This Abert's squirrel is unusual in two respects.
First, it is in the bird feeder, making it only the second Abert's to have gone there. I blogged earlier about the trail-blazer squirrel.
There is a black one hanging around with this gray one (courtship?)--and maybe that is the same black squirrel that I previously photographed.
Which brings me to the second oddity: All that I ever see in southern Colorado are black-phase Abert's squirrels, so this one's coloration is unusual for our area. Obviously the genes for the two-tone coat must be present in the black population.