Today we stopped at Poulsbo's Fish Park, where there were quite a few
Mallards and Green-winged Teal on the pond. One of the teal had what
looked like an adult male green-and-chestnut head on a mottled brown
female body.

I took a look in the Pyle guide, Part II, and there is no mention of
this combination of plumages in Green-winged Teal. However, Pyle does
discuss male-type plumage in senescent female ducks. Apparently, old
females may acquire male-type plumage as a result of low estrogen
levels. The colors tend to be more muted than in males, and, while
noncolorful males usually have a mixture of brown and colorful feathers,
females have a more even wash of color. I'm not sure this is what was
going on with this duck, though, because the adult male colors were
restricted to the head, and were not muted at all. Does hermaphrodism
occur in ducks? Any ideas?

Rachel Lawson
Seattle
RachelWL at msn.com