Monday, November 5, 2012
Quiz #473 (2012-4-05) Solution
Solution by William von Herff and Tony Leukering
William von Herff provided a good solution, so I'll start with that.
"Well, here we have a bird clinging parallel to the trunk of a tree. We can see the tail, therefore we can assume that the bird is facing up. The only two families of ABA-area birds that cling vertically to trees are the creepers and woodpeckers. Brown creeper can be eliminated because it has a mottled brownish back, while this bird has a distinctly unpatterned black back, so it is a woodpecker. Now, it's time to start dissecting the field marks!
"First of all, the underside of this bird is mostly off-white. That eliminates most ABA-area woodpeckers; in fact, all except Red-headed, Golden-fronted, Red-bellied, Gila, Hairy, and Downy. Now, there is the black back with a big patch of white. The "solid black" part eliminates all of the options except Red-headed. But does that match up with the white patch? Well, Red-headed has a big white patch on the secondaries, so that matches."
Thanks, William. I will just add a few confirmatory points and discuss the bird's age. This quiz photo is an excellent illustration of the importance of using as many features in a bird's ID as one can manage. While sapsuckers also sport large white wing patches, they do not have mostly whitish underparts. As noted by William, the large white wing patch is composed of secondaries; the white wing patches on other woodpeckers are of different placement: those of sapsuckers are composed of secondary coverts, while those of the 'Centurus' ladder-backed species and Acorn and White-headed woodpeckers are composed of primary coverts and/or bases of primaries. Also, looking closely at the near edge of this white patch, we can discern two short, parallel black bars (indicated by arrows on inset, below), which is all we need to determine the bird's age as a first-cycle bird. Those faint bars on the bird's side adjacent to the white wing patch provides a feature confirming the bird's age.
I have also provided, below, the picture that I took of this individual before the one used as the quiz photo at Cox Hall Creek Wildlife Management Area, Cape May Co., NJ, on 8 January 2012. Note that those black bars in the wing patch are longer with the wing open. Also note, and this is very important when dealing with wing features, how the placement and shape of the white patch change from open wing to closed.
Incorrect species provided as answers:
Yellow-bellied Sapsucker - 3
Williamson's Sapsucker - 1
Congratulations to the 16 of 20 getting the quiz correct:
William von Herff
Answer: Red-headed Woodpecker