Dilution is an ancient mutation which is well known throughout the pigeon world.. Its effects are common in many breeds world-wide and add much to the beauty of our birds. Dilution is a sex-linked recessive mutation and what it basically does is to cut the amount of the pigment which is put into a growing feather by about half. Since pigment is what absorbs the light and since there's less of it than is found normally, we see a different color. A dilute blue bar becomes a silver bar (remember, we're using genetic terminology here, not racing homer or roller breeder-language where the term silver usually refers to an ash-red barred bird). A dilute blue check becomes a silver check (sometimes called dun-check by homer breeders). A dilute ash-red bird is an ash-yellow (ash-yellow bar, ash-yellow check, etc.) A dilute recessive red is a recessive yellow; a dilute brown is khaki; a dilute black is dun. Dilution also cuts bronze to sulpher - not yellow. There can actually be a "dilute" white, or more accurately, a white which carries dilution. However, unless we note the down length of the squeaker in the nest --- dilute birds are short-downed and almost naked -- there's no way to visually determine a "dilute" white from a "non-dilute" white -- because in whites, there's no pigment at all in the feather so we can't tell if there's "normal" pigmentation there or "dilute" pigmentation. . We'd have to depend on breeding tests to figure out which was which. The youngsters produced by crossing the white to a non-white would allow us to determine if the white in question was a dilute or not.
In addition to its wild-type allele, dilution also has another, pale, which is found in many fewer breeds than is dilution. Where dilution cuts the pigment production by half, pale seems to cut it by about a quarter. Pale changes recessive red to gold and it's best known in the Gimpel (Archangel) where it changes a dark bronze blackwing to a gold blackwing. Pale is also seen in some of the continental cropper breeds, e.g., Swing (Steiger) and Saxons. Pale also shortens the down of hatchlings, but usually no where near the shortness produced by dilute. In fact, some homo pale young cocks I've bred have looked almost full-downed at hatch.
Because of some breeding results in my loft -( I'd been crossing gold Gimples onto Marchenero Croppers and Racing Homers) I also feel - with only slight evidence - that pale is much more evident in the pigeon world than is commonly believed. Some "flat" blacks I produced which I knew to be pale Spread were identical to birds I'd been told were just poorly colored blacks in many breeds. Similarly, certain lighter blues were almost identical to light blue families I've seen in race birds. There's still lots of room for anyone interested in documenting pale's place in the pigeon world. Because pale isan allele to dilution it may be carried unnoticed to many breeds. A cock bird heterozygous for dilution/pale is often very similar in phenotype to a homozygous dilute. Such a bird may well introduce pale into a stud which has not seen it before. On the other hand, a cock heterozygous for wild-type/pale, may show little if any change from wild-type. Again, pale may well be introduced to a new stud and be carried along for ages before being combined into a homozygous carrier. In order of dominance, from least to greatest , these three alleles rank: dilution - pale - wild-type. Their genetic symbols are d -- dP -- +
Copyright 1997 by Frank Mosca. This work may be downloaded or copied for non-commercial individual use only. All other rights under copyright are retained by the author.