Quiz #444 (2012-2-02) Solution

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Solution by Tony Leukering

This week's quiz bird has bluish legs, which is a wonderful feature of all ABA-area vireos (and most of those of the world). Wonderful, because that character rules out so many other options when considering an ID, such as flycatchers and warblers. Our bird's lack of a distinct eye ring (and, less obviously, of wing bars) leaves us with the superciliaried-and-plain-winged vireo species options. The very dark irides rules out the various red-eyed species (Red-eyed, Yellow-green, and Black-whiskered; immatures have paler, browner irides than does our quiz bird and adults have, well, red eyes). Additionally, the lack of a distinct contrastingly darker lower border of the crown patch also eliminates Red-eyed. So, for the second week in a row, we find ourselves in the Warbling/Philadelphia morass.

This bird's obvious dark lores and apparently dark crown strongly suggest Philadelphia Vireo, but let's go through the motions and check other features to be sure of our tentative ID. As our eyes travel down from the head, they don't get too far when alarm bells start ringing: there is no yellow on the throat, which is distinctly and obviously bright white, lacking a suggstion even of cream. Whoa! Looking farther down the bird, we note the brightest of what little yellowish is on the underparts is on the side, a typical feature of Warbling Vireo and a deal-breaker for an ID of Philadelphia Vireo, on which the brightest yellow is on the center of the breast.

While the darkness of our quiz bird's lores seem excessive for Warbling Vireo, a small minority of Warblings sport fairly substantial dark lores. However, I believe that this picture exacerbates the true darkness, because we're looking nearly straight up the loral tract, which tends to make it look darker than it would from a more perpendicular view. Finally, while the crown looks dark gray (certainly darker than that of last week's quiz bird), we cannot compare that tone to that of the back, which is nearly hidden and in deep shade, anyway.

This picture, taken by Steve Mlodinow at Crow Valley Campground, Pawnee National Grassland, Weld Co., CO, in September 2011, points out one of the features of highly-skilled and experienced birders that can flummox beginning birders: the knowledge not only of field marks, but of knowing in what situations the appearance of field marks can lead one down the garden path.

Incorrect species provided as answers:
Philadelphia Vireo - 3
Tennessee Warbler - 2
Plumbeous Vireo - 1
Bell's Vireo - 1

Congratulations to the 13 of 20 respondents getting the quiz correct:
Patty McKelvey
Ben Coulter
Robert McNab
Jeff Jones
Logan Kahle
Richard Jeffers
George Cresswell
Nathaniel Bell
Margaret Smith
Tyler Bell
Bryan Guarente
Chishun Kwong
Sean Walters

Answer: Warbling Vireo

Quiz #443 (2012-2-01) Solution

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Solution by Tony Leukering

Warbling and Philadelphia vireos tend to cause birders fits for a number of reasons, two being

1) field-guide treatments tend to be minimalist and

2) many birders are unaware of the sizable amount of plumage variation in both species (partly because that variation is not typically presented that well in field guides).

However, I believe that the primary reason is that birders tend to consider a particular feature in a dichotomy: Warbling lacks dark lores, while Philadelphia sports them in spades. No in-between. No gray areas. No studying other field characters.

Our quiz vireo presents one of many individuals of the two species in that gray area. It sports dark lores, but they are not very dark and do not contrast at all strongly, thus being at the Warbling end of the gray area. We should look at other features to confirm or reject our initial hypothesis that the quiz bird is a Warbling Vireo.

The bird's crown is pale gray, not contrasting all that strongly with the whitish superciliary nor with the greenish-gray back. In fact, the color tone of both crown and back are virtually identical. Additionally, the bird shows no suggestion of yellow on the throat, which even the dullest of Philadelphias sport. One of the other features that I use in identifying members of this duo is the darkness of the flight feathers: very dark in Philadelphia, more gray in Warbling. Because of the angle of the bird in the picture, I don't know that I'd trust the apparent coloration, but the birds remiges do appear gray rather than blackish, though the bird's tail seems very dark. However, note that most of the tail is in shadow; the base is noticeably paler.

This western Warbling Vireo (western members of the species tend to be brighter than eastern members) was photographed at Prewitt Reservoir, Logan Co., CO, by Steve Mlodinow in September 2011.

One submitted answer omitted capital letters, so was considered incorrect for the competition.

Incorrect species provided as answers:
Philadelphia Vireo - 1

Congratulations to the 27 of 28 getting the quiz correct:
Tyler Bell
Ben Coulter
Robert McNab
Christian Nunes
Kirk Huffstater
Margaret Smith
Nick Komar
Jeff Jones
Michael & Nathaniel Behl
Logan Kahle
Su Snyder
George Cresswell
Thomas Hall
Richard Jeffers
Bill Blackburn
David Elwonger
Margie Joy
Pam Myers
Chuck Carlson
Jim Kopitzke
Sean Walters
Burke Angstman
Marcel Such
Bryan Guarente
Joe Bens
Stuart Hopper
Chishun Kwong

Answer: Warbling Vireo