This seagull seems to be aware of humans standing nearby, and it definitely does not mind. In fact, the bird barks like a dog, trying to say something important, like "please, keep out", or "this is my place now".
According to the author, the seagull had decided to nest there and raise her chick. The unusual bird even started barking when he asked it not to screech anymore, and opt for something less annoying than dreadful seagull screams. Well, it appears as if it really worked!