Swans in Hyo-ko, cherry blossoms, and Gozu mountain range with remaining snow
Flying for commuting
Hyo-ko in a fine clear day
Hyo-ko at sunrise


  • Country: 
  • Site number: 
  • Area: 
    24 ha
  • Designation date: 
  • Coordinates: 
    37°50'N 139°14'E
Materials presented on this website, particularly maps and territorial information, are as-is and as-available based on available data and do not imply the expression of any opinion whatsoever on the part of the Secretariat of the Ramsar Convention concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries.


The Site is a small wetland consisting of man-made ponds that were constructed initially for irrigation purposes in Agano City. At present, these ponds serve as habitats for various plants and animals including threatened species such as Japanese crucian carp (Carassius cuvieri) and common pochard (Aythya ferina). At least 117 bird species have been recorded here, among which many are migratory and use the Site as non-breeding habitats. The Site is particularly important for the conservation of tundra swan (Cygnus columbianus), as over 3,000 individuals migrate here every year. It also shelters about 3% of the regional population of northern pintail (Anas acuta). Hunting is prohibited at the Site and local residents are involved in its conservation. Dredging and invasive species are major threats, but a management plan is being implemented. The Site has also been designated as a Special Protection Area within the Hyo-ko National Wild Protection Area.

Administrative region: 
Agano City, Niigata Prefecture

  • National legal designation: 
    • Natural monument - Suibara's swan landing zone
    • Wildlife refuge - Hyo-ko Specail Protection Area of the Hyo-ko National Wildlife Protection Area,
  • Last publication date: 


Ramsar Information Sheet (RIS)