The good thing about ground hogs is that you can hunt them when you see them. You can look out the window a few times a day and if you see some, just go out and shoot them lol. And if you can't get them to stand up, just shoot whatever fur you can see. They are small so even what seems like a minimally damaging shot from a rifle usually does them in. Even if they don't die right away they will die eventually. I know that they dig a lot of holes at my Uncle's farm, that his cows can break a leg in, so even if I can only wing 'em I take the shot. If you can't whistle maybe you could make kissy noises (yeah I know that sounds gay). That will work too.