Are the Victor Rat Traps, (I have the ones with the yellow plastic pans), adequate for ground squirrels, (in my case, the California ground squirrels).?
I know you need to drill a hole and tie them off to prevent them from getting hauled off after a catch, and the plastic pan is a bit slippery for staying set. I have used the mouse version and took a fine file to rough up the copper wire dog to help with keeping the pan set but until now have had no use for the rat-size trap.

If they're the size of a red squirrel, yes. If the size of a gray, no.