The mallard is perhaps the most familiar and recognizable of the 20 or more duck species found in Florida. The male mallard, that is. Sporting a bright yellow bill and a vivid "ski mask" of iridescent green feathers, he's a common sight on lakes and ponds throughout the bay area.

The mallard hen is equally exquisite, but in a much less obtrusive way. She's smaller than her mate; and her variegated plumage is mostly brown, ensuring that she's well camouflaged during the spring nesting season, when she's most vulnerable to predators.

It's a trait biologists call "sexual dimorphism," in which the two genders of a single species have radically different appearances. In the case of the mallard, the male dons the regal finery, while the female goes (ahem) "hencognito."