growing host of new and exquisite Cockatiel color mutations and their myriad combinations are impacting Cockatiel circles both on and off the show-bench at a challenging rate. With such "rares" of yesterday now increasingly spotted at bird fairs, formally inscribed within show class ific a ti ons, and currently rooted throughout classified advertisements, the contemporary list of new mutations continues to grow.
No longer are breeders confined to a world of a few simple sex-linked or autosomal recessive mutations. Now, the art of producing and combining such color combinations requires as much forethought as the painter's use of the palette. While some mutations may continue to mystify both the newcomer and veteran breeder, a few simple principles may provide insight and a clearer understanding of how such colors and patterns routinely operate.
Whenever instructing Cockatiel genetic workshops, I frequently recommend fanciers approach the subject by considering the big picture. Such an overview of genetic modes of inheritance, classifying mutations into subsets, or categories, often provides a rudimentary grasp, or "feel," for working with these mutations, understanding their basic strengths and weaknesses, and the manner in which they may be inherited.
This article series will focus on the standard varieities and current rares as set forth in the nomenclature commonly employed by U.S. breeders in both the American and National Cockatiel societies. While additional Cockatiel organizations are
currently forming around the globe, with many adopting their own show standards and nomenclature, the U.S. organizations have been in existence for nearly two decades, with classifications stretching as far back as the late-seventies and early eighties.
Dominant Mode of Inheritance
In Cockatiels, we have at present two distinct, dominant colors to consider. The first and more familiar is the nominate race, or wild Cockatiel of Australia, commonly referred to as the Normal Gray. In recent years however, the Dominant Dilute, more popularly known as the Dominant Silver, was bred in the United Kingdom. The Dominant Silver has the distinction of being the first dominant mutation ever to occur in Cockatiels.
Until very recently it was an accepted fact that all Cockatiel mutations were recessive to the Normal Gray. With the exception of the new Dominant Silver mutation, this rule remains true even today and no other color may dominate all resulting offspring produced whenever a Normal Gray is utilized, regardless of parental gender.
However, whether Dominant Silvers are currently available here in the U.S., or become available to breeders in the near future to produce the mutation in enough quantity for prices to drop, only time will reveal. I do believe, however, there is a strong likelihood we shall see other dominant mutations in the future, which should lend an even greater variety to the delightful color combinations
we are already beginning to see in representative numbers at shows, exhibitions and fairs.
As the nominate wild type Cockatiel, the Normal Gray may be described as a solid gray bird, with white wing-bars, and carotenoid orange and yellow pigments coloring ear convert feathers, head and undermarkings. Males carry the full yellow face mask upon maturity, often with a deeper intensity to the orange ear covert feathers, which are more commonly referred to as the orange "cheek patch."
Although lacking the full yellow face mask, hens and unflighted young do carry some degree of yellow on the face, typically marking areas around the forehead, lores and beneath the lower mandible. Yellow spotting on the undersides of flight feathers, and yellow barring under the tail, are carried by both hen and young, while solid gray tail and flight feathers distinguish the adult males.
While some Normal Grays do vary in their intensity of dark factors, demonstrating shades of light, medium and very dark gray, it is not at all unusual to find variations of color depth within the same individual. Such variations within the same bird, however, are discouraged by National Cockatiel Society show standards, rewarding instead an even tone throughout the bird regardless of the presence or absence of dark factors.
Therefore, such an individual, be it either a solid light gray, a medium gray or a dark gray would be equally desirable, as long as the shade of gray remained consistent throughout. In contrast, during recent years the American Cockatiel Society revised its show standards, specifying all Normal Gray should be colored dark gray, while ideally carrying a uniformity of color throughout.
During the early 1980s, the Dominant Silver made its appearance in the United Kingdom, originating in the aviaries of Mr. Terry Cole. As presented above, the Dominant Silver has the distinction of being the first, and only, dominant mutation in Cockatiels, and the first Cockatiel mutation to be produced by the United Kingdom.
By 1988, Cole bred the Dominant Silvers into many of the color varieties
including the Whiteface, which he has termed the combined form as Platinums. This could cause some confusion in international circles as there are already some U.S. breeders who refer to the Fallow-Recessive Silver, a double-recessive cross mutation, by the same name.
Interestingly, the Dominant Silver comes in two forms, the single-factor (SF) mutation, and the double-factor (DF) or dilute form. Single factor Dominant Silvers appear as a pastel-silver shade of gray, with a deeper shade coloring the area of the head and neck, creating the unique appearance of a "skullcap." In addition, true Dominant Silvers carry black eyes and dark gray legs, which easily distinguish them from the Recessive Silver mutation, which has dark plum to red eyes, lighter feet and a color range of steel or silvery gray, to fawnish brown.
Although indistinguishable upon hatching, Dominant Silvers can soon be identified from Normal Gray siblings once they start to feather, by their light gray, brownish-brick body color. In addition, the darker skullcap, dark gray pigmented legs and black eyes will already be evident.
Interestingly, after the first juvenile molt, cock birds acquire the more silvery gray plumage, while hens maintain their original color, although perhaps a bit brighter, and grayer. Over the years, Cole has succeeded in selectively breeding hens which are much lighter and therefore more similar to cock birds. Currently, however, Dominant Silvers in the U.K. vary quite a bit in their dilution of gray melanin, especially in single-factor birds. The similar goal of breeding for a consistent shade or depth of color, is recommended.
Double factor Dominant Silvers are a dilute form of the single-factor variety. Such birds appear almost as light as a Lutino, with the addition of a subtle light gray wash throughout. Once again, double-factor Dominant Silvers carry the darker skullcap, dark legs and black eyes. of their single-factor counterparts.
Cole, Terry, 1988. "Firsts with the Dominant Silver Cockatiel," Cage and Aviary Birds, United Kingdom, August 13, p.2.
Reed, Nancy A., 1990. "ACS Show Standard,"American Cockatiel Society Standard of Perfection for Exhibition Cockatiels, (revised)
Rubin, Linda S., 1984. "NCS Show Standard of Excellence," National Cockatiel Society Magazine and National Cage Bird Show 1984 show catalog.
Rubin, Linda S., 1991. "New Dominant Silver Mutation of Europe," The A.F.A. Watchbird, American Federation of Aviculture, Phoenix, AZ, Vol. XVIII, No. 1, Feb/March, pp. 21-23.
Rubin, Linda S., 1990. "True Mutations Can Be Exciting," Cage and Aviary Birds, United Kingdom,April 14,pp.17-18.