The sudden appearance of tunnels and mounds across a lawn signals the presence of a burrowing animal. Identifying the specific culprit requires close observation of the visible damage, as excavation patterns and feeding habits are unique to each species. The characteristics of the mounds, tunnel depth, and nature of plant damage provide physical clues for accurate identification. Understanding these distinctions is the first step in addressing the problem, as different animals require different management approaches.
Identifying Tunnel Systems
Subterranean activity is identified by three categories of evidence: mounds, shallow surface pathways, and plant damage linked to the animal’s diet. Mounds of excavated soil are the most noticeable signs, but their shape and placement are highly specific.
Mole hills appear as conical, volcano-shaped piles of soil, often showing up randomly. These mounds form when the animal pushes dirt vertically from a deep main tunnel, and the central entrance is frequently obscured by loose soil. Gopher mounds, by contrast, are typically fan-shaped or crescent-shaped, with the entrance hole always plugged with soil and positioned off to one side. Voles and shrews rarely create large mounds; instead, they leave visible, shallow runways in the grass that look like trails of clipped or dead vegetation.
Moles: The Insectivore Excavator
Moles are insectivores whose tunneling is driven by the pursuit of earthworms, grubs, and other subterranean insects. Their large, paddle-like forefeet are designed for swimming through the soil, allowing a single mole to excavate an impressive network of tunnels, sometimes over 100 feet per day.
The characteristic volcano-shaped molehill results from the animal pushing soil up from deeper, permanent tunnels, which can be 16 to 18 inches below the surface. Moles also create shallow feeding tunnels just beneath the turf, appearing as raised ridges that feel spongy when stepped on. The damage to the lawn is purely mechanical; moles do not eat plant roots, but their tunneling can inadvertently uproot and dry out the grass.
Voles and Shrews: Surface Runners
Voles and shrews are often grouped because both rely on surface-level movement, though their dietary habits differ greatly. Voles are rodents and primarily herbivores, consuming grass, roots, seeds, and the bark of trees and shrubs. Their feeding causes girdling damage on young trees and the consumption of plant roots and bulbs, leading to significant plant loss.
The most telling sign of voles is their network of narrow, surface runways created through the grass or leaf litter. Shrews are insectivores and possess a high metabolism that requires them to eat frequently. Shrews often reuse the tunnels and runways made by voles and moles, and they do not typically create their own extensive tunnel systems.
Gophers: The Root Eaters
Gophers are strict herbivores that consume plant roots, bulbs, and tubers. They are powerful rodents that use large claws and incisor teeth to dig, creating deep tunnel systems that are much more extensive than those of a mole. Their tunneling often follows the root systems of desirable plants, making them highly destructive to gardens.
The gopher’s mound is a distinct indicator, characterized by its plugged, fan or horseshoe shape, and the soil is generally coarser than a mole’s. These animals are meticulous about sealing their tunnels with soil to protect against predators and maintain a controlled subterranean environment. A clear sign of gopher activity is when an entire plant appears to be pulled suddenly down into the earth, as the animal will sever and consume the roots before pulling the rest of the plant down for consumption.