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Number of species: 71

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Wilson's Warbler - Cardellina pusilla

Wilson's Warbler has a partial preformative molt, and absent to limited prealternate molts that are restricted to head feathers. Sex can generally be determined by plumage, but age can be somewhat trickier, and especially by spring there may be some intermediates that are best considered as M-FCU (AHY).

Quick tips

  • Examine the crown - DCB/DCU (AHY/ASY) males have an extensive solid black cap, FCF/FCU (HY/SY) males and DCB/DCU (AHY/ASY) females have a somewhat smaller black cap with greenish flecks (usually glossier on males), and FCF/FCU (HY/SY) females have a mottled yellow/green crown with flecks of black.
  • Look at the rectrices - on FCF/FCU (HY/SY) birds they are relatively narrow and pointed, and on DCB/DCU (AHY/ASY) birds they are relatively broad and rounded, though the contrast is not as great as on some other warblers.
  • Check for molt limits on the wing, although they can be subtle in this species - on FCF/FCU (HY/SY) birds there tends to be somewhat of a greater contrast between dull/paler primary coverts and the slightly darker and fresher greater coverts; in DCB/DCU (AHY/ASY) birds the wing is more uniform in appearance.

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 - July)
Brownish tones above and buffy below; buffy-yellow wing bars
No images available yet
FCF - (HY: May - December; SY January - April)
Crown mostly greenish (F) or largely blackish with some greenish mottling (M); rectrices often somewhat narrow and pointed; primary coverts somewhat narrow and pointed and slightly duller/paler than greater coverts
M
Thumbnail - MG2-2550-58533-Cardellina_pusilla_AOU_7_52-2795.jpg Thumbnail - MG2-2550-58533-Cardellina_pusilla_AOU_7_52-2793.jpg Thumbnail - MG2-2550-58533-Cardellina_pusilla_AOU_7_52-2794.jpg
F
Thumbnail - MG2-2550-83760-Cardellina_pusilla_AOU_7_52-2801.jpg Thumbnail - MG2-2550-83760-Cardellina_pusilla_AOU_7_52-2799.jpg Thumbnail - MG2-2550-83760-Cardellina_pusilla_AOU_7_52-2800.jpg
FCU - (SY: February - August)
Crown mostly greenish, sometimes with a bit of blackish mottling (F) or largely blackish with some greenish mottling (M); rectrices often somewhat narrow and pointed; primary coverts somewhat narrow and pointed and slightly duller/paler than greater coverts
M
Thumbnail - MG2-2630-69070-Cardellina_pusilla_AOU_7_52-2774.jpg Thumbnail - MG2-2630-69070-Cardellina_pusilla_AOU_7_52-2772.jpg Thumbnail - MG2-2630-69070-Cardellina_pusilla_AOU_7_52-2773.jpg
F
Thumbnail - MG2-2530-52001-Cardellina_pusilla_AOU_7_52-2780.jpg Thumbnail - MG2-2530-52001-Cardellina_pusilla_AOU_7_52-2778.jpg Thumbnail - MG2-2530-52001-Cardellina_pusilla_AOU_7_52-2779.jpg
DCB - (AHY: June - December; ASY January - April)
Crown mottled green and black (F) or primarily to entirely glossy black (M); rectrices often quite broad and rounded; primary coverts somewhat broad and rounded, and similar in color to the greater coverts
M
Thumbnail - MG2-2410-96778-Cardellina_pusilla_AOU_7_52-2810.jpg Thumbnail - MG2-2410-96778-Cardellina_pusilla_AOU_7_52-2808.jpg Thumbnail - MG2-2410-96778-Cardellina_pusilla_AOU_7_52-2809.jpg
F
Thumbnail - MG2-2550-58734-Cardellina_pusilla_AOU_7_52-2807.jpg Thumbnail - MG2-2550-58734-Cardellina_pusilla_AOU_7_52-2805.jpg Thumbnail - MG2-2550-58734-Cardellina_pusilla_AOU_7_52-2806.jpg
DCU - (ASY: February - August)
Crown mottled green and black (F) or primarily to entirely glossy black (M); rectrices often quite broad and rounded; primary coverts somewhat broad and rounded, and similar in color to the greater coverts
M
Thumbnail - MG2-2550-58343-Cardellina_pusilla_AOU_7_52-2789.jpg Thumbnail - MG2-2550-58343-Cardellina_pusilla_AOU_7_52-2787.jpg Thumbnail - MG2-2550-58343-Cardellina_pusilla_AOU_7_52-2788.jpg
F
Thumbnail - MG2-2520-48699-Cardellina_pusilla_AOU_7_52-2786.jpg Thumbnail - MG2-2520-48699-Cardellina_pusilla_AOU_7_52-2784.jpg Thumbnail - MG2-2520-48699-Cardellina_pusilla_AOU_7_52-2785.jpg

Individuals in active molt

FPJ - (HY: May - July)
Similar to FCJ; some natal down remaining and/or juvenile flight feathers still growing in
No images available yet
FPF - (HY: May - July)
Similar to FCF; median and greater coverts being replaced
No images available yet
FPA - (SY: January - May)
Similar to FCU; only head feathers being replaced
No images available yet
SPB - (SY: June - August)
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 - August)
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 - (ASY: January - May)
Similar to DCU; some head feathers being replaced
No images available yet

Applicable unknown plumage/age classes

Molt classes Age Months Key traits
M-FPF / UPU (FPF, SPB, DPB) U June - July Undergoing preformative or prebasic molt, but cycle is not reliably distinguishable
M-FCF / UCU (FCF, SCB, DCB) U/AHY June - April In formative or basic plumage (molt completed), but cycle is not reliably distinguishable
M-FPA / UPA (FPA, DPA) AHY January - May Undergoing prealternate molt, but cycle is not reliably distinguishable
M-FCA / UCA (FCA, DCA) AHY February - August In alternate plumage (molt completed), but cycle is not reliably distinguishable