The BBC is reporting on new research on gynandromorphous chickens, whose bodies are half male and half female, divided along the plane of bilateral symmetry. The article is unclear on the exact process that causes the condition. It is apparently the result of entanglement between two separate embryos, the process which, at a later stage of embryonic development, leads to two-headed snakes, and conjoined human twins.
I am wondering—is this kind of gynandromorphy unique to chickens, or does it occur in other birds? It would be barely noticeable in many species, but obvious in sexually dimorphic birds like woodpeckers and certain songbirds. When a half-male, half-female Northern Cardinal (Cardinalis cardinalis) shows up at the bird feeder, that would attract some attention.
I suppose that if I really wanted to know, I could do some research to find the answer, but I am too lazy.