Fragile combinations: The example of Frosty-Rubella Pigeons

Combinations of genetic factors often produce interesting colors. So the combination of Frosty and Rubella. The sex-linked color difference of Frosty in cocks and female is increased. Frosty alone does not change the female color.

Fig. 1: Thuringian Self, blue grounded cock-color with bleached bars and blue bar hen-colour. Source: Pigeon Genetics

Rubella is a sex-linked recessive trait but does not show a great difference in the color at cocks and hens in the bar and check pattern variety.

Fig. 2: Rubella bar and check Racing Homer. Source: Pigeon Genetics

But if Frosty meets a female rubella, then the factor unfolds its effect. The young are not short downed. The hens appear like overthrown with hoar-frost, thus frosty in literal sense. At the light silver cocks the pattern, bar or checks, show through soft reddish.

Fig. 3: Sex-Dimorphism at Frosty-Rubella with darker hens in front and two light silver cocks at the outer right

The result of the combination is a small sex-dimorphic strain, which transmits the pronounced gender differences purely. In mating with other colors, including the wild type, this is quickly lost. Both factors are located on the sex chromosome, but far apart. In backcrossing, therefore, one can not assume that the two factors will reappear together in one offspring.

Fig. 4: Sex-Dimorphism at a couple of Frosty-Rubella

Genetically interesting is not so much the resulting color. It is shown by the example that an invisible factor in the hen's wild-type acts as an 'Enabler' and modifies rubella-colored hens. This gives rise to the assumption that the sexual dimorphism originally present in some Spread rubella was also caused by modifiers. These have probably been lost in crossbreeding with blue and blue checks from other strains. Modifiers of a similar kind may also have played or play a role in recessive opal colored racing homers with the Spread factor. Also for them was written in the past in some strains of sexual dimorphism.


Sell, A., Genetik der Taubenfärbungen, Achim 2015

Sell, A., Pigeon Genetics. Applied Genetics in the Domestic Pigeon, Achim 2012