The pine warbler is a rarity at
Magee Marsh. When it is seen here, it's typically during the
second half of April. The bird is primarily yellow with gray
wings, though the yellow is noticeably darker on the bird's head and
lighter on the bird's underside. The prothonotary warbler in full
breeding plumage has more intense yellow (almost red-yellow) that is of
a more uniform
color. Also, the prothonotary's wings are almost bluish, with
olive-gold wing coverts. The other predominantly yellow warblers
are
the prairie warbler, which has very
distinctive black markings on the face and flank that the pine lacks,
and the much more common yellow warbler,
which in full breeding plumage has red stripes on the breast.
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The Wikipedia page for this species
provides more information, and is embedded below: