Funny you should put them up, I just had an experience today with black headed gulls that made me think "I wish Ian was here with his camera!" After my hospital appointment we got a mucky Ds and we sitting in the car in the car park eating it. There were a load of quite bold black headed gulls around. I opened my window and held out some fries for them. They were flying in and hovering there, taking the fries out of my fingers, would have made some great photos!