Moles are small mammals that live almost entirely underground. They are the architects behind the conspicuous piles of dirt, known as molehills, that appear in a yard. These soil mounds are a necessary byproduct of their constant excavation and the creation of complex tunnel networks beneath the surface.
The Mechanics of Mole Tunneling
The mole’s body is uniquely adapted for its life as an underground excavator. They possess short, powerful forelimbs equipped with large, paddle-shaped paws that function like shovels for efficient digging. These specialized front feet have long, strong claws and are rotated outward, allowing the animal to move earth rapidly through a swimming-like breaststroke motion.
A mole creates two main types of tunnels. Subsurface runs are shallow feeding tunnels, often just below the grass roots, visible as raised ridges across the lawn. The creation of these tunnels does not typically produce the large, conical molehills.
The prominent dirt mounds are formed when the mole digs its deep primary tunnels, which serve as permanent pathways and living quarters. When excavating these deeper burrows, the mole pushes the excess soil up a vertical shaft to the surface. This displaced earth accumulates at the exit point, forming the classic molehill shape. Moles can sometimes extend their network by up to 18 feet in a single hour.
How to Identify a True Molehill
The visual characteristics of a molehill are distinct. A true molehill is typically volcano-shaped, circular, or conical, with the loose soil mounded evenly around a central point. The soil itself is usually finely sifted and uniform in texture because the mole pushes it up from below, unlike other burrowing animals that toss chunks of dirt out.
The exit hole is often found at the center of the cone and may be difficult to spot because the mole typically plugs it with loose dirt from the inside. These mounds can range in size, sometimes growing up to two feet in diameter and nine inches high.
This appearance contrasts with the mounds created by other subterranean pests, such as gophers. Gopher mounds are generally crescent or horseshoe-shaped, and the exit hole is typically plugged with soil and offset to one side of the pile. Recognizing the difference in the shape and placement of the dirt pile is an accurate method for identifying the specific animal tunneling beneath the surface.
Why Moles Dig Extensive Tunnel Systems
The digging that produces molehills is driven by the mole’s high metabolism and continuous need for food. Moles are insectivores, primarily consuming soil-dwelling invertebrates, such as earthworms, grubs, and insect larvae. They must consume an enormous amount of food daily, often eating between 60 to 100 percent of their own body weight.
The complex network of tunnels acts as a series of traps that capture prey. As earthworms and insects move through the soil, they fall into the open tunnels, and the mole is alerted by vibrations in the tunnel walls. Moles constantly patrol established tunnels, but they must also continuously excavate new foraging tunnels to locate fresh food sources.
Moles are solitary and highly territorial, requiring a vast, exclusive network to sustain their diet. The extensive tunnel systems also include deeper chambers for nesting, raising young, and storing paralyzed prey. Since they do not hibernate and must eat year-round, continuous creation and maintenance of these networks is necessary for survival.