The IBBA (Inland Bird Banding Association) recently caught and banded a northern cardinal that is half-male, and half-female. Quite literally (to get all science on you), the bird shows an apparent bilateral gynandromorphism that causes it to have female coloring (on its left side) and male coloring (on its right side). Even more interesting, rare birds like this have both a testis and an ovary. Check it out in their Facebook post below!
The Inland Bird Banding Association is a nonprofit organization that's dedicated to people interested in the study of birds.