Chipmunks are small rodents drawn to the sheltered environment beneath porches, decks, and concrete slabs for nesting and storing food. These areas offer protection from predators, making them ideal locations for their burrow systems. While they appear harmless, their persistent tunneling can compromise the structural stability of surrounding hardscaping. This article provides steps for identifying an infestation, implementing removal strategies, and establishing permanent exclusion barriers.
Identifying Signs of Infestation and Damage
Confirming a chipmunk presence begins with locating their characteristic entry points. Chipmunk burrows are distinctive: the entrance holes are small (one to three inches in diameter) and appear very neat. Unlike other burrowing pests, chipmunks carry the excavated soil away in their cheek pouches, meaning there is usually no visible dirt mound at the entrance.
These openings are often hidden near the foundation, under dense vegetation, or next to steps and retaining walls. Audible signs, such as a sharp chirping or chattering sound during the daytime, can indicate their activity nearby. Homeowners might also hear scratching or rustling coming from beneath the porch floorboards.
The most significant risk is the gradual undermining of supporting structures. Their burrow networks can extend over twenty feet long and three feet deep, displacing substantial amounts of soil from beneath concrete slabs, patios, or foundation footings. This soil displacement can lead to settling and cracking of the concrete, and can create pathways that funnel rainwater toward the foundation walls, increasing the risk of water intrusion.
Immediate Removal Strategies
Active removal is necessary once an infestation is confirmed, with trapping being the most consistently effective method. Small, single-door live-capture traps (ten to twenty inches long) are highly successful. These traps should be baited with peanut butter smeared behind the trigger plate to encourage the animal to fully enter the cage.
Place the live traps directly adjacent to active burrow entrances or along known travel routes to maximize capture chances. Wear gloves when handling and setting the traps to prevent transferring human scent, which can deter the cautious rodents. Once an animal is caught, check local wildlife regulations immediately, as rules for relocating captured animals vary significantly.
A one-way exclusion device or funnel can be temporarily installed over the most-used burrow entrance. This mechanism allows chipmunks to exit but prevents them from re-entering the structure. Leave the device in place for several days to ensure all animals have departed before sealing the area. Lethal methods, such as rat-sized snap traps, can also be used, but they must be placed in covered locations to avoid accidentally catching non-target wildlife or pets.
Repellents and deterrents are generally supplementary tools. High-frequency sonic devices have shown mixed effectiveness, as the sound waves do not penetrate the soil deeply enough to cause significant disturbance. Similarly, strong scents like predator urine or mothballs are not reliable for forcing an established population to vacate.
Long-Term Exclusion and Property Modification
After active removal, the focus must shift to permanent exclusion to prevent chipmunks from returning. The most durable and effective barrier is an L-shaped footer constructed from heavy-gauge, quarter-inch mesh hardware cloth. This material must be physically attached to the bottom edge of the porch or foundation structure.
Dig a trench around the entire perimeter of the porch, extending at least twelve to eighteen inches deep. The attached hardware cloth is then bent outward at a ninety-degree angle, creating a horizontal “L” section that extends eighteen to twenty-four inches away from the structure. This underground shelf prevents chipmunks from tunneling directly under the barrier, forcing them to encounter the mesh as they attempt to dig.
Once the barrier is installed, backfill the trench with soil, completely burying the hardware cloth footer. Before finalizing any permanent sealing, wait five to seven days after the last sighting to confirm the area is clear. Any remaining holes or gaps above ground should be sealed with concrete or the quarter-inch mesh to eliminate all access points.
Modifying the property makes it less appealing to chipmunks. Start by removing common food sources, such as fallen birdseed, nuts, or fruit from trees. Bird feeders should be moved far away from the porch or replaced with types that do not spill seed onto the ground. Additionally, trimming back dense shrubs, ground cover, or wood piles immediately adjacent to the porch eliminates the protective cover chipmunks rely on.