I have a pest terrorizing my ornamental garden bed. . . I have some first year lorapetalum shrubs I'm trying to nurture to maturity, but something keeps burrowing around them. Also in that bed, I planted about 100 bulbs last fall, including tulips, so I originally thought it was squirrels trying to dig up the tulip bulbs. But the holes I'm finding are pretty deep and look more like tunnels. Is it moles? Snakes? How do you tell? (Other than launching a full on stakeout operation. . .)