This beautiful juvenile Pectoral Sandpiper (Calidris melanotos) was feeding among the algae and shallow rocky pools, possibly on amphipods.
A slightly closer picture (below) allows a view of the yellow legs and the slightly decurved bill (with pale base).
In the next picture, look for the rufous feather edges and the strong contrast between the finely streaked and buff-colored breast and the white belly.
Pectoral Sandpipers often have an upright stance with a long neck (next image). And once again, note the contrast between the dark upper breast and pale underparts.
Last September I posted a recording of Pectoral Sandpiper calls from Bodega Harbor. To hear them, click here.
P.S. Pectoral Sandpipers are uncommon migrants in this area. They're passing through on their way between arctic breeding sites and wintering grounds in South America.
P.P.S. In my experience, it's somewhat unusual to see Pectoral Sandpipers on rocks. They tend to prefer grassy areas, or tidal flats. So it was interesting to see this individual exploring rocky habitat.