This is an adult, still in full breeding plumage. I was only able to get this one backlit photo of the adult.
Shifting gears slightly from patchy molting adult shorebirds, this is a juvenile Wandering Tattler. Here all the feathers are of the same generation. The juvenal (yes, that's the correct spelling) plumage is very similar to winter (basic) plumage, but shows faint pale fringes to the mantle and wing-covert feathers, barely visible in this photo.
This is another endemic to the Pacific Ocean, but unlike the Black Turnstone and Surfbird which are confined to the Americas, this species migrates from the Arctic along both coasts to South America, Asia and Australia as well as the South Pacific Islands. In California it is a fairly common migrant along rocky shores, but scarce in winter. In Asia it is usually less common than the very similar Gray-tailed Tattler (T. brevipes).
Older field guides placed the tattlers in the genus Heteroscelus, but the AOU merged them into Tringa in the 47th Supplement.
Digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope 3 | 30X WA | hand-held (no adapter)