Half rooster, half hen
Despite their hybrid exterior the animals have only one set of reproductive organs. The hen-roosters either had testes or ovaries. The researchers did not test whether the animals can reproduce normally.
Gynandromorphy also occurs in other bird species, such as pigeons, zebra finches and parrots. The researchers expect that it occurs in all bird species, but that it is not detected in species where the female and male look very similar. Also in other animal species gynandromorphy occurs, such as in butterflies.
Note that a hermaphrodite is completely different from a gynandromorph. A hermaphrodite is entirely functional as both a male and a female. This is not a mistake of nature, but an ‘official biological blueprint’. Freshwater snails and rain worms for example are hermaphrodites.
The rooster in the picture is not a gynandromorph.