The appearance of holes in a lawn or garden is a frustrating sign of subterranean activity. These disturbances range from small openings to large mounds of excavated dirt, pointing to different species of wildlife. Correctly identifying the animal responsible is the necessary first step, as the habits and diets of burrowing creatures vary significantly. Understanding the specific nature of the tunnels and holes will guide any effective strategy for protecting your property.
Identifying the Primary Subterranean Pests
The most extensive damage is often caused by animals that establish permanent, complex tunnel systems. Moles are insectivores whose primary diet consists of earthworms and grubs, requiring them to constantly tunnel in search of food. Their presence is indicated by two main structures: raised, linear ridges or surface runways, and volcano-shaped molehills. These mounds are created when they push soil up a vertical shaft from a deeper tunnel and typically have no open entrance hole in the center.
Pocket gophers are major subterranean pests but create different signs of activity. Gopher mounds are characteristically fan-shaped or horseshoe-shaped, formed when the animal pushes soil out of a lateral tunnel. The actual entrance hole for a gopher burrow is almost always plugged with soil, creating a depression on one side of the mound. These herbivores feed primarily on roots and vegetation, with their main tunnels running between 6 and 18 inches below the surface.
Voles, small rodents, create a combination of surface and underground signs. They are known for creating a network of narrow, zig-zagging runways on the surface of the lawn, which look like small trenches worn into the grass. These runways are typically one to two inches wide and connect to multiple small, neat, round burrow entrances. The open holes are usually about the size of a golf ball (1 to 1.5 inches in diameter) and often lack the large piles of excavated soil seen with other burrowers.
Surface Foragers and Temporary Burrowers
Other animals dig holes in the yard not for a permanent home, but to find food or establish a temporary den. Skunks are frequent nocturnal visitors who forage for soil-dwelling insects like grubs and earthworms. They leave behind numerous small, shallow, conical holes, generally one to three inches across, resembling marks left by an aerator. Raccoons also search for the same food sources, but they often use their paws to lift and flip pieces of sod, resulting in larger, more disturbed patches of turf.
Chipmunks are small rodents that create extensive burrow systems with intentionally camouflaged entrances. They dig small, neat holes, often about two inches in diameter, usually found next to structures like foundations, stone walls, or rocks. The chipmunk carries the excavated dirt away in its cheek pouches and scatters it, ensuring there is no visible mound of dirt to reveal the entrance.
Groundhogs, also called woodchucks, create large, obvious permanent burrows, frequently near brush, sheds, or home foundations. A groundhog burrow is typically identified by a single main entrance hole, around 10 to 12 inches in diameter. A substantial crescent-shaped mound of excavated soil is usually present immediately outside this main entrance.
Deciphering the Physical Clues
Interpreting the physical evidence is the most direct way to determine which animal is active on the property. The type of soil disturbance is a primary clue, distinguishing between mounds, open holes, and surface trails. For instance, a volcano-shaped mound of finely sifted soil with no visible hole in the center points directly to a mole. Conversely, a crescent or fan-shaped mound of soil with a plugged hole on one side indicates a pocket gopher.
Open holes are categorized by their size and surrounding environment. Large, open entrances (10 inches or more across) with a substantial dirt apron are characteristic of a groundhog den. Very small holes, around golf-ball size, that are open and connect to visible surface runways, signify the presence of voles. The smallest, neatest holes, often hidden near a structure and lacking any excavated dirt pile, are the hallmark of a chipmunk burrow entrance.
General Principles for Burrow Management
Effective management begins with reducing the environmental factors that attract burrowing animals to a yard. Habitat modification focuses on eliminating food sources and reducing protective cover. This involves controlling lawn grubs and insects that attract foraging animals like skunks and raccoons. Maintaining a dense, healthy lawn also makes it more difficult for animals to dig and access the soil.
Physical barriers and exclusion techniques offer a direct method of preventing access to sensitive areas. For animals that burrow deep or near foundations, installing an L-shaped barrier, such as wire mesh buried at least a foot deep and bent outward, can successfully deter digging. For surface foragers, temporary measures like covering active areas with hardware cloth or chicken wire at night can discourage them from returning to search for food.
Before taking action, confirm the animal’s identity to select the most appropriate method, as techniques effective for moles may not work for voles. It is also important to be aware of local regulations concerning the trapping and removal of wildlife. Focusing on long-term prevention through habitat modification is more sustainable than relying on short-term deterrents or removal efforts, which often only create a vacancy for the next animal.