A bird hopping outside the window lately is the strangest that Shirley and Jeffrey Caldwell have ever seen. Its left side is the taupe shade of female cardinals; its right, the signature scarlet of males. 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. He said that gynandromorphs could theoretically be created through the fusion of two developing embryos that were separately fertilized.

Source: New York Times February 09, 2019 18:13 UTC