Slender-billed Gull

The slender-billed gull breeds in northeastern Siberia and migrates to the Indian subcontinent, Southeast Asia, the Philippines, and as far away as Australia in winter. It is occasionally seen in Asia and is often active in large groups. It is very rare in China.
When I saw this only one in Deyang, Sichuan, China last month, it was very active, sometimes grabbing food, sometimes happily playing in the water and bathing, and sometimes combing its feathers...