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Some birds are notoriously tricky to identify – many Empidonax flycatchers, some large gulls, some shorebirds. If there is one group that poses an underappreciated identification challenge it's the Catharus thrushes. In the U.S. and Canada we only have five species that regularly occur – Swainson's Thrush, Hermit Thrush, Veery, Gray-cheeked Thrush and Bicknell's Thrush. But these five species can present some very real identification challenges.
The shape and spotted underparts of this bird can leave us with little doubt that we are dealing with one of the dreaded Catharus. One of the most important characteristics to look for on any Catharus thrush is the face pattern, and this bird shows why. Our bird has a distinctive spectacle on the face created by the strong pale eye ring and superloral – a face pattern that is really only shown by Swainson's Thrush. These contrast strongly against the darker face. No Veery, Gray-cheeked or Bicknell's Thrush would show this strong of a facial pattern with contrasting eye ring and a buffy supraloral area. Some Hermit Thrushes may come close to this individual, but Hermit Thrushes show a dark area that separates the pale eye-ring from the pale supralores. So if you answered Swainson's Thrush – well done, you're still in the running for the binocular!
But there is more to identifying Swainson's Thrushes than simply getting it to Swainson's Thrush. Which Swainson's Thrush? The plumage differences between these Olive-backed and Russet-backed Swainson's Thrushes are at least as great as those between Bicknell's and Gray-cheeked Thrushes.
The warm brown upperparts on this bird may call to mind Russet-backed Swainson's Thrush. But the eye-ring is on the heavy side for Russet-backed Swainson's Thrush – more what we would expect with Olive-backed Swainson's Thrush. More importantly, the flanks on this bird appear olive without the rufous expected on Russet-backed Swainson's Thrush. Look particularly at the flanks near the primary coverts where there is no hint of rufous at all. From what we can see, the breast spotting appears quite extensive, another feature of Olive-backed Swainson's Thrush.
For more on Catharus Thrush ID, see Dan Lane and Alvaro Jaramillo's excellent three part series in Volume 32 (issues 2-4) of Birding. Use some caution when looking at these photographs, many of them were taken using a flash. While flash photography makes for some pretty pictures, it can also make birds appear considerably different than they would in the field.
With the addition of this image of the same bird we can be more confident that this is an Olive-backed Swainson's Thrush given the olive flanks and distinct spotting on the breast. That these images were taken in Colorado is another strong clue that this is an Olive-backed Swainson's Thrush. Of course judging colors on photographs is challenging, even more so when they are viewed on a variety of computer monitors. For that reason, perhaps it's safest to leave this bird as a Swainson's Thrush.
This Swainson's Thrush was photographed by Bill Maynard at Chico Basin Ranch, El Paso County, Colorado in May of 2006.
The following people (listed by submission date beginning with the earliest) submitted correct answers for the June Bird Photo Quiz—Swainson's Thrush:
The following list shows the number of submissions for each species guessed.
The photo and answer for this quiz were supplied by Chris Wood.