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Number of species: 71

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Mourning Warbler - Geothlypis philadelphia

Mourning Warbler has a partial preformative molt, and limited prealternate molts that are primarily restricted to body feathers, but may include up to three inner greater coverts in first cycle (SY) birds. Sex can generally be distinguished by plumage from the first prealternate molt onward, but in many younger birds the plumage characteristics are too intermediate to determine sex reliably.

Especially in areas of range overlap or where either species is unexpected, carefully examine plumage features and measurements to differentiate from MacGillivray's Warbler.

Quick tips

  • Look at the throat and upper breast - it is gray with extensive black mottling on DCB/DCU (AHY/ASY) males or partial black mottling on FCU (SY) males, gray with a contrastingly paler to whitish throat on FCU and DCB/DCU (AHY/ASY) females, and gray with a yellowish wash on FCF (HY) birds of both sexes.
  • Check for an eye ring - on HY (FCF) birds of both sexes it is buffy-white, on FCU (SY) females and some DCB/DCU (AHY/ASY) females it is grayish-white, while other older females as well as all DCB/DCU (AHY/ASY) males and FCU (SY) males lack an eye ring.
  • Consider the tail - on FCF/FCU (HY/SY) birds the rectrices are typically relatively narrow and pointed, while on AHY/ASY birds they tend to be somewhat broader and more rounded.
  • Check the wing for a slight contrast between the somewhat brownish primary coverts and more greenish greater coverts on FCF/FCU (HY/SY) individuals, whereas DCB/DCU (AHY/ASY) birds have more uniformly olive-green wings, but note that even when present, the molt limit can be subtle, especially in fall.

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: June - August)
Brownish wash above; buffy below
No images available yet
FCF - (HY: July - December; SY January - April)
Rectrices quite narrow and pointed; primary coverts slightly browner than the greenish greater coverts; throat grayish with a buffy wash; faint eye ring buffy-white; head brownish (F) to grayish (M)
M
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F
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FCA - (SY: February - August)
Rectrices quite narrow and pointed; primary coverts browner than the greenish greater coverts; throat grayish white (F) or gray with black mottling at the base (M); eye ring whitish (F) or absent (M)
No images available yet
DCB - (AHY: June - December; ASY January - April)
Rectrices somewhat broad and rounded; primary coverts with greenish edging, similar to greater coverts; throat grayish white (F) or gray with black mottling at the base (M); eye ring whitish (F) or absent (M)
M
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F
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DCA - (ASY: February - August)
Rectrices somewhat broad and rounded; primary coverts with greenish edging, similar to greater coverts; throat grayish white (F) or gray with black mottling at the base (M); eye ring whitish (F) or absent (M)
No images available yet

Individuals in active molt

FPJ - (HY: June - August)
Similar to FCJ; some natal down remaining and/or juvenile flight feathers still growing in
No images available yet
FPF - (HY: June - August)
Similar to FCF; median and greater coverts being replaced
No images available yet
FPA - (SY: January - May)
Similar to FCF; some head and body feathers being replaced, as well as up to three inner greater coverts
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 (relatively dark, less worn) or intermediate
No images available yet
DPA - (ASY: January - May)
Similar to DCB; some head and body 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 - August Undergoing preformative or prebasic molt, but cycle is not reliably distinguishable
M-FCF / UCU (FCF, SCB, DCB) U/AHY July - 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