Back in Michigan we had jillions of chipmunks, and a distinctly different and less ubiquitous thing known as a ground squirrel, darker with lateral stripes, as distinguished from your annoying little red, the black, and the highly edible fox and the grey squirrel (who was a form of fox, I think).
The California Ground Squirrel or Spermophilis beecheyi is a distinctly different species from all of the eastern squirrels. They aren't that big, but bigger than chipmunks, also nastier, smarter, and one of the best-adapted mammals to the central valley and lower foothills. They are probably closer to prairie dogs, really numerous once established, and live in elaborate burrow systems. Hence the problem, and of course the opportunity.
There are a few of the orange-brown traditional fox squirrels in town, but they are practically pets... wards of the state, if you will. In the Sierras you got yer tufted tree squirrels, but it would take two of 'em to make a decent Michigan fox squirrel.
The CGS and his relative up north, the Belding, are among the few things that even California wants a lot fewer of. While of course they admonish about shooting, they don't rule it out, either. They enthusiastically support gassing, baiting, poisoning with a form of blood agent, and other methods that do make sense in an area where ag is your livelihood, but seem a mite harsh to townsfolk. Still, when the People's Republic of CA puts out the equivalent of a year-round hit on ya, yer just not very cuddly.