Identification of gulls can be difficult as most go through several immature moults before attaining adult plumage. This is a Herring Gull in its third-winter plumage; the bill is yellow with a black tip, lacking the red gonys spot of the adult bird. Patterned beaks and red gonys spots may have evolved to focus the pecking response of chicks, especially when the chicks are relatively small at hatching in relation to their parents. Blackwaterfoot beach, Arran, Scotland, early May.