How to Remove Bats from the Chimney

If you have bats in your chimney, then it is important that you remove them humanely and legally. The bats are in your chimney because it is warm and provides shelter for them and protection from predators. Bats are beneficial to the environment because they eat insects and pests, and many are protected species. Although bats don’t harm your home’s or your chimney's structure, they can cause a number of health problems. In addition, you may want to be able to use your chimney and fire place, and you can't if you have bats. Over time, the guano accumulation will fill your chimney like tobacco fills a cigarette

First of all, DO NOT START A FIRE. Burning bats will flood your living room as they screech down the damper and crawl through gaps down the sides. Special netting must be set on top of the flu, or a special flu-mounted funnel box with cone excluders.

Why Is Timing Important
Depending on the time of year, you could be stuck with your bats for a while. Only colonies of female bats inhabit chimneys, attics, and other places in buildings. The female bats give birth in April or May. Until the end of summer, the babies are flightless and confined to their roost. It is illegal to kill bats, and it is also illegal to perform a bat removal during the months that flightless babies could be present. Even if you wait until the adults fly out and then close up their entrance, the babies will remain. Without their mothers to care for them, the babies will crawl out of the chimney and end up in the living areas of your home. The mothers are also likely to search for new ways to get in and get to their babies. The only legal and permanent way to remove bats from your chimney is to perform bat exclusion. This also can only be done during the months when there are no babies present.



For The Exclusion
Before the exclusion occurs, the entry point or points of the chimney must be found. Bats prefer to exit and enter through horizontal gaps, so it is unlikely that they are going to be coming in and going out through the hole at the top of the chimney. They are most likely entering and exiting through gaps where the chimney meets the roof, or where there is an area of decay in the chimney. Bats only need a gap of 3/8 of an inch to squeeze through, so the entire chimney must be carefully inspected. If you are having trouble locating the entry point, observe your chimney in the evening and wait for the bats to fly out. They may exit from the same point, or there might be several areas. If you can observe them exiting, you can narrow your search.

If you live in an area where the climate becomes colder during the fall and winter months, you can simply wait for the bats to migrate. Listen for the sounds of the bats and observe your chimney at dusk. Once you are sure they are all gone, you can then seal all of the entry points. Sealants can be used on cracks, and you can use netting with a fine mesh to block the top of the chimney and any other area that can’t be completely sealed. The bats will return when the weather gets warm, but if they are unable to get in, then they will move on and find another place to roost.

If waiting is not an option, or your climate is warm enough that the bats don’t migrate then you will need to do a little more work. There are several devices that can be used for live bat exclusion. This is a process in which a device is used at the entry points that will allow the bats to exit, but will not allow them to get back in.

Exclusion devices come in several forms, including pipes, funnels, and netting. The devices are fitted with one-way valves, which allow only for exiting. Before installing the exclusion devices, make sure the damper is completely closed or the bats may exit the chimney and enter the living areas of your home. The exclusion devices are put in place, and used for several days until no more bats are observed. Once you are certain that no bats remain, then the exclusion devices can be removed and the points can be sealed. If bat guano has accumulated in an area that is accessible, you can begin cleaning it up safely. Since it is considered hazardous waste material, safety precautions must be used when cleaning it.

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Bats Can Spread Disease
Bats can carry rabies, which is a virus that causes inflammation of the brain that can be fatal if not treated quickly. The main health risk from bats comes from their guano, or waste. Bat guano carries histoplasma encapsulate, which is a fungus. The spores from the fungus are microscopic, and they are airborne. If you inhale the spores of the fungus, which is easy to do if you have bat guano piling up in your chimney, then you could get the disease histoplasmosis. This disease is a lung infection that can cause significant damage to the lungs and other organs in the body if it is not treated. The first step in removing the bats from your chimney is to determine the species of bat colony in your chimney and formulate a plan for their removal.

Wildlife Education - Information and Advice for the Safe Removal of Bats from Attics