Yellow Warbler has a partial preformative molt, and partial to incomplete prealternate molts that include some to all greater coverts and tertials. Once beyond formative plumage, sex can usually be determined by plumage, but appearance can vary considerably among individuals, and it is best to consider multiple features in determining both sex and age.
Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)
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FCJ - (HY: May - August) | |||||||||
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Largely grayish aside from some yellow on the wing and tail | |||||||||
No images available yet | |||||||||
FCF - (HY: June - December; SY January - March) | |||||||||
Primary coverts, primaries, and secondaries fairly narrow and dull, with little or no yellowish edging; rectrices usually somewhat narrow and pointed; breast generally lacking streaks (F) or with a few faint reddish streaks (M) | |||||||||
F |
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FCA - (SY: January - August) | |||||||||
Primary coverts, primaries, and secondaries brownish, contrasting markedly with yellow-edged greater coverts; rectrices usually somewhat narrow and pointed; breast with faint (F) or moderately heavy reddish streaking (M) | |||||||||
M |
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DCB - (AHY: June - December; ASY January - March) | |||||||||
Primary coverts, primaries, and secondaries fairly dark, with distinct yellow edging; rectrices usually somewhat broad and rounded; breast with few to no (F) or fairly distinct reddish streaks (M) | |||||||||
F |
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DCA - (ASY: January - August) | |||||||||
Primary coverts, primaries, and secondaries fairly dark, with distinct yellow edging; rectrices usually somewhat broad and rounded; breast with moderate (F) to heavy reddish streaking (M) | |||||||||
M |
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F |
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FPJ - (HY: May - July) | ||
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Similar to FCJ; some natal down remaining and/or juvenile flight feathers still growing in | ||
U |
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FPF - (HY: May - September) | ||
Similar to FCF; median coverts, some to all greater coverts, greater alula, and up to all tertials being replaced | ||
No images available yet | ||
FPA - (HY: December - December; SY January - April) | ||
Similar to FCA; some to all greater coverts and usually some to all tertials being replaced | ||
No images available yet | ||
SPB - (SY: June - September) | ||
Flight feathers being replaced, with retained juvenile primaries, secondaries, and/or primary coverts distinctly pale brownish and very worn | ||
No images available yet | ||
DPB - (AHY: June - September) | ||
Flight feathers being replaced, with retained primaries, secondaries, and/or primary coverts either distinctly adult (generally grayish, less worn) or intermediate | ||
No images available yet | ||
DPA - (AHY: December - December; ASY January - April) | ||
Similar to DCA; most to all greater coverts and most to all tertials being replaced | ||
No images available yet |
Molt classes | Age | Months | Key traits |
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M-FPF / UPU (FPF, SPB, DPB) | U | June - September | Undergoing preformative or prebasic molt, but cycle is not reliably distinguishable |
M-FCF / UCU (FCF, SCB, DCB) | U/AHY | June - March | In formative or basic plumage (molt completed), but cycle is not reliably distinguishable |
M-FPA / UPA (FPA, DPA) | AHY | December - April | Undergoing prealternate molt, but cycle is not reliably distinguishable |
M-FCA / UCA (FCA, DCA) | AHY | January - August | In alternate plumage (molt completed), but cycle is not reliably distinguishable |