I think I like this for White-rumped Sandpiper. Here is the thought process: it does appear to be as big or close to the size of the Dunlin. It has dense streaking over the entire chest forming a bib, which narrows it down a lot. The first sandpiper that has that chest pattern that comes to mind is Pectoral, but it can’t be Pectoral because of the white supercilium, the bill seems too short, the head and breast don’t seem dark enough, there is no sign of yellow legs, it just overall doesn’t feel right for Pectoral. Could the apparent size be deceiving in the photo? It must be a calidris sp. because of that short bill and obvious supercilium. Definitely not Baird’s because of the chest pattern and color, and not long enough wings. I looked at pictures of White-rumped x Dunlin hybrids and they have too long of a bill. I think the process of elimination strongly points towards White-rumped, which would explain the chest streaking, and the bold white supercilium, although this is not my normal search image of them. None of the small calidris sandpipers are candidates in my mind due to the chest pattern. Least does have a streaky chest like that but the bill doesn’t match, nor does the color, with Least being a dark brown color. This bird is really on the paler side of the spectrum. The wings don’t really seem long enough for White-rumped but maybe it’s the angle? That doesn’t worry me as much for White-rumped whereas I don’t think Baird’s would ever appear this short winged… Not sure what else it could be.