Update January 2011: added text at bottom referring to the newer Pyle ID Guide that does feature Bicknell's Thrush. Update: added two more pics
of bird X), at the bottom.
More photos of thrushes from the Spring 2005 migration through
coastal Texas:
X) May 08/09; Packery Channel, Corpus Christi, Neuces County:
The light was dull and I needed to use flash on first photo, leading
to it being a bit washed-out. Also the parameter settings I use
on my camera tend to weaken color saturation, so I have increased
the saturation of these images slightly. Even so, they still fall
a bit short of the warmth seen in the field. All adjustments were
made to the whole image:
In the copy below of the above image, I've marked my estimation
of the parallel visible tertial length (TL; where the measurement
is taken from the tip of the longest tertial to the tip of the
longest covert in a parallel line with the measurement for primary
projection), and the primary projection (PP). The ratio is 0.92:
- but the maximum visible tertial length (where the measurement
is taken from the tip of the longest tertial directly to
the tip of the longest covert - to achive this I rotated the image
slightly) provides a ratio of 0.86. Compare this to the
data table in Thrush ID: gray-cheeked and bicknell'sBIRDING 32:4(see summary below) - which does not state
which of the above two methods were used:
The following two pics are without flash:
These pics are from May 09, when the natural lighting was brighter
(no saturation changes were made to these images) - these pics
are closer to how the bird actually looked to the eye the day
before:-
Here is a summary of the Bicknell's ID features mentioned in the
BIRDING article referred-to above:-
1) Primary projection: the ratio of exposed/visible tertial length
to primary projection (n = 27 for all forms) is:
BITH
0.64 - 1.10; mean 0.90
GCTH minimus
0.88 - 1.22; mean 1.02
GCTH aliciae
0.84 - 1.33; mean 1.04
2) Contrastingly warmer, browner primary coverts and primary bases
(shared to some degree with minimus GCTH).
3) Contrastingly warmer, browner uppertail coverts and retrices
(shared to some degree with minimus GCTH).
4) Slightly warmer, browner back, mantle and scapulars (shared
to some degree with minimus GCTH)
5) Bill color: the pale area is always yellowish (vs fleshy or
yellowish-flesh), and extends more than half the length of the
mandible (some color overlap with minimus GCTH; 6% of aliciae
GCTH had the pale on the mandible at least half way.)
Other features mentioned elsewhere include on average more buffy
tones to the throat/breast, and more warm (less gray) tones to
the flanks leading to less contrast with the wings. Update:two more pics from
May 08: Note the emargination on P6, and note how P7 = P8, and P9 (roughly = maybe a bit >)
P6:- this does not
match the wing formula for any of the four Catharus thrushes
illustrated in ID Guide to N. A. Passerines, by Pyle, Howell,
Yunick, and DeSante (red cover) - but that reference does not illustrate nor
discuss wing formula for bicknelli: Update January 2011: The newer ID Guide to N. A. Passerines, by Pyle (black cover) does include a separate entry for Bicknell's Thrush; on page 396 there is figure 236 illustrating the wing formula of BITH - an exact match for that described just above (written before the newer ID Guide was published) and evident in the photos below:
