Abstract
In the April-May 1977 issue of the AF A Watchbird, R. Smith gives a very fine account of his successes with the yellow Bourke mutation. One problem with the article, however, is that it doesn't tell us if two different strains of yellow Bourkes really exist, and if so what the differentiating characteristics are in terms of color and genetics.
European breeders are now generally agreed that there are two distinct yellow Bourke mutations. One is referred to as a yellow Bourke and the other a cinnamon. (The existence of a true lutino has also been rumored but has not yet been confirmed or documented in the literature.) The yellow Bourke is definitely a recessive mutation while the cinnamon is sexlinked. When the first birds were imported to the U.S. no one was quite sure what mutations they had acquired and it wasn't long before the two strains were hopelessly mixed together. The results are confusing to say the least and it is no wonder that each breeder of the mutation Bourkes seems to have rather different results arriving at few clear-cut answers.
The fact is that the two mutations are easy to identify and I would urge that those who breed Bourke mutations take a close look at what they have.
The color of the eyes of both mutations is basically red and hence gives little help in the identification process. Even the feather coloration of the two mutations can be so similar that a clear differentiation is impossible. Only the very light colored yellow Bourkes form an exception - they are predominately of the yellow, recessive type. Some yellow strains in Europe are now already so perfected that the yellow is quite spectacular.
The easiest signs for identification are the toenails and the beak. On a true yellow Bourke mutation the toenails as well as the beak are light flesh colored, while the cinnamons have dark toenails and a somewhat dark beak ( though not as dark as the normals). One statement of caution is m order here: don't confuse the toenails with the toes. The toes of both mutations are flesh colored; it's only the nails that give us the real clue.
Breeders who have recognized these differences in their birds have verified the fact that two distinct mutations exist. This discovery has led to better line breeding as well as a better yellow strain among the yellow Bourke. Finally, the separation of the two mutations will also give us more predictable results, which in turn will give more confidence when trading or selling your birds.
To summarize, the yellow recessive Bourke will breed exactly like all other recessive mutations and the guidelines which Mr. Smith has presented in his article are therefore valid. Cinnamons on the other hand are sex-linked and hence breed like white or cinnamon cockatiels and like most other lutino or albino mutations. Remember that in sex-linked mutations you cannot have a split female while in recessive mutations you can. This alone makes it imperative that you...