Yellow-billed Loon, Gavia adamsii
This Yellow-billed Loon in molt from breeding plumage showed up in one of the salt ponds along the southern end of San Francisco Bay in October 2011, where it was seen and photographed by many Bay Area birders. It was a great rarity for the spot, but its location and behavior raised fears that it might be sick or injured. Sadly, these fears were realized when the bird died about a week after this photo was taken. Yellow-billed Loons closely resemble the familiar Common Loon but live further north, breeding on tundra ponds along the shore of the Arctic Ocean, and normally wintering on coastal bays in Alaska and Norway; the light-colored bill is the best mark distinguishing the two species.