I was not aware of such a thing.
You don't have to be an ornithologist to know that red northern cardinals are male and brownish-gray ones are female.
But what about a Cardinalis cardinalis that sports red feathers on one side of its body and brownish-gray feathers on the other? Why, that cardinal is half-male and half-female, of course--and just such a rare bird has been observed in northwestern Illinois.
An example of a phenomenon biologists call bilateral gynandromorphism, the bird was observed for more than 40 days between Dec. 2008 and March 2010--and it certainly caught the attention of the scientists who spotted it.