Spencer immediately knew what was going on: the bird is a bilateral gynandromorph — a rare creature that embodies both male and female characteristics. Gynandromorphism has been previously ...

Rarer yet is the bilateral gynandromorph, an animal that’s half him and half her, split at the midline. The phenomenon has been documented in birds, crustaceans—and butterflies. Evolutionary ...

However, its sex is incredibly uncommon. The scientific term for this phenomena denotes the butterfly a bilateral gynandromorph. One of Sterling Mattoon's rarest specimens, a bilateral half female ...