Rat traps work very well. I used some a couple years ago, and mounted them on
a stake so they would sit vertically. the squirrels didn't stand a chance.

I just drilled some holes through the wood base of the traps and bolted them to
some sharpened 1x2" stakes and planted them around, baited. I got a little
concerned, however, when the neighbor's cats started sniffing around them and
discontinued the plan. Iive traps work well too--and you can build them
yourself for squirrels and rabbits. I have some plans that work really well if
you're interested.