What distinguishing feature of the Xeme tail is rare among gull species?
Answer
Forked tail
The most distinguishing structural feature for field identification of the Sabine's Gull, *Xema sabini*, is its tail shape, which is forked or sometimes described as notched. This feature is extremely rare among the general family of gulls, shared almost exclusively with the Swallow-tailed Gull, although the latter is not closely related genetically. This unique tail structure, unlike the square or rounded tail often seen on other small gulls like the Bonaparte's Gull, serves as a critical identification clue when the bird's flight profile is visible.
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