A bird species Larus ridibundus, is a familiar bird in Japan and probably all over the world.  I was a little surprised to hear that its English name was Black-headed Gull, because it is a white bird that is usually seen only in winter in Japan.

Ornithologists used to conduct surveys to attach rings to the legs, and I often saw black-headed gulls with letters on the rings on their legs.

In January 2017, I was very happy when I found one which I saw at the same place two years ago on the shores of Lake Biwa in Otsu City, Shiga Prefecture.

However, it seems that the survey of leg rings has not done recently. I do not see any with rings at all in recent years.