Name: Sandy B. Ford River Twp, Michigan UP (Zone 4b) (Zone 4b-maybe 5a)
A simple fence will keep them out - it doesn't have to be very high (at least not for the bunnies that we have here), something like 3 feet works fine.
If you are also dealing with deer, though, it needs to be a lot higher.
“Think occasionally of the suffering of which you spare yourself the sight." ~ Albert Schweitzer C/F temp conversion