|Sooty Blue bar racing homer.|
|Genetic symbol||So or so|
|Inheritance||Not yet determined conclusively|
|Mutation type||Colour modifier|
|Commonly found in breeds such as:||Racing homers|
Sooty is an allele at the So locus. This mutation's dominance status compared to wild type has not yet been conclusively proven. It is possible that there may be two forms of this mutation, one dominant and the other recessive.
Sooty pigeons appear similar to wild type in the nest, but during their first moult they grow more dark feathers on the wing shield, giving a "sooty" effect. Racing pigeon breeders often call the sooty phenotype "pencil", however it is unrelated to the mutant gene called pencil.