Eastern Chipmunk

Description:

This chipmunk has a white tip to its tail, which is not normal for an Eastern Chipmunk. There was at least one other white-tailed one sharing its living space. Aside from that little family, all the other chipmunks I saw at the duck pond had normal dark tails. Is this a subspecies, a color phase, or a morph specific to this little family?

Habitat:

Rocks and foliage at the edge of VA Tech duck pond.