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Number of species: 71

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Wood Thrush - Hylocichla mustelina

Wood 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.

Quick tips

  • Look at the greater coverts - on FCF (HY/SY) birds, up to a few innermost ones are generally longer and uniform in colour, while the remainder (sometimes all) are retained juvenile feathers and often show buffy-white shaft streaks, although these may be less evident by spring; the absence of such streaks should therefore not be used as evidence of DCB (AHY/ASY).
  • Examine the outermost primary (p10) - on FCF (HY/SY) birds it is broad and 0 to 4 mm shorter than the primary coverts, while on DCB (AHY/ASY) birds it is narrow, pointed, and 3 to 6 mm shorter than the primary coverts.
  • Consider the shape of the rectrices - they are narrow and relatively pointed on FCF (HY/SY) birds, but broad and relatively rounded on DCB (AHY/ASY) birds.

Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)

The molt categories displayed below may be filtered by month.

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Click on any image below to bring up the side-by-side comparison tool.

Individuals not in molt

FCJ - (HY: May - August)
Upperparts dull brown with pale spotting; greater coverts with distinct pale streaks along shaft tips
No images available yet
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 0-4 mm shorter than the primary coverts
U
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Thumbnail - MG2-2421-70887-Hylocichla_mustelina_AOU_7_52-3038.jpg Thumbnail - MG2-2421-70887-Hylocichla_mustelina_AOU_7_52-3138.jpg Thumbnail - MG2-2421-70887-Hylocichla_mustelina_AOU_7_52-3137.jpg
DCB - (AHY/ASY: July - following August)
Greater coverts uniformly brown, similar to primary coverts; rectrices relatively broad and rounded; p10 narrow, pointed, and 3-6 mm shorter than the primary coverts
No images available yet

Individuals in active molt

FPJ - (HY: May - August)
Similar to FCJ; some natal down remaining and/or juvenile flight feathers still growing in
No images available yet
FPF - (HY: July - August)
Similar to FCF; body feathers, some to all median coverts, and up to four 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

Applicable unknown plumage/age classes

Molt classes Age Months Key traits
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