ID tips & tricks
Lesser Black-backed and Great Black-backed Gulls can be quickly separated on bill depth and the gonys
BILL SIZE AND SHAPE
Gulls can be very confusing and difficult birds to identify, often requiring practice and experience to identify with confidence. Some difficult species pairings require an assessment of a whole ‘suite’ of features to properly nail. One key component of any assessment of gulls is the size and shape of the bill. A smaller bill generally means a smaller bird. For instance, the potentially confusing (for the inexperienced) pairing of Herring and Common Gull can simply and immediately be separated by the Herring’s much larger, longer and thicker bill (and the Common’s correspondingly smaller, finer bill). Similarly Lesser Black-backed and Great Black-backed Gulls can be quickly separated on bill depth and the gonys (the pointy bit on the underside of the bill). Bill structure and shape is also used by more experienced gull-watchers when separating Caspian and Yellow-legged or Herring Gulls. Don’t neglect the front end!
Great Black Backed Gull
Lesser Black-backed Gull