The differences in anatomy and color between many species of chipmunks
are subtle, and refined techniques are required to discover them.
When "measuring" chipmunks taxonomically, it is necessary to use a
"chipmunk scale" and not, for example, a "pocket-gopher scale." In
explanation, some species of pocket gophers closely allied to each
other, and even some subspecies of the same species, differ markedly
in color and in size and shape of parts of the skeleton; comparable
differences are not so pronounced among many species of chipmunks.