Looks like a chipmunk ..
Maybe I’m missing something. Do squirrels actually burrow? I thought they made nests in trees?
There are the common grey/red squirrels that are up in trees, and then there are about a dozen very common ground squirrels, especially in the high desert west, where trees are few and far between.
The type of ground squirrel I used to kill in great numbers was the Belding Ground Squirrel:
http://en.wikipedia.org/wiki/Belding%27s_Ground_Squirrel