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Posted by David Simpson on 07:14:55 12/15/10
In Reply to: Re: Masked Duck at Gate 15 - ENP posted by Larry Manfredi
At this time of year most male Masked ducks are in their eclipse (non-breeding) plumage. Separating male and female Masked ducks in non-breeding plumage is difficult at best. There are no diagnostic plumage differences (at least to my knowledge) between males and females when not in breeding plumage. Differentiating the sexes comes down to degrees of shading, size of white wing patch, and possibly size and structure. Without comparison to known birds or lots of experience, it is probably best not to attempt to sex the birds in winter.
We had this discussion several years ago when two masked ducks were photographed at Viera Wetlands in the winter season. One bird was decidedly brighter than the other. The brighter bird was very cooperative, the paler bird was only seen and photographed once (or vice versa?). Several people arbitrarily assigned female to the gender of the more social bird despite the lack of any satisfactory supporting evidence. It was published in FFN as a "female-plumaged" bird even though it would be more accurate to say "non-breeding plumaged."
As I recall, no one offered up any solid factors for separating male and female Masked duck in non-breeding plumage. Perhaps someone on TAS has some experience with this ID challenge.
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