The green honeycreeper, belonging to the bird family Thraupidae, stands out as a captivating and diminutive species of tanager.
This avian species is not only widespread but also readily noticeable across its habitat, stretching from southern Mexico to southeastern Brazil. Its diet primarily consists of nectar, fruit, and insects, and it often frequents feeders that provide fruit.
The plumage of the green honeycreeper is notably sexually dimorphic. Females showcase a grass green hue, slightly lighter on the underside, while males exhibit an aqua blue coloration with a distinctive black hood, mask, and chin. The bill color also displays sexual dimorphism, with males having a vibrant yellow mandible and lower maxilla, complemented by a black culmen, while females sport a subdued yellow mandible and a black maxilla. Juveniles closely resemble females.
Despite the marginal variation in wing and tail lengths between males and females, considerable overlap and no significant mass difference exist within each sex.
In a rare occurrence of bilateral gynandromorphy, a green honeycreeper displaying both male and female characteristics on different sides was observed at a feeding station in Villamaría, Colombia, between October 2021 and June 2023. Bilateral gynandromorphy is a condition where one side of the organism exhibits male characteristics, and the other side displays female traits.
Professor Hamish Spencer and his colleagues from the University of Otago explained that this phenomenon is known in various animal groups, especially those with sexual dimorphism. In birds, it is believed to result from an error during egg meiosis, followed by double fertilization by separate sperm. Consequently, one side of the bird contains heterogametic (ZW) female cells, while the other side has homogametic (ZZ) male cells.
This instance marks only the second recorded example of gynandromorphism in the green honeycreeper in over a century. Professor Spencer emphasized the rarity of such occurrences, highlighting the significance of the find and praising the exceptional quality of the photographs, which he deemed the best of a wild bilateral gynandromorphic bird of any species. The discovery holds importance for advancing our understanding of sex determination and sexual behavior in birds.