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Number of species: 79

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Least Flycatcher - Empidonax minimus

Least Flycatcher undergoes a partial preformative molt and partial to incomplete prealternate molt. The preformative molt occurs mostly prior to fall migration; older birds may begin their prebasic molt on the breeding grounds but replace most of their feathers after migration. Because of this, FCF (HY), FCA (SY), and DCA (ASY) individuals may be distinguishable through fall migration, although FCA and DCA plumages can be difficult to reliably distinguish, warranting use of M-FCA (AHY) in many cases. Sexes are identical in plumage; breeding females have a brood patch, but males have a poorly developed cloacal protuberance and may be difficult to identify with confidence.

Least Flycatcher is similar to other small Empidonax flycatchers (especially Dusky and Hammond's) and should be identified with caution especially where ranges overlap.

Quick tips

  • Look at the wing bars, which are buffy on FCF (HY) individuals, mixed white/buffy on FCA (SY) individuals, a more subtle contrast between whitish and yellowish on DCA (ASY) individuals, and uniformly whitish on DCB (AHY) individuals.
  • Examine the rectrices, which are narrow and pointed on FCF (HY) and some FCA (SY) birds, mixed pointed and rounded on some FCA (SY) birds, and uniformly rounded on DCA (ASY) and some FCA (SY) birds.

Species account prepared by McGill Bird Observatory (2018). 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 - September)
Brownish upperparts; buffy wing bars
No images available yet
FCF - (HY: July - December; SY January - April)
Greater coverts with buffy tips; rectrices generally narrow and pointed
U
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FCA - (SY: February - October)
Inner whitish-tipped greater coverts contrasting with duller and buffy-tipped outer coverts; some to all rectrices often narrow and pointed, but all broad, rounded, and fresh on some individuals
U
Thumbnail - MG2-2600-16214-Empidonax_minimus_AOU_7_52-3559.jpg Thumbnail - MG2-2600-16214-Empidonax_minimus_AOU_7_52-3557.jpg Thumbnail - MG2-2600-16214-Empidonax_minimus_AOU_7_52-3558.jpg

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DCB - (AHY: July - December; ASY January - March)
Greater coverts with whitish tips; rectrices generally broad and rounded
No images available yet
DCA - (ASY: March - October)
Inner whitish-tipped greater coverts contrasting slightly with duller and yellowish-tipped outer coverts; rectrices generally broad and rounded with central feathers sometimes contrasting fresh
U
Thumbnail - MG2-2460-40489-Empidonax_minimus_AOU_7_52-3553.jpg Thumbnail - MG2-2460-40489-Empidonax_minimus_AOU_7_52-3551.jpg Thumbnail - MG2-2460-40489-Empidonax_minimus_AOU_7_52-3552.jpg

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: July - October)
Similar to FCF, with some body feathers and rarely a few wing coverts being replaced
No images available yet
FPA - (SY: January - May)
Similar to FCA, with most to all median coverts, some to most greater coverts, some to all tertials, and some to all rectrices being replaced
No images available yet
SPB - (SY: July - November)
Flight feathers being replaced, with retained juvenile primaries, secondaries, and/or primary coverts distinctly brownish and very worn
No images available yet
DPB - (AHY: July - November)
Flight feathers being replaced, with retained primaries, secondaries, and/or primary coverts either distinctly adult (grayish, with moderate wear) or intermediate
No images available yet
DPA - (ASY: February - April)
Similar to DCA, with the median coverts, some to all greater coverts, some to all tertials, and occasionally the central rectrices being replaced
No images available yet

Applicable unknown plumage/age classes

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

Number of species: 79

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