They are actually colors... Partridge is a pattern gene. Blue partridge dilutes the areas of black down to different shades of blue. Red partridge are common, but not what the show standard call for on males at all. It takes a double mating breeding system for both the males and females to get the correct colors in the standard. Males are supposed to have that black breast and to achieve that you need to use those darker females that don't fit the standard for their color. The females are supposed to be this nice chesnut/reddish color with penciling. Those dark males are no good for that and you need to keep some of those lighter red partridge to achieve the correct female coloration. So a lot of your breeder birds are not your show birds....
regular partridge:
Red partridge:
Not the best poses, but partridge female coloration
Another coloration that is kind of similar is those blacks with lots of gold leakage. They don't have the pattern gene, thus not partridge (still kind of look like them though). They are blacks that lack the proper melanization to make them black.
black with gold leakage:
Now these 2 are NOT my birds (I don't raise blue part's since they aren't showable other than AOV), but they give good examples of what the blue gene does to dilute the black in the pattern.
