Recently photographed bird of both sexes is half-blue, half-green

The female Green Honeycreeper bird is appropriately enough colored green, whereas the male is blue. So, what happens when a Honeycreeper is half of each sex? Well, as recently taken photos show us, the bird is blue on the right and green on the left.

The remarkable photographs were taken by amateur ornithologist John Murillo, at the Demostrativa Don Miguel Reserva Natural near the city of Caldas, Colombia. On various occasions between October 2021 and June 2023, the animal had been sighted at a feeding station in the area that supplies fresh fruit and sugar water to the local birds.

Murillo brought the unique Honeycreeper to the attention of Sesquicentennial Distinguished Professor Hamish Spencer, who is a zoologist at New Zealand's University of Otago. Spencer got to see and study the creature for himself, as he was holidaying in Colombia at the time.

The bicolored bird is a rare example of what's known as bilateral gynandromorphy, a phenomenon in which one side of an organism exhibits male characteristics while the other exhibits female characteristics.

It's seen in a large number of animal groups, particularly those that are sexually dimorphic (which basically means, the two sexes differ significantly in appearance). In birds, the cause is believed to be an error during egg meiosis (cell division) followed by double fertilization by two separate sperm.

This is only the second recorded example of bilateral gynandromorphy in a Green Honeycreeper (Chlorophanes spiza), the previous report dating back to 1914. And in that case, it was blue on the left and green on the right.

Because this latest bird wasn't captured, it's impossible to know if its internal organs are both male and female. Such is likely to be the case, however, since when a number of previously collected bilaterally gynandromorphic birds (of other types) were dissected, they were found to have an ovary on one side and a testis on the other.

The bird's observed behavior was fairly normal for the most part, although it did tend to avoid other Honeycreepers, and they avoided it. One has to wonder, though … is it able to reproduce?

"Other gynandromorphs have done so, but others have not," Prof. Spencer told us. "Our bird was never seen as part of a pair, so my guess (and it is just a guess) is probably not."

A paper on the research was recently published in the Journal of Field Ornithology.

Source: University of Otago