Episode 75: Gynandomorphism in birds with Dr. Hamish Spencer

The sex of a bird – whether it is male or female – is one of the most critical aspects of its biology. Males and females often behave differently, especially during the breeding season, and in many species, they have strikingly different plumages.

This episode features Dr. Hamish Spencer, an evolutionary biologist at the University of Otago in southern New Zealand. Hamish was recently in Colombia, where he was shown a bird that violated these rules.

Colombian ornithologist John Murillo had discovered a very unusual Green Honeycreeper (Chlorophanes spiza) on his farm near Manizales in Colombia and pointed it out to Hamish when he visited early in 2023. The bird exhibited aqua-blue male plumage on its right and grass-green female plumage on its left. The bird’s head showed the black hood of a typical male on the right, but the left side was mostly green.

This episode discusses this bizarre phenomenon, known as bilateral gynandromorphy. How did it affect this particular bird? How does it arise? How common is it? Which species has it been observed in?

The article reporting this find has colour photos taken by John Murillo and is available at https://journal.afonet.org/vol94/iss4/art12/

John Murillo’s video can be seen at https://figshare.com/articles/media/DSCN2268_MOV/23739894