While checking the town pier area for shorebirds mostly muddy with the tide out, I found this individual swimming in the shallow water very close to shore and near the yacht club pier. The rusty plumage, lighter throat and unremarkable bill coloring (vs white with black ring of breeding plumage)are all normal aspects of "basic" a/k/a winter plumage. These guys aren't typically found on the salt water of the bay except during migration; in Duxbury they seem to prefer the freshwater locales found more inland (ponds, lakes).