When my parents went out west last summer to visit the Grand Canyon and Yellowstone, they saw this squirrel during their time at the Grand Canyons. I have been editing their photo collection (all their hundreds of photo files are now on my Mac Mini) for occasional printing. Glancing through it tonight, I saw this picture and I can't determine for certain if this is a Western Gray Squirrel, an Arizona Gray (Wikipedia has no entry on this particular species, but I've seen references elsewhere), or a different subtype.
Anyone have an idea which squirrel species this is for certain? I'm guessing Arizona gray, but it's hard to tell when I look at pictures of both that and the Western Gray.
Regardless, I'm certain it was a moment away from attacking my parents for not feeding it.