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Number of species: 82

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Alder Flycatcher - Empidonax alnorum

The molt strategy of Alder Flycatcher remains somewhat unclear. What is known is that all molt occurs on the winter grounds; the preformative molt appears to be incomplete to possibly complete in some individuals, while a distinct prealternate molt is likely absent. Sexes are identical in plumage; breeding females have a brood patch, but males have a poorly developed cloacal protuberance and may be more difficult to identify with confidence.

Alder and Willow Flycatcher are nearly identical in appearance and are usually identified reliably only through vocalizations; collectively they are referred to as Traill's Flycatcher. The description in this account likely applies also to eastern Willow Flycatcher, but not to western Willow Flycatcher.

Quick tips

  • Look at the wing bars, which are buffy on FCJ (HY) individuals but whitish on older M-FCF (AHY) birds.
  • Examine the rectrices, which are narrow and pointed on FCJ (HY) birds, but broader and more rounded on M-FCF (AHY) individuals.
  • Check for an eccentric molt limit among the primaries and secondaries, with retained faded juvenile feathers among the inner primaries and/or outer secondaries indicating FCA (SY) from spring through fall.

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 - December; SY January - February)
Buffy wing bars; rectrices somewhat narrow and pointed; note that this plumage is typically retained until after fall migration
U
Thumbnail - MG2-9900-15001-Empidonax_alnorum_AOU_7_52-3544.jpg Thumbnail - MG2-9900-15001-Empidonax_alnorum_AOU_7_52-3542.jpg Thumbnail - MG2-9900-15001-Empidonax_alnorum_AOU_7_52-3543.jpg
M-FCF - (ASY: January - December)
Plumage largely uniform in wear, with no contrastingly pale feathers retained
U
Thumbnail - MG2-2500-65556-Empidonax_alnorum_AOU_7_52-3547.jpg Thumbnail - MG2-2500-65556-Empidonax_alnorum_AOU_7_52-3545.jpg Thumbnail - MG2-2500-65556-Empidonax_alnorum_AOU_7_52-3546.jpg

Individuals in active molt

FPJ - (HY: June - July)
Similar to FCJ; some natal down remaining and/or juvenile flight feathers still growing in
No images available yet
FPF - (SY: January - March)
Similar to FCF, with all feather tracts potentially undergoing replacement
No images available yet
M-SPB
Description to be developed.
No images available yet

Applicable unknown plumage/age classes

Molt classes Age Months Key traits
M-FPF / UPU (FPF, SPB, DPB) U January - March 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
M-SPB / UPU (SPB, DPB) AHY January - February Undergoing prebasic molt, but cycle is not reliably distinguishable

Number of species: 82

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