The green honeycreeper is a very attractive small species of tanager in the bird family Thraupidae.
This bird is common and conspicuous over its range from southern Mexico to southeastern Brazil.
It feeds largely on nectar, fruit, and insects, and often frequents feeders supplying fruit.
Its plumage is strikingly sexually dimorphic, females being grass green, slightly paler underneath, whereas males are aqua blue with a black hood, mask, and chin.
Bill color is also sexually dimorphic: males have a bright yellow mandible and lower maxilla, with a black culmen; females have a dull yellow mandible and a black maxilla. Juveniles largely resemble females.
Although males have, on average, slightly longer wings and tails than females, there is considerable variation within each sex and much overlap.
Similarly, there appears to be no significant difference in mass between males and females.
An extremely rare ‘half female, half male’ green honeycreeper — a phenomenon called bilateral gynandromorphy — was observed between October 2021 and June 2023 at a feeding station in Villamaría in the department of Caldas, Colombia.
“Bilateral gynandromorphy is the condition in which one side of an organism exhibits male characters and the other female,” said University of Otago’s Professor Hamish Spencer and colleagues.
“The condition is known in a large number of animal groups, most often those that are sexually dimorphic.”
“In birds, this phenomenon is thought to arise as a result of an error during egg meiosis, with subsequent double fertilization by separate sperm.”
“As a consequence, one side of the bird has heterogametic (ZW) female cells and the other homogametic (ZZ) male cells.”
This is only the second recorded example of gynandromorphism in the green honeycreeper in more than 100 years.
“Many birdwatchers could go their whole lives and not see a bilateral gynandromorph in any species of bird,” Professor Spencer said.
“The phenomenon is extremely rare in birds. It is very striking, I was very privileged to see it.”
“Photographs of the bird make the discovery even more significant as they are arguably the best of a wild bilateral gynandromorphic bird of any species ever.”
“Gynandromorphs are important for our understanding of sex determination and sexual behavior in birds.”
The team’s paper is published in the Journal of Field Ornithology.
Citation:
John Murillo et al. 2023. Report of bilateral gynandromorphy in a Green Honeycreeper (Chlorophanes spiza) from Colombia. Journal of Field Ornithology 94 (4): 12; doi: 10.5751/JFO-00392-940412.
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This article by Natali Anderson was first published by Sci News on 12 December 2023. Lead Image: A bilaterally gynandromorphic green honeycreeper (Chlorophanes spiza) near Manizales, Colombia, May 20, 2022. Image credit: John Murillo.
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