Yellowface II budgerigar mutation

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The Yellowface II budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. In combination with the Blue, Opaline and Clearwing mutations, the single factor Yellowface II mutation produces the variety called Rainbow.

Contents

Appearance

The single factor (SF) Yellowface II Skyblue variety is like a normal Light Green but has a very bright body colour midway between blue and green — a shade often called sea-green or turquoise. The body feathers of the SF Yellowface II Cobalt are bottle-green and in the SF Yellowface II Mauve they are a mixture of mauve and olive. [1]

The double factor (DF) Yellowface II Skyblue variety is very similar to the Yellowface I Skyblue, but the yellow pigmentation is brighter, and tends to leak into the body feathers to a greater extent.

Historical notes

Although not recognised as such at the time, it is possible that the first Yellowface II birds to be reported in the UK were bred by Jack Long of Gorleston-on-Sea in 1935. [2] A contemporary report [3] of his breeding says, "Mrs Lait mated a dark green cock to a greywing mauve hen, and in their third nest was a pale greywing mauve hen with a distinct (light lemon yellow) mask and bib, with the under tail feathers yellow and with yellow on the wings in the places where the normal blue bird is white. This hen ... was mated with a cobalt/white cock and they have produced five youngsters, all having yellow masks like their mother. Mr Long's birds were bred from a dark green of a somewhat olive shade mated to a rather unusually coloured hen, which appears to be a green but has a turquoise suffusion on the breast, etc. The first nest produced 3 cobalt birds with yellow masks, etc, like Mrs Lait's birds described above, and one green-blue bird like the mother. The second nest produced exactly the same result."

The description of the birds suggests that Mr Long's birds were a DF Yellowface II Cobalt cock and a SF Yellowface II Cobalt hen, but the breeding of Cobalts with yellow masks places this in doubt.

Genetics

The genetics of the several Yellowface mutations and their relation to the Blue mutation are not yet fully and definitively understood. [4] [5]

Much confusion and misunderstanding have arisen because the popular names given to these mutations are misleading. These mutations do not generate a yellow face, as the names might suggest. Rather the action of all these mutations is to reduce the yellow pigmentation, either entirely or to some degree, with respect to the wild-type Light Green. Had these mutations been named 'Yellow-less' rather than 'Blue' or 'Yellowface' their action might have been more easily understood from the outset. But the traditional names are engrained and are retained here.

The prevailing view is that the Yellowface II mutation, together with the Yellowface I and Blue mutations, are members of an allelic series situated at the Blue locus. Although some breeders still dissent from this view it is the one followed here.

On its own, the Yellowface II is a simple autosomal recessive with respect to the wild-type. Visibly, its action appears to be similar to that of the Blue mutation. The heterozygote or Light Green/yellowface II with one Yellowface II allele and one wild-type allele is visibly indistinguishable from a Light Green, and the homozygote with two Yellowface II alleles is like a Skyblue with a variable green suffusion on the breast.

The SF Yellowface II Skyblue variety, described in Appearance above, is a composite of the Blue and Yellowface II mutations, having one allele of each.

The loci of the Dark budgerigar mutation and the Blue allelic series are situated on the same autosome, so the Dark mutation is linked to the Blue allelic series (see genetic linkage). The cross-over value (COV) or recombination frequency between the Dark and Blue loci is commonly stated to be about 14%, [6] but some experiments have found much smaller values (see Genetics in the Dark budgerigar mutation).

Related Research Articles

Budgerigar colour genetics

The science of budgerigar color genetics deals with the heredity of mutations which cause color variation in the feathers of the species known scientifically as Melopsittacus undulatus. Birds of this species are commonly known by the terms 'budgerigar', or informally just 'budgie'.

The Recessive Pied budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Danish Pied variety, aka Harlequin. It is believed by Inte Onsman of MUTAVI to be the same mutation as the Anti-dimorphic Pied found in some parrots. The Dark-eyed Clear variety results when the Recessive Pied and Clearflight Pied characters are combined.

The Blue budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Skyblue, Cobalt, Mauve and Violet.

The Dark budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Dark Green and Olive in the green series and Cobalt, Mauve and Violet in the blue series.

The Yellowface I budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars.

The Dominant Grey budgerigar mutation, often called the Australian Grey or simply Grey, is one of approximately 30 mutations affecting the colour of budgerigars. It is the basis of the Grey-Green and Grey standard varieties.

The violet budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is one of the constituent mutations of the violet variety.

The Dilute budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is one of the constituent mutations of several recognised varieties: the Light, Dark, Olive, Grey and Suffused Yellows and the Grey and Suffused Whites.

The Clearwing budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Clearwing variety, often known as Yellowwings in the green series and Whitewings in the blue series. When combined with the Greywing mutation the variety is known as the Full-bodied Greywing. When combined with the Yellowface II and Opaline mutations the Rainbow variety is produced.

The Greywing budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Greywing variety. When combined with the Clearwing mutation the variety is known as a Full-bodied Greywing.

The Opaline budgerigar mutation is one of approximately 30 mutations affecting the colour or appearance of budgerigars. It is the underlying mutation of the Opaline variety. When combined with the Yellowface II and Clearwing mutations the Rainbow variety is produced.

The Cinnamon budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Cinnamon variety and, with Ino, a constituent mutation of the Lacewing variety.

The Ino budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Albino and Lutino varieties and, with Cinnamon, a constituent mutation of the Lacewing variety.

Slate budgerigar mutation

The Slate budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Slate variety.

The Dominant Clearbody budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Easley Clearbody variety.

The German Fallow budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. At least three types of Fallow, the German, English, and Scottish, all named after their country of origin, have been established, although none of these types is common. They are superficially similar, but adult birds may be distinguished by examining the eye. All have red eyes, but the German Fallow shows the usual white iris ring, the eye of the English Fallow is a solid red with a barely discernible iris and the iris of the Scottish Fallow is pink.

The English Grey budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It appeared briefly in the 1930s but was lost shortly after and until recently was believed to be no longer extant. However, the appearance of the anthracite budgerigar mutation in 1998 with a seemingly identical appearance and identical genetic behaviour, insofar as can now be determined, suggests the mutation may have been regained.

The Anthracite budgerigar mutation is an extremely rare mutation that occurs in the budgerigar. The mutation, similar to the Violet budgerigar mutation, causes a difference in the coloring of budgerigars. Anthracites have black or very dark gray feathers, possibly with some white depending on the budgerigar in particular. The mutation is believed to have started in Germany, and tends to be local to that area. Currently, most owners wishing to obtain an Anthracite need to import these budgerigars from Germany.

The Clearflight Pied budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Continental Clearflight and Dutch Pied varieties. The Dark-eyed Clear variety results when the Recessive Pied and Clearflight Pied characters are combined.

The Australian Pied budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Banded Pied variety.

References

  1. ↑ Rogers (1973) p46
  2. ↑ Bland, W P (Mar 1962), "A History of Budgerigars", The Budgerigar Bulletin: 25–30
  3. ↑ "Another new variety, 'Golden Cobalts'", The Budgerigar Bulletin (39): 74, September 1936
  4. ↑ Hesford, Clive, The Parblue Puzzle, archived from the original on 14 June 2006
  5. ↑ Bergman, P, Gene function in Yellowface Budgerigars, archived from the original on March 25, 2002
  6. ↑ Taylor and Warner (1986), p 31
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