Blue opaline Bourke
Description: The picture shows a blue opaline Bourke's hen. The eyes are dark. The head is grey. There is a blue frontal band! The bill is brown with a black stripe. The breast is dark rose and grey. The upper back is light sky blue with a little bit of green. There is a little bit of rose seen in the upper back and wing. The shoulder is sky blue. The bend of the wing is cobalt blue. The wing is partly dark brown or black. The wing coverts are dark, margined with blue and white. We see a white patch on the flights, caused by a broad under wing stripe. The dark wing feathers give a nice contrast with the white patches on the flights. The lower back and rump are sky blue. The tail is blue. The hips and under wing coverts are blue. The tips of the tail are black. The nails are black.
Name giving: A proper name of this colour variety is blue opaline Bourke. The reference colour is blue. The blue back, rump and tail, are the most striking differences with the wildtype. Opaline is not a colour name any more. The term opaline is representing a group of characteristics of the melanin. Three characteristics are present: More melanin in the feathers of outside of the wing, less melanin in the mantle and the back (1), the white triangle in the bend wing, caused by the broadening of the under wing stripe (2) and the fine striping on the back, a remnant of the dark coverts of the wing and the back (3).
Development: I developed a strain of blue and green Bourke's. The mutation took place in the opaline Bourke. From a pair of rose opaline I bred in 1997 two beautiful blue hens and a split cock. This first blue birds I mated with the parents and wildtype Bourke's. To do my developing job successfully I had to understand first the dynamics of this blue colouring.
Nobody could expect such a extension of the blue colour in the plumage as found in my Bourke's.
I found the lead to the explanation of the new blue colour variety in the research of the Technical Commission of the N.B.v.V. (1973) of the feathers of the brown Bourke and a few colour varieties of the Bourke. Beckmann did research into the feather structure of the Neophema and the Bourke. He was writer, bird fancier and member of this Committee He made difference between feathers with a blue structure (structural type) and feathers without this structure (common type). I found the solution reading his careful investigation of the plumage of the Bourke. All the feathers that changed the colour from rose to blue were feathers of the normal type, without a blue structure.
The extension of the blue colour in the whole plumage is only possible by a change of the feather structure of the feathers of the back, part of the wings and tail feathers. Feathers of the normal type (without blue structure) have to be changed in feathers of the structural type (with blue structure).
I found that this new factor is inheriting recessive. This factor (S-factor) is inheriting independently of the M-factors of the opaline and the pastel colour varieties.
This helped me to understand the dynamics of the new mutation factor and to realise in praxis the development of a healthy strain of blue and green Bourke.