Little Tern
Sternula albifrons

Little Terns can be found in coastal areas and rivers in many parts of the world, but are far less numerous than a few centuries ago, mainly due to pollution, habitat loss and disturbance while breeding. Small numbers of these birds pass through Japan on migration, but a few do breed in the country. They are one of the smallest terns at 22-28 cm in length and a wingspan of 47-55 cm. They are superficially similar to the equally-small Fairy Tern, which occurs in the south-west Pacific.
 

1: Kasai Rinken Koen, Tokyo, 23/05/2012.