For a number of years, we'd had resident woodchucks living in a burrow under our shed near our garden. They would eat from the garden, including beans, squash, kale, and chard, and had ample appetites. We managed to keep the burrow closed for a time after harassing them, then kept them from re-digging by fastening some hardware cloth to the edge of the shed going down a foot, then out a foot away from the shed. (Lots of digging needed here.)
A couple of years ago, one or more woodchucks started to create burrows both under another shed and amidst some plant growth on our backyard hill. (We have a double city lot which is about 1/3 acre in size.) We harassed them and closed the holes, and they did not attempt to dig last year.
This year, we have one which seems intent on taking up residence, and has dug twice under a shed which does not have the hardware cloth. We have indicated to this animal that it is not welcome by re-filling its hole, and it has not been under the shed for a couple of days now, as far as I can tell.
Likely will need to go the route of the hardware cloth here, as well, to really keep them out.
Just a quick note to mention what else is going on here, in addition to caring for my Dad, music, and gardening.
Re: Setting out the 'not welcome' mat - for woodchucks
Oh I can definitely see how woodchucks would cause problems in your garden! Would they eat wood too (just looking at the name!) ? I have something eating strawberries and more this year... whether it's slugs (but then I'd see them in the grass and I don't), birds or something else I don't know... I'm very disappointed because the strawberry plants were doing so well. At least no woodchucks!