you know what works really well against ground hogs aka woodchucks in the NE, are explosives, well technically they work great against anything.......especially those nasty ground hogs. if you wire a small explosive device inside a bagel and leave it by their den, its well worth the wait.
also you can detonate their burrow with a chlorine bomb, made out of rubbing alcohol and bleach or CL- tablets if you have a pool. that stuffs works great. tis all fun and games when you declare chemical warefare on small woodland creatures.