Took a walk around lake Ralphine and Spring Lake today, in Santa Rosa. Saw 40 bird species: Downy woodpecker, Nuttal's woodpecker, acorn woodpecker, turkey vulture, crows, lesser goldfinch, house finch, ruby-crowned kinglet, northern flicker, robin, Western meadowlark, ring-billed gull, coots (22), common moorhen (2), scrub jay, oak titmouse, chestnut-backed chickadee, yellow-rumped warbler, great egret, snowy egret, spotted towhee, California towhee, fox sparrow, golden-crowned sparrow, white-crowned sparrow, song sparrow, marsh wren, Bewick's wren, belted kingfisher, Great blue heron, Canada geese, mallards, buffleheads (10), greater scaup (6), common merganser (27 on Lake Ralphine), pied-billed grebe, a spotted sandpiper, a red-shouldered hawk, an Osprey eating a fish up in a tree, and a pair of common goldeneyes.
The photos are of a male (top) and female common merganser. These birds show striking sexual dimorphism--strictly speaking, sexual dichromatism.