Chipmunks often cause concern due to their persistent burrowing behavior. These small rodents create complex underground tunnel systems for nesting and food storage, typically featuring neat, two-inch-diameter entrance holes. When chipmunks excavate next to human-made structures, they displace the supporting soil beneath concrete slabs, patios, sidewalks, and retaining walls. This removal of substrate can lead to settling, cracking, and structural shifting. Their tunnels also redirect water flow toward foundations, increasing the risk of water intrusion and erosion. The most effective strategy is a non-lethal, layered defense focused on making the environment unattractive and physically inaccessible.
Eliminating Food Sources and Cover
The first step in discouraging chipmunk activity is to remove the primary attractants that draw them into the yard. Chipmunks are omnivores drawn to food sources like fallen fruit, berries, and nuts. It is important to diligently clean up any dropped materials and ensure garbage containers are secured to prevent foraging.
Bird feeders are a common and significant attractant, as chipmunks will quickly collect spilled seed, especially high-calorie sunflower seeds and cracked corn. Feeders should be placed at least 15 to 20 feet away from the house, or temporarily removed, to reduce the concentration of food near vulnerable structures. Pet food should never be left outdoors, as it provides another readily available meal.
Chipmunks rely on dense cover near their tunnel entrances for protection from predators. Eliminating these potential hiding spots is a powerful deterrent. This involves removing woodpiles, rock stacks, and construction debris from areas close to the house or patio. Trimming back dense shrubbery or groundcover that abuts foundations also removes the safe concealment they seek for burrow entry points.
Implementing Structural Exclusion Barriers
Physical exclusion is the most reliable method for permanently preventing chipmunks from digging under vulnerable areas. This strategy involves installing underground barriers around decks, sheds, porches, and concrete edges. The material of choice is galvanized hardware cloth, which is a sturdy wire mesh with openings no larger than 1/4-inch to ensure exclusion of the small rodents.
The mesh must be installed using an L-shaped footer technique to create a barrier that extends both vertically and horizontally. A trench should be dug around the perimeter of the structure, extending downward approximately 6 to 12 inches. The hardware cloth is then placed in this trench, extending vertically down the side of the structure.
At the bottom of the trench, the mesh is bent outward at a 90-degree angle, extending horizontally away from the structure for at least 12 inches. When the trench is backfilled, this horizontal apron prevents chipmunks from digging straight down next to the foundation. This forces them to encounter the buried wire barrier.
All existing gaps larger than a quarter-inch in foundation walls or utility openings must also be sealed with 1/4-inch hardware cloth or concrete.
Utilizing Sensory Repellents and Deterrents
Sensory deterrents can be used as a secondary defense layer or for temporary protection, though they require persistent application. Repellents work by irritating the chipmunk’s sense of smell or taste, or by startling them with a sudden interruption. Commercial repellents often use capsaicin, the compound found in chili peppers, which causes a temporary burning sensation in the nasal passages and paws of mammals.
Field studies suggest that while capsaicin-treated birdseed deters squirrels, it may not be effective against chipmunks. For area application, capsaicin-based sprays or powders must be reapplied frequently. This is especially necessary after rain or irrigation to maintain their effectiveness.
Granular or liquid repellents that utilize the scent of predator urine, such as coyote or fox, can also be applied as a perimeter barrier around targeted areas. Another option is the use of motion-activated sprinklers, which deliver a sudden burst of water when triggered by movement. These devices rely on the element of surprise to scare the chipmunks away, but the small size of the animal can sometimes make the activation mechanism inconsistent.