Common Yellowthroat - Geothlypis trichas

Common Yellowthroat has a partial to incomplete preformative molt that replaces all median and greater coverts and can include the greater alula, up to all three tertials, some to all rectrices, and occasionally up to five inner secondaries and five outer primaries. The prealternate molts are absent to partial, mostly restricted to body feathers and up to three inner greater coverts. Molt limits can be subtle and by spring the differences in feather wear by age can be slight, so some intermediates are not reliably aged and should be considered M-FCU (AHY). All birds with black on the face are males, but some FCF (HY) males may lack black, and therefore those without black should generally be considered sex unknown rather than female.

Conseils clés

• Look at the face - only males have a black mask, but note some FCF (HY) males may also be entirely lacking black.
• Examine the tail: uniformly narrow and pointed rectrices OR contrastingly fresh and broad replaced central rectrices indicate FCF/FCU (HY/SY), while uniformly broad and relatively rounded recrtices are typical of DCB/DCU (AHY/ASY) individuals, but can occasionally occur on FCF/FCU (HY/SY) birds that have undergone a particularly extensive preformative molt, including replacement of outer primaries.
• Look at the primary coverts - on FCF/FCU (HY/SY) birds they are somewhat browner and more worn than the greater coverts, while on DCB/DCU (AHY/ASY) birds they are similar in colour and wear with the greater coverts; however, the contrast on FCF/FCU (HY/SY) birds can be quite subtle, and should not be used as the sole ageing criterion unless it is particularly distinct.

Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)