Often I find pictures in my E-mail box with the question to give a name to the birdvariety. I will discuss a recent example. I got two nice sharp pictures from a bird fancier in France. He bred two Bourke's. I was allowed to show them in my web-site. I want to tell you what my idea was about this birds.
The information I received was: "These are probably two Bourke's hens, The left one is dark. The right one is a normal wildtype".
It is difficult to say something about "variety" or "mutationfactor" when the picture shows only a part of the wings of both Bourke's. But I tried to give a first impression.
1. Both Bourke's are cocks. The brown colour of a hen is much duller brown. The pattern of wingcoverts of hens and cocks is different. The kernel and margins of the wing covets are much sharper marked off.
2. The wing coverts are dark brown. The brown inner part of these feathers is darker than normal in both birds. This is different compared with the wildtype Bourke.
3. The margins of the wing coverts are green.The green colour of the margins of the wing coverts is abnormal, because the margins of the wing coverts in the Bourke's parrot are always yellowish or white, never green or blue.
4. Both Bourke's have same coloured wing coverts.
5. I cannot call the blue colour of the left Bourke dark blue and the blue colour of the right Bourke normal. There is certainly a difference between the blue colour on the shoulder and the flights of both Bourke's. I call the colour of the left bird violet and the colour of the right bird cobalt blue.
Some first conclusions: This picture shows definitly two cocks with a much darker plumage than normal. It could be a variety with a violet factor. The fact that all colours are more shining than normal could supports this idea.
I asked the owner for a more complete picture. He was so kind to send me two new photo's, one of the undertail feathers, one of the heads.
This picture shows clearly the under tail coverts. The colour of the under tail coverts of the left Bourke (in the upper position) is definitely violet . There is a difference between the two Bourke's. In the Bourke in the down position we see a cobalt colour. We see a much more dark plumage also. When we combine this with the colour of the shoulder and the wing, we can conclude that one cock (left, up) has a dark factor and a violet factor, the other cock (right, down) has a dark factor.
The head studies on this new picture shows that I was right when I supposed that both Bourke's are cocks.
Also there is an extension of the blue colour in the cheek and in the flights of the two Bourke's. Maybe there is is a light blue or green suffusion on the back of this birds too. I have no picture of the back to verify this. In my web site I presented earlier two pictures. One shows a dark wild-type cock with a violet factor. An other picture shows a dark wild-type cock , with a green suffusion on the back. I am breeding regularly some of this beautiful Bourke's. Especially this variety with a violet factor is a very beautiful new variety.
Boris I thank you for sending me this pictures of yours. I hope you have a lot of success with this nice Bourke's in the coming breeding season .