The bilaterally gynandromorphic Green Honeycreeper found near Manizales in Colombia. Photo: Supplied / John Murillo
The sighting of an extremely rare, half-male, half-female bird, is being celebrated by an University of Otago zoologist.
Professor Hamish Spencer was on holiday in Colombia earlier in the year when a wild Green Honeycreeper was pointed out to him.
It had distinct half-green and half-blue plumage, and was only the second of the kind spotted in more than a century.
Spencer said the abnormality was caused by double fertilisation of the egg.
Only two birds of the kind have been seen in more than 100 years. Photo: Supplied / John Murillo
"Cells that are dividing to form the female egg haven't done it properly," he said.
"What happens is actually two cells get fertilised by the sperm, so there's 'double fertilisation' we call it. So two separate sperm fertilised two different cells that become the two halves of the bird."
Spencer said many birdwatchers could go their whole lives and not see a bird with both male and female characteristics, known as gynandromorphs. His photos were "arguably the best of a wild bilateral gynandromorphic bird of any species ever", he said.
"There's fewer than a hundred records across all species of birds ever, that we know about, that have been recorded," he said.
"I don't know of any examples from New Zealand at all."