In a backyard in Erie, Pa., an unusual cardinal may be a gynandromorph

Researchers believe that the cardinal frequenting the Caldwells’ bird feeder in Erie, Pa., is a rare bilateral gynandromorph, half male and half female. Not much is known about the unusual phenomenon, but this sexual split has been reported among birds, reptiles, butterflies and crustaceans. No one can be sure the bird is a gynandromorph without analyzing its genes with a blood test or necroscopy, but the split in plumage down the middle is characteristic of the rare event, according to Daniel Hooper, an evolutionary biologist at the Cornell University Lab of Ornithology.

Source: www.nytimes.com