The rare half-female, half-male bird spotted in Colombia – 01/03/2024 – Science

A very rare meeting took place in Colombia.

Amateur ornithologist John Murillo was in the Don Miguel Demonstrative Natural Reserve, about 10 km southwest of the city of Manizales, Colombia, when he saw something that caught his attention: a wild tanager bird, also known as a tem-tem, or Chlorophanes spiza.

But there was something absolutely unique about that bird: on the left side the plumage was green, a color characteristic of females of that species, and on the right side the plumage was blue, typical of males.

Murillo had just made a discovery.

“It was extremely exciting. It’s likely that most birdwatchers will go their entire lives without seeing a gynandromorph, so I was privileged to benefit from John’s discovery,” he tells BBC News Mundo (BBC’s Spanish-language service) Evolutionary geneticist Hamish Spencer, professor in the Department of Zoology, University of Otago, New Zealand.

Spencer also saw the bird because he was on vacation in Colombia at the time.

The phenomenon, he says, is extremely rare in birds. In fact, he doesn’t know of any examples in New Zealand.

A very unique condition

Bilateral gynandromorphy is a condition that causes one side of an organism to have male characteristics and the other side to have female characteristics.

This is what Spencer points out in the article Report of bilateral gynandromorphy in a Green Honeycreeper (Chlorophanes spiza) from Colombia (Report of bilateral gynandromorphy in a green tanager (Chlorophanes spiza) from Colombia), from the specialized ornithology publication Journal of Field Ornithology, which was written with other authors, including Murillo.

The phenomenon “is known in a large number of animal groups, most frequently in those in which there is sexual dimorphism [nos quais é mais facilmente detectável]”.

This finding is the second example of gynandromorphism recorded in the species in more than 100 years.

“The gynandromorphs [animais com características masculinas e femininas numa espécie que geralmente têm sexos separados] are important to our understanding of sex determination and sexual behavior in birds,” says Spencer in a statement from the University of Otago.

But what does this unique bird tell us about the animal world?

“Sexually dimorphic plumage in birds is due to the chromosomal composition of nearby cells, and not to any hormonal differences throughout the body,” he explains to the BBC.

The condition had already been detected in insects, mainly butterflies, crustaceans, spiders and even lizards and rodents.

“This particular example of bilateral gynandromorphy [macho de um lado e fêmea do outro] shows that, as in many other species, any side of the bird can be male or female”, says the professor in the statement.

The researcher highlights that the phenomenon “results from an error during the female’s cell division to produce an egg, followed by double fertilization by two sperm.”

21 months of observation

In the Don Miguel Demonstrative Natural Reserve, which is a farm with large areas of secondary forest, a bird feeding station was created.

There, the animals are supplied with fresh fruit and sugar water — and it is excellent for bird watching.

“At these feeders it is common to observe numerous species, as well as parrots, thrushes and euphonias in mixed flocks”, indicate the authors in the article.

The single bird that captivated them “was present for at least 21 months, and its behavior largely coincided with that of other C. spiza wild, although I often waited for them to come out to feed on the fruits that those responsible for the place placed daily”.

And at one point “he was territorial and did not allow other individuals of his species to approach those responsible for feeding.”

Researchers have no explanation for this specific behavior.

“It generally avoided others of its species, and others also avoided it. Therefore, it seems unlikely that this individual would have had any opportunity to reproduce.”

The truth is that, with or without heirs, this bird has already left a mark on the animal kingdom.