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Location Japan, Chiba,Tokyo
Central coordinates 139o 53.00' East  35o 36.00' North
IBA criteria A4i, A4iii
Area 16,000 ha
Altitude 0 - 5m
Year of IBA assessment 2004

Wild Bird Society of Japan

Site description Since Tokyo Bay had sandy shallows for a good distance from the shore, its reclamation has been carried out. The reclaimed ground was once utilized for factories, but then they have been replaced by office buildings and high rise residences as a result of redevelopment. A campaign to conserve the few natural tidal flats including Sanbanse has been set up. The tidal flats are in the inner Tokyo Bay and include the Tamagawa river estuary, Sanmaisu (Tokyo), Sanbanse (Chiba), Shiohama (Chiba) and Yatsu-kigata (Chiba).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Greater Scaup Aythya marila winter  2004  present  A4i  Least Concern 
Great Cormorant Phalacrocorax carbo winter  2004  present  A4i  Least Concern 
Grey Plover Pluvialis squatarola passage  2004  present  A4i  Least Concern 
Grey-tailed Tattler Tringa brevipes passage  2004  present  A4i  Near Threatened 
Whimbrel Numenius phaeopus passage  2004  present  A4i  Least Concern 
Ruddy Turnstone Arenaria interpres passage  2004  present  A4i  Least Concern 
Sanderling Calidris alba passage  2004  present  A4i  Least Concern 
Dunlin Calidris alpina passage  2004  present  A4i  Least Concern 
A4iii Species group - waterbirds winter  2004  min 20,000 individuals  A4iii   

IBA Monitoring

2010 medium not assessed low
Poor - based on little, or potentially unreliable/unrepresentative, data

Transportation and service corridors roads and railroads likely in short term (within 4 years) some of area/population (10-49%) slow but significant deterioration medium

Most of site (50-90%) covered (including the most critical parts for important bird species)  A management plan exists but it is out of date or not comprehensive  Unknown  low 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Yatsu-higata Wetlands of International Importance (Ramsar) 40 protected area contained by site 40  


IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Estuarine waters  -

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Recommended citation  BirdLife International (2015) Important Bird Areas factsheet: Inner Tokyo bay. Downloaded from on 05/10/2015

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