Breeding Blue's
Blue X Blue = 25%Black, 25%Splash, 50%Blue
Blue X Black = 50%Black & 50%Blue
Blue X Splash = 50%Blue & 50%Splash
Splash X Black = 100%Blue
Splash X Splash = 100%Splash

A discussion on the genetics of the color blue.

Blue is one of the best traits to illustrate basic genetics.

Genes come in pairs. Genes are found on chromosomes. You inherit one whole chromosome of a pair from each parent (one from your mother and one from your father). This happens when gametes are formed (sperm and eggs). If the number of chromosomes were not reduced in the gametes each generation would double the number of chromosomes of the previous one. Reduction cell division insures that the offspring have just as many chromosomes as their parents. This means that if your father has two versions of the same gene (one on each chromsome of the pair) he can only give one of these versions to his offspring at a time. Offspring do not inherit both chromosomes of a pair from the same parent except when screwups happen in the process.

The different versions of the same gene are called alleles. For Andalusian type blue there are two alleles. The blue allele dilutes black color to gray and is designated Bl because it is incompletely dominant over the wild-type bl+ allele that produces a fully colored bird. The Bl allele dilutes black more than red and this is why blue wheaten is such a popular color. The males are gray were they should be black and red where they are usually red.

What the bird looks like is called the phenotype, so blue, black and splash are the different phenotypes of the blue locus or gene.

The different versions of the genes that an animal has is called the genotype. Normal birds are bl+bl+, blue birds are Blbl+ and splash birds are BlBl. Blue is an interesting mutation because you can infer all the genotypes from the phenotypes (what the bird looks like).

When a bird is hybrid for two different alleles (Blbl+) it is called a heterozygote. Hetero just means different so this bird has two different alleles of the same gene. When a bird has two of the same alleles it is called a homozygote. Normal-black (bl+bl+) and splash-white (BlBl) are the two types of homozygotes that you can get.

In blue what you see is what you get, so you can accurately predict the outcomes of the different matings between the different phenotypes.

bl+bl+: normal colored
Blbl+: black is diluted to gray (blue)
BlBl: black is diluted even more to mostly white (splash)

The bl+bl+ and BlBl homozygotes can only produce one type of gamete each (bl+ or Bl, respectively). so if you cross a bl+bl+ (black) to a BlBl (splash) you will get all blues (Blbl+). The splash parent can only donate a Bl allele and the black parent can only donate a bl+ allele.

The Blbl+ heterozygote can produce two types of gametes, a Bl or a bl+ gamete. If you cross two heterozygotes they can generate both gamete types and produce all the different allele combinations in their progeny (BlBl, Blbl+ and bl+bl+ in a 1:2:1 ratio). So if you cross two blue birds together you will get 1/4 splash, 1/2 blues, and 1/4 black.

If you cross a heterozygote (Blbl+) to a black (bl+bl+) you will get Blues to blacks in a 1:1 ratio. All progeny have to inherit the bl+ allele from the black parent and half will inherit the Bl allele from the blue parent and half will inherit the bl+ allele from the blue parent generating two types of progeny (Blbl+ and bl+bl+).

If you cross a Blbl+ to a splash (BlBl) you get blues to splashes in a 1:1 ratio. 1/2 of the progeny will be Blbl+ and the other half will be BlBl.

Since all blues are heterozygotes they cannot breed true, but will produce three different genotypes and phenotypes when crossed together.

Splash crossed to splash will breed true and produce all splash.

Black crossed to black should breed true and produce all blacks, but blue is incompletely dominant and some blue (Blbl+) birds may be so dark that they look black. This may account for some of the breeders claiming that they can sometimes get blues by breeding two blacks together. It should not happen unless you misidentify a blue as a black. Blue should be most identifiable in the rapidly growing flight feathers (they should show gray). Tail sickle feathers aren't too good at identifying blue because in males the sexually dimorphic male feathers (hackle, saddle and tail) are more heavily pigmented in Andalusian blue stocks with the black lacing.

Ron Okimoto

 Hits since January 1, 2001  FastCounter by bCentral