The black-throated green warbler is
easily identified by its yellow head and strong black chest pattern in
the mature males; the females have the yellow head and sometimes a bit
of black on the chest. The species is common through much of May,
peaking in the second week, and can be seen as early as late
April.
The images below illustrate the variation in the
degree of black in the throat.
Click to zoom
The Wikipedia page for this species is embedded below.
