Reader Ed Kroc sent some photos showing color variants of the eastern gray squirrel (Sciurus carolinensis). Sadly, I lost his email, but the photos came with descriptions. A species showing variation like this, if it’s sufficiently common and pretty discrete, is called polymorphic (Greek for “many forms”). Humans, for instance, are polymorphic for hair and eye color.
Black Gray Squirrel, British Columbia [blackness is the result of a dominant allele that can produce even blacker squirrels if they get two copies; see here]:
Gray gray squirrel, British Columbia:
Orange gray squirrel, Illinois:
Toasty gray squirrel #1, British Columbia [JAC: this individual may have one copy of the black gene as opposed to the first squirrel above]:
Toasty gray squirrel #2, British Columbia: