Disregard my previous report of a very dark juv. California Gull. I wasn't satisfied with that ID after reviewing my photos, suspecting that is was actually a juv. Heermann's, and the experts agree that's what it is. To look for this bird, take West Jester Park Drive in Polk City all the way to its end, which will be the parking lot at the Big Creek spillway. The bird was walking around on the point there.