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I'm really puzzled about this bird. I got a brief glimpse as it flew overhead at a low height - about 30 feet. It was white, had fast wingbeats like a dove or pigeon, about the size of a dove. No sound match in the Merlin U.S. Continental bird pack.

So, I was at this location in part because of a report of a Calliope Hummingbird being sighted there. I was there with a number of others, all looking for the hummingbird. After a couple of hours of seeing nothing (except all the other, non-hummingbirds that I got excited about...) This very small hummingbird flew in. It was clearly not the male Calliope that had been reported, but there was some speculation it might be a female Calliope. I can't see it, though, and suspect either Allen's or Rufous. I'm posting it here, though, in hopes that I'm wrong. Calliope would be a new one for me.

Some sort of extremely darkly-colored duck. Has exactly the body shape and size of a wild mallard. Flies and makes vocalizations like a wild drake mallard. Currently residing in and around an office park pond in Palo Alto, CA.

The first picture isn't great, but I've since posted four much better pictures afterward. Besides the nearly solid-black body, note especially the bright blue speculum, which is the only substantial color on this individual.