Rare Half-Male, Half-Female Cardinal Spotted In Pennsylvania

Bird is what's known as a bilateral gynandromorph, with male and female traits. This happens when female egg with two nuclei is 'double fertilized' by two sperm. The amazing male-female chimera was spotted in a Pennsylvania backyard. Male cardinals have bright red coloring; females have a much duller appearance.

Gynandromorphy like that in this cardinal occurs when a female egg cell develops with two nuclei—one with a Z and one with a W—and it's "double fertilized" by two Z-carrying sperm. The chimeric individual then develops with half of its body as a male ZZ and the other half as a female ZW. If you were to examine a cell from the bright red male side, it would have cells with ZZ chromosomes. If you looked at a cell from the left, it would have cells with ZW chromosomes. This phenomenon happens in birds, many insects, and crustaceans. (Be sure to check out this butterfly that's half male, half female with colors split down the middle and this half-orange, half-brown lobster.)