Wild canaries were green birds whose genes contained a mix of black and brown on a yellow ground. The blackhooded siskin is a naturally red and black bird. In order to produce the red canary, descendants of the wild canary were crossed with the siskin. The male first cross birds were fertile bringing with them the red factor that was then added to the complete line of domesticated canaries by breeders.  However, in the wild siskins had access to food which would bring out this red factor.  Caged birds also need the proper color food to bring out their red factor.  Good color feeding is simply proper feeding for this hybrid bird, the red canary.