alba	LC	passage	2003	present	A4i
Dunlin Calidris alpina	NT	winter	2003	present	A4i
Grey-tailed Tattler Tringa brevipes	LC	passage	2003	present	A4i
A4iii Species group - waterbirds	n/a	winter	2003	min 20,000 individuals	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 Intertidal	good (> 90%)	poor (40-69%)	unfavourable

Pressure (threats to the trigger species and/or their habitats)
Threat	Timing	Scope	Severity	Result
Human intrusions and disturbance	happening now	some of area/population (10-49%)	very rapid to severe deterioration	high

Response (conservation actions taken for the trigger species and/or their habitats)
Protected areas	Management plan	Other action	Result
Little/none of site covered (<10%)	No management planning has taken place	Substantive conservation measures are being implemented but these are not comprehensive and are limited by resources and capacity	low

Year	Protected Area	Designation	% overlap with IBA
1974	Tamagawa	都道府県指定鳥獣保護区	1
1979	Gyotoku	都道府県指定鳥獣保護区	<1
1987	Tokyowan	都道府県指定鳥獣保護区	20
1988	Yatsu	国指定鳥獣保護区	<1
1993	Yatsu-higata	Ramsar Site, Wetland of International Importance	<1
2003	Common fishery right area(Chiba)	共同漁業権区域	10
2006	Tamagawa	都道府県指定鳥獣保護区	1

Habitat1	Habitat detail	% of IBA
Marine Intertidal		major (>10)
Marine Neritic		major (>10)

1. IUCN Habitat classification.

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Inner Tokyo bay (Japan). Downloaded from https://datazone.birdlife.org/site/factsheet/inner-tokyo-bay-iba-japan on 23/11/2024.