Common terns (Sterna hirundo) as well as other tern species have own rituals which help better understand each other in complicated social life. One of them is exchange snack for copulation: male deliver a small fish or something the same tasty for his female and after that she became ready for copulation with him. This time male jumped on the back of female without any snack before, so he breaks the ritual and need to wait ca 3 minutes for the sex which take seconds normaly. Nioman river in Hrodna city, W Belarus 14-05-2022 Several pictures + story in Belarusian are here: https://birdwatch.by/gallery/harrier/rachnyya-krychki-18 Некалькі здымкаў і апісанне гісторыі пра капуляцыю рачных крычак тут: https://birdwatch.by/gallery/harrier/rachnyya-krychki-18