“Halfsider” Northern cardinal, Cardinalis cardinalis. (Female plumage on the bird’s right side, male plumage on the left.) Photographed sometime between December 2008 and March 2010 in Rock Island, Illinois.
Photograph: Brian Peer & Robert Motz.
Imagine looking out your window one morning and seeing a bird at your feeding table that looks as if a male and female of the species had been cut in half lengthwise and two opposite-sex sides had been carefully sewn together to create one individual.
Perhaps you’d suspect a prank; maybe a local artist had skilfully painted the plumage on one half of a female bird to look like a male of the species? Or perhaps you’d start worrying about what sorts of illegal mind-bending substances might have been added to your food or drink?
After you became convinced that such a bird was not a product of your imagination, you might start to wonder what its life is like. Are these half male-half female birds confused?
What might it feel like to go through life as a “halfsider”?
Such “halfsider” birds are occasionally seen, but long-term observations of the behaviours and social life of a bilateral gynandromorph – as they are more properly known – are rarer than are the birds themselves.
In a newly published paper, two birders, Brian Peer, a Professor of Ecology and Curator of Birds and Mammals at Western Illinois University, and Robert Motz, share their long-term observations of a free-living “halfsider” Northern cardinal, Cardinalis cardinalis, made during more than 40 nonconsecutive days between December 2008 and March 2010.
The team report that the cardinal never appeared to pair up, nor did they ever hear it sing.
Nor did the bird respond aggressively to recorded Northern cardinal songs that were played to it.
Yet despite this bird’s seemingly solitary and silent life and bizarre appearance, Professor Peer and Mr Motz never observed its flock mates behaving aggressively towards it.