Two things;
1) How many ground squirrels does it take to get a pound of meat? I've eaten tree squirrel before and there sure isn't a whole lot of meat on their bones. I'm saying 6 squirrels to one pound? Just guessing.
2) I've shot ground squirrels with pellet guns, .22s, shotguns, .223, .30-06 and 12 gauge shotguns and not ONCE did I touch one. Let alone think about eating it. Randomshot is right dude, shoot them and leave them. WAY TOO MANY yuckies on them things to make getting sick worth it.
Stick with the rattlesnakes. At least that way you KNOW something is wrong right away!