Pied Bourke's parakeet (W-7)
Description: Pied is caused by the loss of melanin as we see on this picture of this pied wildtype cock. Most one ore more of the flights are white. In this Bourke the third feather of the primaries is white. The brown eumelanin is lost in the shaft and both vanes. All brown melanin is gone. The result is that the blue structure can not show the blue colour because of the lack of eumelanin in the centre of the barbs. The whole contour feather is white till the quill. In this picture some feathers of head, wing ,back and some tail coverts are missing the eumelanin. When in this feathers red or yellow pigment is present this become visible. This makes clear that pied is a melanin mutation. This Bourke has but little red and yellow pigment. Only a little bit in the head, back and tail. This is mixed with a little bit of yellow. The pied wingcoverts are mainly white. The pied pattern is irregular.
Development: Thus fare pied Bourke's are turned up in some places. Most this pied was not inheriting. In cases that this pied pattern was inherits from the parents, the inheritance turned out to be recessive. So far I know nobody in Holland has developed a strain of this birds. The recessive pied mutation factor can be combined with all other colour varieties. A nice pied is a pied with strong colour contrasts, like the wildtype pied and, if possible a more regular pied pattern.
Name giving: The proper name of this Bourke is white pied. White is referring to the colour, pied refers to the characteristics of the eumelanin. When the bird has a lot of red pigment red pied is a proper name. The cause of a pied plumage can be found in the shortage of germ cells according to Kop. In fact it is a distribution problem of the eumelanin germ cells. There is a shortage of germ cells by mutation that should have moved from the neural crest to the skin. This is the reason that not all follicles can develop melanin production cells. This can happen in all kinds of feather types, flights, tail feathers, etc. inclusive the down feathers. This happens in a very early stadium in the embryo.