Dr. Peer watched the bird over two winters, but it eventually was pushed out of the teacher’s yard by a male cardinal that aggressively defended its territory. The gynandromorph wasn’t seen again.

A recently spotted cardinal in Erie, Pennsylvania, that is part male, part female, is a gynandromorph, referring to a mutation that occurs in insects, birds, and even chicken.

Exclusive video reveals half-male, half-female cardinal Birdwatchers in Erie, Pennsylvania, found an incredibly uncommon bird—in their backyard.

This bi-colored northern cardinal has female plumage on its right, and male plumage on its left. Called a “gynandromorph,” these animals are rare in nature.

Hill, 69, who has been watching birds for 48 years, said he'd never seen one comparable with the bilateral gynandromorph northern cardinal. "This has been the most exciting," he said.

For the cardinal, the bright red side and the head is male, and the brown side is female. “What’s going on is that the bird has both male and female gonads, and they are both actively ...