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)