This photo illustrates why cross fox and silver fox are considered “forms” or variations of the species Vulpes Vulpes, or commonly called red fox. In order to be a subspecies of the red fox, these two forms would need to be isolated genetically and to not interbreed with “normal” red fox, though they are certainly capable of doing so. But both silver fox and cross fox variants share the same geographic areas and produce offspring that can show the genetic variant or also produce “normal” red fox kits, as seen here as a kit interacts with it’s father