How many of you remember back to science class to when we were taught about chromosomes? As a quick refresher, genetic males will have a differing set of chromosomes in the form of XY and genetic females will have two of the same type of chromosomes in the form of XX. Birds, like everything else they do, follow the beat of their own drum. Scientists notate bird chromosomes with W and Z instead of X and Y. It’s the genetically male birds who have two of the same form chromosomes (ZZ) and it’s the females that have a differing pair of chromosomes in the form of WZ. Since in some species color is linked to which set of chromosomes a bird has, this can show us some interesting examples of gynandromorphy and chimerism. In the Eclectus Parrot below, the egg cells its mother produced accidentally fused early in development, resulting in a single bird with both male and female cells and chromosomes: https://i.redd.it/yaotjacj2xb41.jpg
Another interesting example is this budgie named Twinzy. He is an example of a tetragametic chimæra where two brothers with different color genes fused early on: https://i.redd.it/ak5p2vk92bv81.jpg
Genes can sure make things interesting!