Some what general Question about Leakage and Heterozygous Bases

[RememberTheWay]

So- in my self taught education of chicken genetics I've had a question about color genetics pop up- I see people say things like that bird has leakage- etc- or about a bird being split.

My question is whether or not a bird that is heterozygous for a base (partridge, extended black, Wheaton, birchen, etc) is what actually causes the "leakage" or if a bird that it homozygous for it's base can still show leakage and these two terms are actually two separate phenomenon? Not sure if that makes sense or not. I know a split bird for say partridge and extended black will be mostly black but will have gold (or silver depending on which partridge it's split to) "leakage" - what I'm wondering though if "leakage" is actually something different then a bird being heterozygous for a base and if it is does anyone know any references where I can read about the genetic differences between the two types?

 

[Amer]

Leakage is just a coloquial term for color leaking through on an otherwise black bird. The genetic causes can differ. In some cases it is a bird with a homozygous e base that "should" be black, but it is lacking some melanizers (or it has a eumelanin extension gene) and this will give it leakage. In other cases being heterozygous for a base will cause the leakage.
Whether a bird "should" be black is kind of nebulous... within breeds many different black birds have different e bases, but they're usually homozygous. Black Wyandottes are e^b/e^b But if the variety is supposed to be solid black, color, meaning the absence of melanizers or the presence of pheomelanin extenders, we still call it leakage. Unless the bird is a different color altogether, of course.
But when crossing breeds, then a split base could be leakage.