Corrections: arctic foxes are born in brown or bluish black summer pelts and arctic wolves are born gray.
These are of the Cape species or subspecies (depending upon how you accept the most recent genetic studies on them), and yellow ones have also been spotted in the Kalahari.
Leucistic Canis mesomelas? Wow! Leucistic giraffes in Kenya and leucistic leopards. What is going on?
Habitat fragmentation is causing a lot of inbreeding in the latter two. I don’t know what is going with the black-backs, but in the Cape species/subspecies, there is actually a lot of color variance.