Moles are not real common in our neck of the woods. Voles are but they are smallish, like big mice. You could have woodchucks but they are big and you would notice them. Stick a hose down a hole and see what happens. You may flood them out and then you can kill em. Are you vegetables begin sampled, a bite or two on each one? Woodchucks. You finding tunnels along the surface of the lawn or just below surface about 1 inch dia. ? if so probably voles and cats are great at that. My cats get 1 or 2 a day. Has been a lot of them this year. Voles eat worms and grubs and my specialty Hosta's in the winter. Good luck.
This may help a little
http://icwdm.org/handbook/mammals/Moles.asp
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