Spotted or Common Sandpiper? (1 Viewer)

[Muratfaik]

Both adults and juveniles have a complete, or mostly complete, post-breeding/post-juvenile moult, respectively, though typically this occurs from October, on the wintering grounds. Adults can, however, sometimes begin this moult, including the tail and tertials and, occasionally, up to six inner primaries, before migrating, which is presumably what is going on here.

Thanks for the article. Do you think this picture where you can see the upperwing clearly, complies with the moulting strategy you suggest? I see on the left wing, there are two missing flight feathers.

 

[Butty]

Do you think this picture . . . complies with the moulting strategy you suggest?

4 inner primaries already new + 2 growing (and all secondaries already renewed?) - so... yes.