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Help with a tern


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12 hours ago, Zoroark said:

With the black-tipped orange bill, orange legs, lack of black on the axillaries, and fully black cap, I believe this is a Forster's Tern.

 

7 hours ago, Charlie Spencer said:

Nice break-down!

Caution; Tern ID is fraught with challenges! The field marks listed above do little to separate Common and Forster's Terns. Adults of both species arrive before immature birds, and typically arrive already in alternate plumage, with black caps and orange or orange-red bills with black tips. Neither species has black axillaries.

I agree with Forster's Tern though, because it is relatively light/whitish below, and shows dark tips to the primaries which are not as broad and dark like Common. The dark wedge transition on the outer primaries (often referred to as a "primary wedge") can be challenging to distinguish in flight, as can the dark margins to the outer rectrices. Common Terns also molt their inner primaries on their wintering grounds so they often have a translucent panel on the inner primaries. This bird lacks that, and does appears to have a larger bill, which supports FOTE.

 

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