What pattern on the wings creates a noticeable dark triangle at the wingtip in flight?
Answer
The contrast between black outer primaries and white inner primaries/secondaries
The wings of the Sabine’s Gull exhibit a spectacular tricolored pattern that is most evident in flight. Specifically, the outermost primary flight feathers are black, while the inner primaries and the secondary feathers are conspicuously white. This precise arrangement results in a dark triangle or wedge shape of dark coloration forming at the wingtip when viewed against the paler inner wing and white body. This high contrast pattern is often more reliable for distant offshore identification than trying to judge the variable head color based on age or season.
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