Gray-cheeked Thrush has a partial preformative molt but no prealternate molts. Age can usually be determined reliably through examination of the primary and greater coverts, but some intermediates may become more difficult to identify by spring and should be considered M-FCF (AHY) unless multiple characteristics indicate a particular age. Sex can generally be determined only by brood patch / cloacal protuberance during the breeding season.
Gray-cheeked Thrush is particularly similar in appearance to Bicknell's Thrush and should be identified with care in areas where both may occur. Gray-cheeked Thrush generally shows less yellow on the lower mandible and minimal contrast between the back and tail; consider also wing and tail measurements (see Pyle 1997).
Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)
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FCJ - (HY: June - August) | |||
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Upperparts grayish-brown with pale spotting; greater coverts with distinct pale streaks along shaft tips | |||
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FCF - (HY/SY: July - following August) | |||
Retained greater coverts shorter, slightly paler, and often with a small to moderate pale streak along the shaft tips, especially in fall; rectrices relatively narrow and pointed; p10 broad, rounded, and 3-7 mm shorter than the primary coverts | |||
U |
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DCB - (AHY/ASY: July - following August) | |||
Greater coverts uniformly brown, similar to primary coverts; rectrices relatively broad and rounded; p10 narrow, pointed, and 5-12 mm shorter than the primary coverts | |||
U |
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FPJ - (HY: June - August) | |
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Similar to FCJ; some natal down remaining and/or juvenile flight feathers still growing in | |
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FPF - (HY: July - September) | |
Similar to FCF; body feathers, some to all median coverts, and up to five inner greater coverts being replaced | |
No images available yet | |
SPB - (SY: July - August) | |
Flight feathers being replaced, with retained juvenile primaries, secondaries, and/or primary coverts distinctly pale brown and worn | |
No images available yet | |
DPB - (AHY: July - August) | |
Flight feathers being replaced, with retained primaries, secondaries, and/or primary coverts either distinctly adult (relatively dark brown and not overly worn) or intermediate | |
No images available yet |
Molt classes | Age | Months | Key traits |
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M-FPF / UPU (FPF, SPB, DPB) | U | July - August | Undergoing preformative or prebasic molt, but cycle is not reliably distinguishable |
M-FCF / UCU (FCF, SCB, DCB) | U/AHY | January - December | In formative or basic plumage (molt completed), but cycle is not reliably distinguishable |