Challenging to distinguish from Herring and Yellow-legged gulls without closely examining plumage characteristics. Slender-legged, slender-billed birds may be conspicuous due to their appearance. Other helpful traits are a flattened crown, relatively small dark eyes, and a typically unstreaked skull. Adult wingtip (primary) feathers have long white tongues extending into the black tips. Pale underwings are predominant on juveniles.