Recessive Red and Yellow
has always been a favorite of mine.
On the surface it appears to be an easy color to work with, however, in reality it can be a challenge. These 2 colors are recessive in nature. Mating a blue check, for example, to a recessive red will produce blue checks (generally). These youngsters will now carry or be split for recessive red. Mating one of these youngsters to a recessive red or a split will produce some recessive red youngsters. The unfortunate reality is that when backcrossing to normal colored birds the red color usually does not come out as a nice clear red. Often the tail and back of these crosses will have a "plum" cast to them. Some genetics people call these unimproved reds. Selecting for color will over time improve the red. The same also pertains to recessive yellow. One can see great red color in some of the show breeds... tumblers, modenas and fantails. Three is a school of thought that says that one should backcross to black rather than blue or ash red to improve the color. I agree with this assessment.
Another factor that appears at times...are white feathers. Occasionally a recessive red or yellow bird when molting will molt in a new feather that is WHITE! This has to do with the feather mechanics. More can be found about this in other genetics resources found elsewhere on this site. These occasional white feathers are not to be associated with "splash" or pied feathering. So if you acquire a red or yellow from a breeder and in years to come white feathering appears, don't feel as though you were mislead! Some strains of recessive reds and yellows molt in more white than others...some not at all.