Chipmunks are small, striped rodents that often create complex burrow systems in yards, sometimes causing damage to landscaping, patios, or foundations. Their burrow entrances are typically small and inconspicuous, making them difficult to identify and manage. Successfully addressing these holes requires confirming activity, using appropriate materials, and preventing the animal from becoming trapped inside. This process ensures the stability of outdoor spaces while encouraging the chipmunk to relocate naturally.
Identifying Active Chipmunk Burrows
A chipmunk’s burrow entrance is distinct from those of other common yard pests. The holes are usually small, measuring between 1.5 to 3 inches in diameter, and are often found near cover like stone walls, dense vegetation, or under structures. Unlike a mole or groundhog den, a chipmunk burrow entrance will not have a visible mound of excavated dirt surrounding it. This is because the chipmunk carries the loose soil away in its cheek pouches and scatters it to camouflage the entrance.
To confirm if a hole is currently in use, perform a simple “plug test.” Loosely stuff the entrance with a light, easily moved material, such as crumpled paper, grass clippings, or loose soil, in the late afternoon or evening. Since chipmunks are diurnal and most active during the day, check the plug the following morning. If the material has been pushed out or removed, the burrow is active and should not be permanently sealed until the animal has been encouraged to leave.
The Mechanics of Filling a Hole
Once you have confirmed that the burrow is inactive or empty, you can begin filling the hole to prevent future use. Standard topsoil alone is not an effective long-term solution because it is easily re-excavated or washes away with rain. Chipmunks are persistent and can quickly dig through loose fill to re-establish their tunnel system.
For holes in the lawn or garden, a mixture of coarse gravel and soil provides a more resistant fill material. Combining three parts gravel with one part soil creates a substrate that is challenging for the rodent to move, as the irregular, heavy pieces of gravel are difficult to maneuver. Use a trowel to pour the mixture deep into the tunnel, filling the void completely before firmly tamping it down. This compaction step removes air pockets and stabilizes the fill, preventing the material from settling over time.
In areas where a permanent seal is needed, such as next to concrete patios, sidewalks, or building foundations, a quick-setting concrete mix can be used. For this method, fill the hole partially with sand or gravel, leaving the top few inches for the concrete cap. This creates a permanent physical barrier that chipmunks cannot dig through. For extra protection, place a piece of galvanized hardware cloth with a quarter-inch mesh size over the filled hole before covering it with a final layer of topsoil.
The Problem with Instant Sealing
Sealing a chipmunk hole instantly without confirming the animal’s absence is counterproductive and can lead to new problems. A chipmunk trapped inside its burrow will immediately begin digging a new escape tunnel. This new exit is often created close to the original entrance, potentially undermining a different section of your yard or a nearby structure. This action defeats the purpose of the sealing effort and creates more damage.
If the chipmunk is unable to dig a new exit, it may die inside the complex underground system, which can extend up to 30 feet long and three feet deep. The decomposition of the animal can lead to unpleasant odors that attract other pests or insects. A better approach involves encouraging the animal to vacate before filling the hole. This can be done by installing a one-way exclusion funnel for a few days to ensure the animal can leave but not re-enter.
Discouraging Future Digging
Long-term success depends on making your yard less attractive to the chipmunk population. A primary preventative measure involves eliminating easy access to food sources. This includes securing bird feeders with trays to catch spilled seed and promptly picking up fallen fruits or nuts. Chipmunks rely on these concentrated food sources for storage in their burrows.
Modifying the habitat by removing potential cover also helps to deter chipmunks. Clear away dense brush piles, stacks of firewood, and excessive ground cover near the foundation of your home or patio. For areas around vulnerable structures, a physical barrier can be installed by burying an L-shaped wire mesh or hardware cloth a few inches underground. This barrier prevents chipmunks from digging new tunnels near the foundation, forcing them to establish their homes elsewhere.