Seagull chases ospray
In this one you can see some part of how those familiar seagulls have "owned" part of the lake during nesting season.
First issue is that they formed with some other birds a network of alarms. When someone sees a dangerous bird or other animal they sound an alarm and many joins in. And you can't miss the danger.
Then they attack against that danger. Sometime just one or two birds, sometime many of them.
And they defend "their area" very aggressively even against ospray that eats fish. Of course also Eagles and hawks get similar treatment.
Hope you enjoy.