Blue Jay has a partial preformative molt and no prealternate molts. Determination of sex is limited to brood patch / cloacal protuberance during the breeding season.
Species account prepared by McGill Bird Observatory (2018). Last updated by Marcel Gahbauer (Mar 2022)
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FCJ - (HY: May - August) | |||
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Similar to FCF, but with more grayish on the face, back, and wings | |||
No images available yet | |||
FCF - (HY/SY: June - following August) | |||
Primary coverts and alula grayish and lacking bars; upper mandible lining whitish to mottled black and white; outer greater coverts duller than replaced inner greater coverts on some individuals; central rectrices sometimes contrastingly bright blue | |||
U |
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DCB - (AHY/ASY: June - following August) | |||
Primary coverts and alula blue with dark barring; upper mandible lining mostly to entirely black; greater coverts uniformly bright blue with distinct white tips; central rectrices not contrasting substantially with others | |||
U |
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FPJ - (HY: May - July) | |
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Similar to FCF, but with more grayish on the face, back, and wings; some natal down remaining and/or juvenile flight feathers still growing in | |
No images available yet | |
FPF - (HY: June - October) | |
Similar to FCF, with some to all greater coverts and tertials being replaced, and sometimes also the central rectrices | |
No images available yet | |
SPB - (SY: June - September) | |
Flight feathers being replaced, with retained juvenile primaries, secondaries, and/or primary coverts distinctly dull 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 (bluish, with moderate wear) or intermediate | |
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 | January - December | In formative or basic plumage (molt completed), but cycle is not reliably distinguishable |