tags: Chestnut-sided Warbler, Dendroica pensylvanica, birds, mystery bird, bird ID quiz
[Mystery bird] Adult male Chestnut-sided Warbler, Dendroica pensylvanica, in breeding plumage, photographed on the grounds of the USGS EROS Data Center in Minnehaha County, South Dakota. [I will identify this bird for you tomorrow]
Image: Terry Sohl, 22 May 2008 [larger view].
Photo taken with Canon 40D, 400 5.6L.
Please name at least one field mark that supports your identification.

That's an adult male Chestnut-sided Warbler in breeding plumage. Sibley mentions "chestnut sides", "yellow crown", "white cheeks", and "white underparts", all of which are well-shown here.
It's also a good example of the kind of ridiculously gorgeous bird that makes me really love bird watching. How could anyone not love looking at a bird like that?
Regulus satrapa: "Golden-Crowned Kinglet" (Golden Crown, obvious status as a "peep")
Bappy belated B-day from another PZ Minion!
I have to agree with the warbler - the kinglet pictures I see don't have the chestnut on the sides and the beak is shaped differently.
Chestnut-sided Warbler. Chestnut-colored sides, double wing-bars, white belly, yellow crown .....
It was your comment "brought tears to my eyes that made me wonder what your "mystery bird" was today.
Perhaps you can explain the reason for the tears?
"Chessies" nest near my house in Campton, NH.
Best wishes, Susan
No doubt about the ID on this one. Chestnut-sided Warbler with the chestnut coloured sides and yellow cap..umistakeable.
Sorry I missed your "Happy Birthday!" Regards, M.