> “The phenomenon arises from an error during female cell division to produce an egg, followed by double-fertilization by two sperm,” he explains.
The bird is a chimera, with a different genome on each side of its body, one male (ZZ), one female (ZW).
Given we know the phenotype of this Green Honeycreeper has a male half and a female half, and given how incredibly likely that the mechanism is following established ways that chimeras occur, it is not hard to say with confidence that the male and female halves of the observed bird are almost certain to have distinct genotypes. Put another way, it would be a much more radical hypothesis that "this halfsider bird with two distinct sexes would not be a chimera."
Obviously we'd ideally wish to collect DNA samples from each side of the bird
That implies that there are no same-sex chimera birds running around undetected.