Description: This picture shows a red opaline and a yellow opaline Bourke. The yellow opaline is a cock. The head is yellow brown and white. The hind neck, back and wings are yellow. The tail is partly yellow partly green. The rump is green. The outside of the wing and the end of the tail are dark brown. The margins of the greater wingcoverts are greenish yellow. The eye is dark. The horn parts are normal like the wild-type Bourke.
Development: The father was a beautiful yellow pastel. The mother was a blue opaline. This hen had a grey head, a green and blue upper and lower back , partly blue wings and a blue rump. The mixture of green and blue colour of the back was interesting to me. This means that this hen had some yellow pigment in the feathers of the upper and lower back. The father was a bright coloured yellow pastel (Y-3), split for opaline. The result was a new colour variety in the yellow series. I bred this bird in 2002.
Beckmann wrote that the red and yellow pigments in the wild-type Bourke are mixed . In this yellow opaline Bourke there is a separate reduction of the red pigment in the back, rump and tail. The melanin distribution factor (M-d factor) that causes the opaline colour variety is inheriting independently from the red and yellow psittacine factors (P-factors). When we compare this yellow opaline with the wild-type the reduction of the eumelanin on the back is nearly complete. Only some little dark stripes on the back are visible. This reduction made it possible that the rich yellow colour could show up. The yellow colour of this opaline is comparable with the yellow colour of the pastel hen, the yellow edged cock and the lutino. Three qualities worked together, this yellow opaline cock got the yellow pigment of the father, the loss of red pigment of the mother and reduction of the eumelanin from the opaline.
Name: The name yellow opaline is the best name for this colour variety. Yellow is the reference colour. The white triangle in the wing, the fine stripes on the back and the specific distribution of the melanin are indications of the opaline. By this yellow opaline the five colour series: the white-, red-, yellow-, blue- and green series of the opaline are complete.