© A. Warr

Ring-billed Gull shares some similarities with  Common Gull but the size and proportions of Ring-billed Gull are more substantial, with a heavier and rather 'squarer' head-shape and a deeper, blunter and more parallel-sided bill. When seen well the appearance of adults is distinctive:  the mantle is paler grey than Common Gull, the bill is bright yellow or greenish-yellow with a conspicuous black band subterminally, and the iris is strikingly yellow. Immatures are somewhat less obvious and larger individuals need also to be distinguished from immature Herring Gull (e.g. 1W Ring-billed and 2W Herring can be confused by the unwary).