There has been some speculation in recent years over the inheritance of mottling in certain strains of racing homers, and its relation to a certain type of bronze. What I have to offer here is simply my observations, and I emphasize that I have no hard scientific data to back up my conclusions. (To use Willard Hollander’s terminology, it is just a SWAG - “scientific wild-ass guess”.) The following summarizes what I have observed and surmised after working with three strains of racing homers - Coudou, Trenton and Meuleman.

It is very common to see a mottled effect in recessive red racing homers; and in families of homers bred strictly for flying, the mottled recessive red appears to be far more common than is recessive red self. And furthermore, an exaggerated form of the mottling effect seems much more common in hens than in cocks. Many recessive red homer hens leave the nest as solid-colored birds, only to develop a “rosewing” effect, followed by a near “whiteside” effect by the time the first moult is completed. Although some cocks can be found with the whiteside effect, most cocks will show only minor forms of the mottling, such as a few white feathers among the secondaries or on the head and neck, or a single tail feather that is white. In the following paragraphs I will outline my theories on what is happening, and I leave it to others to investigate. (I understand Ken Davis is working on this, even as I type.)

First of all, let’s note that this mottling effect is NOT typical grizzle. Recessive red mottled birds have been mated to wild-type and have produced no grizzles in the F1. However, they will produce blues with heavy bronzing in the pattern area. I have observed this several times in a family of Coudous originating with the late Steve Hoagland of Iowa. Upon first seeing it, I dismissed it as simply an indication that the blues (in this case saturated T-patterns) were carrying recessive red. These bronzed blues occurred in both sexes. When they were crossed back to recessive red/yellow, both mottled and non-mottled, the mottling always showed up in the recessive reds. The mottling even reached the point that I could predict the sex of the offspring by the amount of white appearing as the young birds moulted. These effects continued when the same family of birds were crossed with a recessive yellow Trenton cock who showed no white. And now I see similar results as I work with just a few recessive red Meulemans from different families: heavily mottled hens and cocks that show little or no mottling.

At this point, I believe the mottling is caused by a sex-linked bronze factor that modifies the phenotype of recessive red in the following way:

1) This bronze factor, when on a non-recessive red bird, causes heavy bronzing in the pattern area of the juvenile plumage in both sexes, and is unchanged when homozygous in a cock.

2) In conjunction with recessive red, and WHEN IN THE HETEROZYGOUS OR HEMIZYGOUS STATE, it causes extreme mottling in both sexes.

3) In the homozygous state in cocks the bronze takes control and darkens rather than lightens the feathers, leaving the cocks with only a few white feathers or no white at all.

4) A recessive red hen without the bronze factor shows no mottling.

Could this bronze factor that I postulate be the same as undergrizzle? Perhaps, but I doubt it, because I don’t think this bronze factor is recessive. But perhaps some of the current research might be directed toward finding this out. Is this the same effect as occurs in English SF tumblers? Perhaps. I don’t claim to have the answers, but I do think that anyone who desires to research this effect should at least consider my musings.

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