Lawn moles build mounds to dispose of dirt excavated from deep tunnels or nests, states Robert A. Pierce, Extension Fish and Wildlife Specialist with the University of Missouri Extension office. These mounds are indicative of a permanent residence or pathway underneath, while ridges indicate a temporary pathway.
Tunnels under mounds are located 8 to 12 inches below the soil surface, according to the University of California Statewide Integrated Pest Management Program. These mounds are often connected by surface ridges covering temporary tunnels. Temporary tunnels are created as the moles dig to capture worms, insects and other invertebrates on which they feed. Movement of the soil along these temporary feeding tunnels often helps to identify the exact location of a mole for trapping and removal.
Moles use nests under mounds to shelter a single litter of young born in the spring, states Robert A. Pierce of the University of Missouri Extension office. These litters contain as many as five young, hairless moles. The young moles develop and leave the nest within four weeks. The matured moles use their paddle-shaped feet and long, sharp toenails to navigate through the dirt and build more nests and tunnels as they burrow and search for food.