Taking photographs of birds flying is a perfect exercise in understanding the almost unpredictable interactions between birds and their environment. It is a subtle way to appreciate the patterns of behaviour of other beings, while we do not have any conception how they originated.
I always set my criteria first: first was to take a photograph at the moment when a seagull comes from behind the rock flying towards the sea.
The second was of birds settling for the evening and a late companion was joining them. I wanted that bird to be within a frame-like markings on the rock.