Chimney swifts and bats in a Florida chimney

Before anyone touches the chimney

Whatever is living in the chimney, the first moves are the same, and none of them involve the animals directly.

• Close the damper and keep it closed, so nothing can come down into the room.
• Do not light a fire or use smoke to drive anything out. It can kill the animals, set nest material burning, and push smoke into the house.
• Do not reach into the flue or handle the animals, nests or droppings.
• Keep children and pets back from the fireplace opening, and cover it if the damper does not seal.
• Write down what you hear and when: time of day, which weeks, and whether the sound is high in the chimney or near the damper.

Why nobody should handle them

Droppings carry a disease risk of their own. The CDC traces histoplasmosis to a fungus found in bird and bat droppings, and people become ill after breathing spores released when the material is disturbed. Dry sweeping or vacuuming droppings with a household vacuum is exactly the kind of disturbance to avoid.

Bats add a second concern. The CDC advises avoiding contact with bats, and it recommends seeking medical advice if a bat may have touched someone, or if a bat is found in a room where a person was sleeping or a child was unattended, because bat bites can be very small and hard to see. If that happens, contact your doctor or the county health department before letting the bat go.

Telling swifts from bats

Chimney swifts are small, dark birds that feed on insects in flight and cannot perch on horizontal branches. They cling to vertical surfaces instead, which is why a masonry chimney suits them. The U.S. Fish and Wildlife Service describes a pair building a small half-saucer nest of twigs glued to the inner wall of the chimney with their own saliva. Swifts are active by day, and the chattering of adults and the raspy calls of young being fed are the sounds people notice.

Bats are active at night. A colony leaves the roost at dusk and returns before dawn, and the sounds are squeaks and scratching rather than calls. Droppings that collect below a bat roost are dark and crumbly. When the signs are unclear, the timing of the activity is the best clue, and a view into the flue from the roof settles it.

Are chimney swifts protected? The federal rule

Chimney swifts spend the cold months in South America and migrate north to breed, and they are among the birds the Migratory Bird Treaty Act protects. The U.S. Fish and Wildlife Service is blunt about it: harassing, hurting or killing the birds is illegal, and the same goes for their eggs and nests. It describes swifts arriving in the United States in March or April and leaving in August or September.

In practice, an active swift nest stays where it is until the birds have gone, and the chimney swifts nesting season sets the calendar. Are all birds in a chimney protected? The Act covers native migratory species, not every bird, so identification comes first.

The Service advises cleaning a chimney each year outside the swift nesting and roosting season, roughly from September or October to March or April. It also asks homeowners who can to leave a chimney uncapped, so swifts keep a place to nest. Whether to cap once the birds are gone is the owner's decision, and capping while no swifts are present is lawful.

The Florida rule for bats

In Florida, bats come under the state wildlife commission's rule on taking nuisance wildlife, numbered 68A-9.010 in the Florida Administrative Code. The rule gives no route for killing or trapping bats as nuisance animals. It allows them to be taken only as a side effect of an exclusion device, meaning a one-way device that lets bats leave a roost in a structure but not return, of a registered chemical repellent, or of permanent repairs made after an exclusion has run its course.

The dates matter. Exclusion devices, or anything else placed at a roost that stops bats getting in or out, are prohibited from April 16 through August 14, when females are raising young that cannot yet fly. Exclusion is allowed from August 15 to April 15. When the roost is then to be sealed with permanent repairs, the rule requires the exclusion device to stay in place first for at least four consecutive days and nights with a National Weather Service forecast low above 50 degrees.

Planning the work around the calendar

Put together, the two rules give a simple plan for a chimney with residents. Nothing is sealed, capped or cleaned while protected animals are using it, and the work is booked for the first window the rules allow.

• Swifts nesting between spring and late in the season: damper closed, fireplace covered, wait for migration, then sweep, check and cap if you choose to.
• Bats found between April 16 and August 14: wait for August 15, then exclude, then seal after the device has run its required nights.
• Bats found between August 15 and April 15: exclusion can begin, followed by the permanent closure.
• Once the chimney is empty: a screened cap sized to the flue closes the way in, if you want one.

To cap or not, once they are gone

When the chimney is empty, there is a real choice to make, and both sides have a case. A screened cap keeps most rain and debris out of the flue, stops birds and larger animals, and doubles as a spark screen. Kept in good repair, it breaks the cycle of nests, droppings and noise.

Leaving the flue open keeps a nesting site for chimney swifts, which is what the U.S. Fish and Wildlife Service asks of owners who can manage it. It also means an open top to the weather, a yearly sweep timed around the birds, and a damper that has to seal well. Some owners with more than one flue cap the ones they use and leave an unused one open. The decision is yours, and either one is legal as long as it is made when no protected animals are inside.

What a homeowner can do meanwhile

Most of the waiting is passive. Keep the damper shut, keep the fireplace covered, and leave the animals alone. If the noise is hard to live with, it helps to know the loudest stretch, when nestlings are being fed, lasts only part of the season.

When you bring someone in, ask how they plan to handle the dates above before any work is scheduled. A crew that offers to seal a chimney with swifts or maternity-season bats inside is offering to break the law and to trap animals that can die in the flue. Our chimney animal removal page explains how we plan that work.