Thomo has just claimed on another thread that the eggs of black-headed gulls are deliberately rendered infertile at Minsmere. I'd really like to know the truth of this as they, as well as avocets, are on the UK Amber List and Minsmere is the only black-headed gullery in Suffolk (to the best of my knowledge).
Our herring gulls are red listed birds. Think about that the next time you hear some flaming idiot calling for a cull of them.