Answer: Of the two, a chipmunk is more likely to make that size hole. ( A woodchuck can be about the size of a large cat.)
Unless the chipmunks are causing real damage, they may not need to be controlled. Some gardeners find that natural predators along with a residentpet cat serve as sufficient deterrent to chipmunks, while others resort to trapping them. Here are some addional details about controlling nuisance chipmunks if you decide it is necessary. http://muextension.missouri.edu/xplor/miscpubs/mx0131.htm
You might also want to verify that it is legal to harm them in your area.
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