Usually the first indication of a nosey seagull is a useless throwaway comment about what you are looking at...
they can also be identified by the tilting of their head that catches your eye...then when you turn round, their stupid big fucking beak is almost touching your face.
They also have a nasty habit of picking up and reading printouts from a printer, that clearly do not belong to them.
They also tend to have stupid names like Roger.
Jeff: "Fuck off you big Nosey Seagull cunt" (the prefix and suffix used here are not always required but make it sound awesome.)
Alternative versions can be used when talking to a nosey seagull that happens to be your boss:
Roger the nosey boss seagull: "I see you're looking at the old interweb there?"
Jeff: "Bad Nosey Seagull!" (you can then either repeat this or add "cunt" depending on how much you like your job)