This little guy is what’s known as a piebald squirrel — the term piebald applies to any animal displaying depigmented white fur.
The condition is genetically tied in to the development of the animal’s nervous system. According to some sources, it’s most common in horses but does affect other species.
That is one tasty tidbit of random science there. Visit the links for a picture of the cutest skunk-colored squirrel you’ve ever seen, etc.