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by Craig Bordeleau Self blue is a dilution of extended black which can be expressed with a gene from a single parent or with two genes (one from each parent). If two genes are present, the resulting color becomes silver rather than blue. The gene itself is incompletely dominant, and in homozygous form, the dilution effect is much more drastic than in heterozygous birds. I will explain how blue dilution works and the differences between its blue and silver variables. Both are quite attractive. This article focuses on domestic ducks, but the genetics are the same as in chicken, and we can apply the information to both species without change.  

The heterozygous blue is seen most famously in Blue Swedish ducks but is also found in Indian Runners, Calls, Cayuga, and East Indies. Of course, it is accompanied by a white bib with the Swedes. The color itself is more of a dark gray than blue, and in the case of the Cayuga and East Indies, the males are a darker shade than the females. There is also darker lacing along the edges of the feathers that add to the aesthetic of the drakes. Females aren’t without their unique patterns, though — they seem to display a much higher degree of black bleed-through. This causes random patches of black to show through the blue dilution. Referred to as “ink spots,” the phenomenon is similar to the spotting seen on Ancona Ducks, although usually to much less of a degree. The blue dilution gene is thought to be unstable in heterozygous form resulting in ink spots. It makes for individuals that can be visually identified without much effort.

Variation within the shade of blue between different birds can be drastic, even between birds that are full siblings. It can sometimes be challenging to identify newly hatched ducklings’ colors correctly. Immediately upon hatching, they can appear to have the yellow down seen in recessive white ducks and then darken over the next few hours, days, or weeks. Most hatchlings also display a bib that disappears as adult feathers come in. Parts of it can last up until the first molting. It’s best to avoid using males who retain some of this white into adulthood as breeders. As with non-diluted extended black birds, white feathers come with age. It’s much more prevalent in females and can occur after the first molt. Usually, it doesn’t start until two or three years old or after incubating a nest for the first time. The bills, legs, and feet are darker in females. Normally slate blue or black. Males tend to have a green-tinted orange rather than blue or black, but high-quality males display blue bills.  

Homozygous silver can be seen in any duck breed that comes in heterozygous blue. The resulting color of two doses of blue dilution is a much lighter gray. In breeds with shade differences between the sexes, the females can appear white. They retain the dark bills and feet. This makes for a beautiful duck with the contrast of black skin with white feathers. The males are lighter in these areas, showing skin, usually orange or pale olive green. The gene is stable in homozygous form, and there is no bleed-through causing ink spots. This color is sometimes called “splash” because the gray can appear splashed with white. Upon hatching and as ducklings, silver ducks have yellow down. As they age, they will darken, and sometimes a bib may be visible after this occurs. There isn’t as much variation in shade as with heterozygous birds. They are still affected by aged white, but it isn’t as radical as a color change.  

Since the blue dilution gene can display in both hetero and homozygous form, there are a few outcomes you can plan for when breeding. Each parent either has zero, one, or two of the genes. They can only pass one to the offspring. If they carry two, they will give one to each of their offspring. There is only a 50% chance of passing it to any given progeny if they carry only one. You can use this knowledge to predict which colors will come from specific color matings.  

• Breeding blue to blue will give you 50% blue, 25% black and 25% silver ducklings.  
• Black to blue will give you 50% blue and 50% black.  
• Blue to silver will generate 50% blue and 50% silver.  
• Silver to silver can only create silver, while silver to black can only create blue offspring.  

Simple calculations can give you whichever colors you’re breeding for, whether it’s a more colorful flock or a more uniform one.  

A couple of things don’t change between these two colors produced by the blue dilution that are different from extended black. Sadly, most black ducks’ captivating green sheen is lost when the gene is present. Chocolate and buff dilutions only occasionally block this feature, while blue dilution does consistently. In males, the head and neck regions are slightly darker than the rest of the body. The difference is subtle but quite visible in good lighting.  

Self blue and silver ducks are spectacularly feathered and certainly my favorites when it comes to different plumages. They stand out alongside other self colored birds. Recent years have seen a rise in their popularity, with diluted Cayuga and East Indies becoming more readily available. I hope that this trend continues and we see these beautiful birds more regularly in the future. 

Originally published in the April/May 2022 issue of Backyard Poultry and regularly vetted for accuracy.