‘I couldn’t believe it at first’

It was the strangest sort of bird University of Otago zoology professor Hamish Spencer had ever seen.

In fact, he was in two minds about it.

But his eyes did not deceive him: the bird had the plumage of both genders.

Prof Spencer was holidaying in Colombia recently when his friend and fellow avian enthusiast John Murillo pointed out a wild green honeycreeper with distinct half-green, or female, and half-blue, male, plumage.

"I couldn’t believe it at first," Prof Spencer said.

"The plumage for the two genders are really distinctive, to the extent that people could confuse them for being completely separate species of bird.

"But here it was, a half-and-half split down the middle."

The last time a bird with both male and female characteristics, or gynandromorph, of this particular species had been spotted in the wild would have been more than a century ago.

"The bird we saw was female on the left and male on the right. The last recorded observation of such a specimen [of this bird] was male on the left and female on the right. So that’s really weird and interesting," Prof Spencer said.

Clearly something had gone wrong in the development of the bird, he said.

"What we think has happened is that in the process of cell division to form the egg, something hasn’t separated right.

"The theory is that there has been double-fertilisation which has occurred."

Asked about whether the bird would be able to reproduce, Prof Spencer replied: "the short answer is that we don’t know, because no-one was able to capture the bird".

"In most songbirds, females have only one ovary, whereas the males have testes internal on both sides. We don’t know whether this bird’s reproductive organs are fully functional."

Green Honeycreepers were "reasonably common" birds in Colombia and other South American countries, and liked to reside in the mountain ranges, Prof Spencer said.

"It’s a very wide-ranging bird, and not particularly rare. It often comes to bird feeders, but you can find it in places which have a little bit of forest."

Prof Spencer and Mr Murillo’s findings have been published in the latest edition of the Journal of Field Ornithology.

"I’m delighted that an enthusiast discovered this bird, and his photos were some of the best I’ve seen," Prof Spencer said.

The real challenge would be finding a gynandromorph among New Zealand species of birds.

"Of course, it would be a little hard to spot one. For tui, for example, males are bigger than females, but their plumage is the same. So would you notice them? Probably not.

"But the thrill of discovery is always there."

matthew.littlewood@odt.co.nz