I was browsing through the local bird listeserv, as I do at least once a day, to see if there were any newly arrived migrants or unusual birds in our area. The listserv is a good way to get a feel for what birds one might encounter on a local outing as well as in the rest of the Carolinas. I hadn’t seen some of the birds that I hoped that I would see so far this season, like pine siskin, and wondered if anyone else in the immediate area had reported any of the little finches (a few have been seen, but not here at the Museum, not yet anyway).
There was one post on the listserv with the headline “Half male and half female Northern Card.” I took the bait and opened the message. The post linked to an article on the American Association for the Advancement of Science (AAAS) website about a northern cardinal which had the plumage of a female on one side of its body and a male on the other. It was a bilateral gynandromorh. Here’s the link.
The word gynandromorh means female (gyn), male (andro), and form (morph). Basically, the cardinal has the physical characteristics of both sexes. There’s a lengthy, and accurate, explanation for how this can occur in nature at the Dalton State College website.
Apparently gynandromorphism can display itself in a patchwork of differences throughout the animal’s body. Bilateral gynadromorphism more or less divides those differences equally, one sex on one side of the body, the other sex on the other side of the body.
Gynandromorphism is most often reported in insects. Butterflies seem to be the most reported gynandromorphs perhaps due to the great disparity in the size and color of the sexes, many butterflies are sexually dimorphic to a great degree. Many bird species too, differ vastly in plumage between male and female. As the cardinal above attests, gynandromorphism also occurs in birds.
Can these insects and birds reproduce? It depends. In insects the answer is most often no, but I did read an article wherein the researcher observed gynandromorphic sawflies successfully reproduce. It depends upon which of the reproductive organs the individual has developed. Sometimes they’re split right down the middle.
I suppose it also depends upon which sex the animal “thinks” it is (it would probably be more accurate to say, which hormones “tell” the bird how to act). In the case of the cardinal above, is the bird going to respond to the calls of a male singing at the top a red maple next March, build a nest and lay eggs? Or, is the bird going to be that male up in the maple singing its heart out to all within earshot that’s it’s ready to stake a claim on this territory and is ready to mate? And, is another cardinal, male or female, going to participate in the union? That’s the question, or questions. The bird may have the inclination, or be compelled, to do both or neither. I don’t think reproduction has been observed in gynandromorphic birds, but I could be wrong.
I don’t recall ever having seen a gynandromorph in the flesh, or exoskeleton, or feather (it’s something that I’d surely remember). I don’t have a photo to show you. Fortunately, there are plenty of photos, many photos, across the internet for you to browse through. If I do ever come across one of these animals, I will certainly make an effort to photograph it, whether bird or insect, and show it off to you.
I hope you will do the same.