When bats take up residence inside a structure, such as an attic, chimney, or wall void, removal is necessary. Although bats are ecologically valuable for insect control, their presence indoors requires humane exclusion. This process guides bats safely out of the structure without causing them injury or harm. This method ensures the animals can continue their beneficial activities while the home remains free of unwanted tenants.
Understanding Bat Protection Laws
Removing bats from a structure is governed by strict wildlife protection laws because all bat species are protected. These laws prohibit killing, injuring, or disturbing bats, and they also make it illegal to damage or destroy an occupied roost site. Exclusion must be performed legally, often requiring consultation with local wildlife authorities or licensed professionals.
A primary restriction is the “maternity season,” which typically runs from late spring through late summer. During this time, female bats gather to give birth and raise their single, flightless young, known as pups. Any exclusion attempt during this period is strictly prohibited because it would trap the pups inside the structure, leading to their death. Therefore, the safest and only legal time for exclusion is usually in the late autumn or early spring, before the breeding cycle begins or after the young are able to fly.
Locating the Bat Entry Points
Before any exclusion device can be installed, a thorough inspection is necessary to identify all entry and exit points. Bats can enter a building through surprisingly small gaps, often requiring an opening no larger than 1/4 to 1/2 inch wide. These small cracks and crevices can be found along the roofline, eaves, fascia boards, ridge vents, or uncapped chimneys.
One of the most reliable signs of a roost is the presence of guano, or bat droppings, which typically accumulate beneath the entry point. Bat guano can be distinguished from rodent droppings because it crumbles easily into a fine powder when touched. You may also observe dark, oily rub marks around the entrance hole. The most effective diagnostic method involves observing the building exterior at dusk to visually track the bats as they emerge to forage and pinpoint their exact exit locations.
Humane Bat Exclusion Techniques
The entire process of humane bat removal hinges on the use of a one-way exclusion device. This specialized mechanism, which can be a tube, cone, or a flap of netting, allows bats to exit the structure but physically blocks their ability to re-enter. The device must be installed over the primary entry point after all secondary openings have been sealed with caulk, wire mesh, or other suitable materials.
When using netting or plastic sheeting, the material should be secured firmly at the top and sides, leaving the bottom edge unattached and extending approximately 18 to 24 inches below the opening. This creates a temporary chute that the bats drop down through when leaving for the evening. Since bats cannot fly straight up from a flat surface, they are unable to navigate back up the hanging flap and are forced to seek an alternative roost site.
The one-way device must be left in place for a minimum of five to seven nights to ensure that all bats have departed. Monitoring is important to confirm that the weather has been conducive to flight, generally meaning temperatures above 50 degrees Fahrenheit with calm winds. In cases involving large colonies, multiple entry points, or difficult access areas, consulting a licensed bat exclusion professional is often the safest recommendation.
Cleanup and Long-Term Prevention
Once the one-way device has been monitored and all bats are confirmed to have left the structure, the next step is to remove the device and permanently seal the former entry point. The final sealing must use durable materials like galvanized hardware cloth or flashing to prevent future access. A significant part of this final stage is the safe cleanup of accumulated bat guano.
Bat guano poses a health risk because it harbors the spores of the Histoplasma capsulatum fungus, which can cause the respiratory infection Histoplasmosis if inhaled. Disturbing dry, accumulated guano releases these microscopic spores into the air. To mitigate this danger, it is mandatory to wear a HEPA-filtered respirator, gloves, and disposable coveralls.
Before beginning removal, the guano should be lightly misted with water or a disinfectant solution to dampen the material. This prevents the fungal spores from becoming airborne. The soiled material should then be scooped up and placed into sealed, heavy-duty bags for disposal according to local hazardous waste regulations. Replacing any insulation that has been contaminated by guano and urine is often necessary to complete the restoration.