There were several species of Tern at Mai Po. Commonest were Gull-billed Terns. This is a species I’ve only ever seen once in Japan. There were also smaller numbers of Caspian Tern and Whiskered Tern: 2 other very scarce birds in Hokkaido (I7ve seen 2 of each over the last 20 years). Grey skies and heavy rain were not helpful for BIF shots of course.