It's a Ground Squirrel. A reticulated Ground Squirrel. When I lived in Oakland I used to feed a colony of the critters peanuts during my lunch breaks not too far from the Temp agency office. It was kind of interesting to watch them interact withe each other with their "Family" hierarchies, and their bold antics when food was involved. The group I watched even had chirps and squeaks for "Food id here!" and "Here comes a dog!" Unfortunately the little critters are destructive, undermining the dunes and digging up the lawns in the park, and I believe the park department poisoned or trapped the colony because none showed up the last time I was there.

i think the arboretum where these are protects them. they run all over the place there at certain times of year and there are signs about not chasing them away and stuff.

How darling. When I was living on the Colorado river every night I would walk down there and cluck my tounge and this nutria would come to me and I would feed him with scraps. One night he was a no show, and I never saw him again. We have squirrels everywhere here and watching them as my cat watches them is just so much fun. I am very partial to ground squirrels, prairie dogs, rabbits, etc. Great picture.