Additional information was added on January 18, 2013 at: Punnett Squares for Bourke Coloration
Normal or wild color refers to the natural or baseline genetics/coloring of the birds in the wild. Mutations alter the baseline appearance of the birds from normal/wild colors.
For birds, similar to humans, there are 2 copies of each autosomal chromosome on which the genes exist, so there are 2 copies of each gene. There are also the sex chromosomes that determine the gender of the bird. In contrast to humans, the male bird has 2 copies of the same sex chromosome called the Z chromosome (ZZ) and the female bird has 1 copy of the Z chromosome and 1 copy of the W chromosome. For the mutations that exist on the Z sex chromosome, the male bird can have 2 copies of these mutation genes while the female bird can only have either 1 copy or none.
Another concept that is important to grasp is dominant or recessive. A gene that is dominant will show up even if only 1 copy of the gene exists in the bird. If a gene is recessive, there needs to be 2 copies of the mutation gene in the bird in order for the mutation to show up.
The term “split” applies to the recessive genes when the bird only has one copy of the mutation gene. Since it doesn’t have 2 copies of the recessive gene, it will not physically show the mutation, but it carries the hidden mutation gene that can still be passed to its offspring.
|Note Normal male at left has brighter colors |
than Normal hen on right. © Gail Lewis
|Bronze fallow male: ©Su Yin|
|Pale fallow male: ©Su Yin|
|Pale fallow hen: ©Su Yin|
| Photo by Atholl Shelton (Australia).|
Sex-linked recessive mutations:
|Cinnamon Bourke: |
Lutino Bourke ©Su Yin
|Opaline males: ©Su Yin|
Below are examples of opalines with less pink and other colors. To the left is a blue opaline and the one on right is often called a rainbow.
|Blue opaline Bourke.|
Breeding and photo from A. Coljon.
Photo and bred by A. Coljon.
Combinations of mutations:
|Pink hen or opaline fallow hen: ©Su Yin|
|Pink male or opaline fallow: ©Su Yin|
Opaline lutino: ©Su Yin