Yellow and red pigment

This picture shows a Rose opaline-pastel cock, and two young Bourke's parrots. This male was mated to a Blue opaline hen. The results are Yellow opaline, Blue opaline and Rose opaline. This is an important picture. The young Bourke's show a yellow back. This is peculiar. The yellow opaline color variety of the Bourke is seldom seen in the aviculture.

Discussion: Most breeders think that the combination of opaline characteristics and yellow pigment is impossible. This is reasonable because since the first Rose opaline Bourke came into being in 1972 breeders were selecting to become the most solid rose colored specimen. Later on they combined the Rose opaline variety with the Fallow variety and in this way a beautiful rose Bourke was the result. One of the most important questions is: Is it true that there is a connection between the mutation factor M-di (di- means distribution of melanin) that causes the opaline characteristics and the extension of red pigment P-ir (ir means increase red) what we see in the Rose opaline Bourke?

The mutation factor that caused the opaline variety is definitely a melanin factor (M-factor). In the Budgerigar this mutation factor caused a change of the distribution of black melanin in a part of the wing feather pattern and the undulation pattern of the hind-neck and the upper back (the saddle). Melanin in the cortex of a feather is replaced by psittacine pigment. We see this in the Opaline variety, in the Edged variety and in one of the Pied varieties. In the Pastel variety we see that a decrease of the melanin the yellow pigment is coloring the back. In the Lutino and Rubino variety the melanin is complete dropped out. The conclusion is that in all this varieties the loss of melanin is accompanied by a extension of the psittacine pigments, red or yellow separate or in combination.


Young Yellow opaline Bourke before the first moult

Description: The upper back is yellow. There is a remnant of red pigment .The crown is yellow. In the hind neck there is a mixture of red and yellow. The upper tail coverts are blue, mixed with yellow. The margins of the tertiary wing feathers are green. The tail feathers are blue-green. In the outer side of the primaries there is a blue-white spot. The eyes are dark.

Discussion: What is the relation between the formation of red and yellow pigment. The first idea was that the difference was the amount of the same psittacine pigment. A new and better idea is that there are two different psittacine pigments. Research about the psittacine pigments turned out that both pigments have a different chemical make up. (Stradi(2001, MacGraw &Mary Nogare 2005)

Relation between red and yellow pigment: In my classification of psittacine mutations I describe the P- mutation factors. Shift in proportion of both pigments. Strong increase of the yellow pigment or the red pigment. We see this in the yellow and the rose opaline and ino varieties.

Yellow opaline Bourke after the first moult

On the left side we see the same yellow opaline Bourke after the first moult. There is a little bit more red pigment in the head and the back. The wing coverts are margined with yellow. This yellow opaline Bourke is split to the pastel- and the blue mutation factor. The eyes are dark. The yellow opaline is a rare variety.

Copyright 2005 by Bob Fregeres

E-mail: fregeres @bourkes-parakeet.nl


5/11/06