Note white abdominal patch in the normal gray (3rd picture).   Could the so-called blonde or white morph result from a developmental anomaly where the white patch extends, laterally compressing gray hairs to a narrow dorsal band?  The incredible amount of variation within the white morph can be illustrated by the squirrel seen in picture 7.  The cream or tan fur of the body extends approximately one inch up the tail, the remainder of which is white.  A head patch and dorsal strip are present but less distinctive (click on the picture for different views). This type of variation doesn’t exist in albino colonies

These left and right lateral views of the same tan-bodied/white-tailed squirrel reveal white blotches above the shoulder and under the ears.  The head patch typical of the white morph is clearly seen on the left view while the dorsal stripe is visible from behind in the picture below. 

Pictures by Volney Tinsley

Photos by Mildred Cash and are from the 1970s.
The head patch and dorsal stripe, said to be lacking in the original pair,
are clearing evident by this time.