A zoologist from the University of Otago in New Zealand spotted a rare bird with distinct half-male and half-female plumage. Hamish Spencer and amateur ornithologist John Murillo took photos and video of a wild green honeycreeper (Chlorophanes spiza) while on vacation in Colombia. A report on the find was published in the Journal of Field Ornithology and represents the second recorded example of gynandromorphism in this species in more than a century.
[Related: These female hummingbirds don flashy male feathers to avoid unwanted harassment.]
A bilateral gynandromorph is an animal that is born with one male half and one female half. The animal is usually divided down the middle with characteristics of two sexes in one body. Bilateral gynandromorphism has been documented in other animals including bees, butterflies, spiders, and stick insects. Cardinals and the rose-breasted grosbeak have also been documented with this division, but bilateral gynandromorphs are believed to be rare.
“Many birdwatchers could go their whole lives and not see a bilateral gynandromorph in any species of bird. The phenomenon is extremely rare in birds, I know of no examples from New Zealand ever,” Spencer said in a statement. “It is very striking, I was very privileged to see it.”
Studying gynandromorphs are important for our understanding of how biological sex is determined in birds and their sexual behavior. Male green honeycreepers have predominantly blue plumage. Female green honeycreepers have green plumage. The observed bird has both.
“This particular example of bilateral gynandromorphy–male one side and female the other–shows that, as in several other species, either side of the bird can be male or female,” said Spencer.
While there are a range of theories of how gynandromorphic animals form, scientists believe that it could occur in birds when a female egg cell…
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