Green opaline (G-5)
Description: This picture shows a green hen and a green young. The hen has a blue frontal band, just like a cock. The shoulder shows some blue. The wings are green with a black out side. The beak is black. In the lower back some red spots are seen. Careful observation learned me that this feathers are green with a red tip. The rump is light sky blue mixed with some green. The tail is blueish grey. The eyes are dark.
The back, rump and part of the wings of the young are green.completely. The wing coverts are black with a broad green margin. The young has also a blue frontal band. But it turned out that this young is a hen. This green of the young and her mother is very remarkable, because the wildtype Bourke has no green in the plumage, not a single feather. Green is a total new colour variety of the Bourke.
Green is a sign that there is a blue structure in the feather. The green colour is a combination of a blue structure in the feather and yellow pigment in the cortex. Originally in the hind neck, the back and the wing coverts of the wild type there are no feathers with a blue structure. This are feathers of the common type, without a sponge layer under the cortex. A blue structure in the featherbarbs in this fields is new. Feathers of the common type became feathers of the structural type, with a blue structure. The combination of the new blue structure in this areas with yellow pigment gives the green colour. In the hind neck of the young we recognise this yellow pigment as a yellow collar.
Name giving: I named him green opaline. The reference colour is green. This colour differs from all the other Bourke colour varieties and the wildtype. The opaline characteristics are not easy to discover in this picture. Two characteristics are visible. The dark outside of the wing and the bright coloured back. This is a sign of another distribution of melanin in the plumage. An other opaline characteristic is the fine dark striping on the back
Development: Green is the result of a combination of the blue structure in the feathers and yellow pigment. Because some birds in my blue strain of Bourke's showed some green I tryed to strenghten the amount of yellow pigment. There are several possibilities. Mating with yellow pastel is obvious, but also via a carefully selected wildtype we can reach the same result. In the wildtype we have to inspect the margins of the wing coverts. We should use only wildtype's with clear yellow margins on the wing coverts. Now I have blue and green Bourke's. The combination of blue opaline with yellow pastel brought also a new development: the first light green opaline-pastel (G-53) appeared.