Nature is full of surprises and the sighting of an incredibly rare bird in Colombia has highlighted the beauty that can arise from genetic mishaps.
Otago University Zoology Professor Hamish Spencer had the privilege of sighting an incredibly rare bird that is both male and female, called a bilateral gynandromorph, while on a "bird watching holiday" in Colombia.
The striking Green Honeycreeper has half-green and half-blue plumage, an incredibly rare phenomenon in birds.
Spencer told Newshub, while in Colombia, he saw over 560 species of birds, more than 5 percent of the world's total species.
Colombia has more species of bird than any other country, in part due to its elevation which results in tall mountain ranges and the often-isolated species living in relative peace.
"There's a lot of endemic species that occur only in Colombia," Spencer said.
Spencer was shown the bird by John Murillo, a farmer he described as "keen on birds who runs a local eco-tourism business in the Colombian countryside because he's preserving some forest on his land".
Murillo first discovered the bird, took footage of it, and led the investigation into the bird.
"These photos are the best of a wild bilateral gynandromorph ever," Spencer said.
"They're just so clear and it's a pretty rare phenomenon," he said.
Spencer estimated the number of recorded cases across equivalent species to be less than 100 throughout history.
There are no examples of such a bird in any species in New Zealand.
"I was really really privileged than John shared it with us," Spencer said.
"I knew it was special because I'm a biologist, but I didn't realise quite how special it was at the time."
Spencer described bilateral gynandromorphy as "a developmental accident, something has clearly gone wrong".
While scientists do not know for sure what happens to cause the aberration, they are pretty sure it is caused by an error in the process of cell division when the female egg is being formed.
"There are two sperm that fertilise what goes on to become the bird," Spencer explained.
"There's two cells instead of one in the egg and they both get fertilised by different sperm and they both end up with two different types of chromosomes."
When it develops from there, one side of the bird turns out female, and one side turns out male.
This theory of how bilateral gynandromorphy occurs is called double-fertilisation and is supported by the fact that the female plumage on this Green Honeycreeper was on the other side to the one spotted in 1914.
Because the bird had not been captured and dissected, scientists have been unable to discern the makeup of its internal organs, "and so we don't know whether it had ovaries on the left and testes on the right," Spencer said.
"That's probably the case, but we don't know," he said, and this has been observed in other examples.
When bilateral gynandromorphism has happened in other species of bird, there have been examples where they successfully breed.
However, it's suspected the Green Honeycreeper that Spencer saw has not reproduced because there has been no courtship behaviour or pairing with another bird observed.
A report on the find called "Report of bilateral gynandromorphy in a Green Honeycreeper (Chlorophanes spiza) from Colombia", has been published in the Journal of Field Ornithology.
The journal article on the bird observed "The gynandromorph usually waited for the other honeycreepers to leave the feeders before landing to feed itself.
"In general, it avoided others of its species, and the others also avoided it; it seems unlikely, therefore, that this individual would have had any opportunity to reproduce."
Spencer said this was significant for his field of study "because it documents a really interesting case and scientifically supports the theory of fertilisation by two different sperm".
"For me personally, I'm just really privileged to have seen a bilateral gynandromorph because most bird watchers will not see one in their whole life, of any species."
