Yellow-bellied Flycatcher - Empidonax flaviventris

Yellow-bellied Flycatcher undergoes a partial preformative molt, mostly prior to fall migration; partial to incomplete prealternate molts and incomplete to complete prebasic molts occur on the wintering grounds. This sequence of molts results in distinct molt limits among the median or greater coverts (fall-winter) or among the primaries and secondaries (spring-summer), and allows for FCF (HY), FCA (SY), and DCA (ASY) birds to be distinguished through fall migration. 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.

Yellow-bellied Flycatcher is similar in appearance to several other Empidonax flycatchers, most notably Acadian, Cordilleran, and Pacific-slope. Note the yellowish and rounded eye-ring and combination of uniform and distinctly green upperparts and yellowish throughout the underparts.

Quick tips

• Examine the primaries and secondaries for evidence of an eccentric molt, which is absent in FCF (HY) birds, but typically present to some degree in all older age classes.
• Check the shape and condition of the rectrices. They are narrow and pointed on FCF (HY) birds, vs. broad and rounded for all older age classes, but they appear fresher on FCA (SY) individuals than on DCA (ASY) individuals.
• Look for a distinct molt limit among the greater coverts in FCF (HY) and DCA (ASY) birds, or between the greater and primary coverts in FCA (SY) birds; DCB (AHY) individuals generally lack such a molt limit, but note that this plumage is generally only seen on the wintering grounds.

Species account prepared by McGill Bird Observatory (2018). Last updated by Marcel Gahbauer (Mar 2022)