Voles or field mice are most likely using old mole tunnels to feed on plant roots and bulbs. You can capture them when they come above ground at night by baiting an old fashioned mouse trap with peanut butter. Place traps near entry hole covered with a box with a small opening if you have pets. To keep mice from moving in leave any dead moles you trap in the burrow. The slow decay of a mole underground will keep a new colony of voles from taking over the runway. Keep growing, Marianne Binetti