Animals and nests in the chimney

Signs something is living in your chimney

• Sounds. Scratching, thumping or scrambling, often at dawn and dusk. Chirping or a rising chatter that gets louder when a parent bird enters is typical of nestlings.
• Smells. A musky or ammonia odor from droppings, or a sour, rotting smell if an animal has died.
• Debris. Twigs, leaves, nest material or droppings landing on the smoke shelf, damper or firebox floor.
• Activity on the roof. Birds diving into the flue at dusk, or a raccoon climbing a downspout or tree near the chimney.
• Insects. Flies or other insects coming from the fireplace can follow a dead animal.

Any of these is a reason to stop using the fireplace until the chimney has been checked. The Chimney Safety Institute of America (CSIA) notes that even a chimney you do not use should be inspected each year because animals may build nests in the flue.

What not to do

• Do not open the damper to look up the flue. A frightened animal can come down into the room.
• Do not put poison or chemicals in the chimney. An animal that dies inside causes odor and blockage, and chemicals can harm pets and children.
• Do not cap the chimney with an animal inside. Sealing the top traps it. Young raccoons and nestlings may be present even when you only see the adult.
• Do not climb the roof to deal with it. Wild animals can bite and carry disease, and roof work is dangerous.

Which animals use chimneys

The Internet Center for Wildlife Damage Management lists raccoons and several bird species, including chimney swifts, starlings, pigeons, owls and ducks, among the animals that enter chimneys. Squirrels, bats and other small mammals also turn up.

One detail matters a great deal: according to the same source, raccoons, chimney swifts and bats can climb or fly out of a chimney, while most other animals that fall in cannot and become trapped. A bird or squirrel stuck on the smoke shelf will usually not leave on its own.

Chimney swifts: a protected bird

Chimney swifts are small, dark birds that spend most of their lives flying. They cannot perch like most birds, so they cling to vertical surfaces such as the inside of a masonry chimney. They build small, half-saucer nests of twigs glued to the flue wall with saliva.

The US Fish and Wildlife Service explains that chimney swifts are protected under the Migratory Bird Treaty Act, and that harassing, injuring or killing swifts, their eggs or nests is illegal. Swifts arrive in the US in spring, generally in March and April depending on region, and leave for South America in late summer and early fall.

What that means for you:

• If swifts are nesting, the nest has to be left alone until the birds leave for the season.
• Keep the damper closed during nesting season so young birds do not fall into the room.
• The Service suggests scheduling chimney cleaning for the period after swifts have left and before they return.
• The Service encourages homeowners who want to help the species to leave masonry chimneys uncapped and unlined with metal. Many homeowners need a cap or liner for safety and water reasons. If you are planning to cap, the time to do it is after the birds have gone for the year.

State wildlife rules can also apply to other species. For questions about a specific animal, the New Jersey Division of Fish and Wildlife is the state agency to ask.

Raccoons in the chimney

Raccoons are strong climbers and are known to use chimneys as dens, especially females raising young in spring. Signs include heavy thumping, chattering or crying sounds from the kits, and a strong odor.

Because young may be present and raccoons can carry diseases, removal is a job for people with the right training and equipment. Methods that encourage the mother to move her young herself, followed by confirming the chimney is empty before closing it, avoid leaving orphaned animals behind. Chimney 911 handles this removal itself, in line with New Jersey wildlife rules.

Once the animals are out, the chimney usually needs cleaning: raccoon dens leave nesting material and droppings on the smoke shelf, and raccoons can damage dampers and flue tiles.

After the animal is gone

1. Confirm it is emptyMake sure no animals or young remain before anything else is done.
2. Remove nest material and debrisNests, twigs, leaves and droppings block draft and can catch fire.
3. Inspect the flue and damperAnimals can damage dampers and dislodge flue tiles. A camera inspection when the flue allows shows what is happening inside.
4. Close the entryA properly sized cap with a mesh screen keeps animals out of the flue. On a framed chase, gaps around the chase cover may need sealing.
5. Address odorDroppings and decay leave odors that cleaning reduces; see Why does my fireplace smell?

Why a cap is the usual long-term fix

A chimney cap covers the top of the flue with a hood and a screen. It keeps out animals, rain and debris, and the screen helps keep sparks from landing on the roof. The Internet Center for Wildlife Damage Management recommends commercial stainless steel caps over improvised hardware cloth, which rusts and can clog with soot and restrict venting.

Sizing and fit matter. A cap must match the flue, sit securely, and not restrict the appliance it serves. Gas appliances and factory-built chimneys often need caps specified by the appliance or chimney manufacturer. See chimney caps and Crown vs. cap: what's the difference?

How we handle animals in chimneys

Every visit starts with an assessment. We check what kind of animal is involved and whether young may be present, and if chimney swifts are actively nesting, we will recommend waiting until they leave. Where removal is appropriate, we remove the animal or nest ourselves using humane methods and in line with New Jersey wildlife rules, clean the flue, fit a cap to close the opening, inspect it with a camera when the flue allows, and show you findings with photos before any repair is scheduled. See chimney animal removal, or request service.

Questions homeowners ask

Sources

1. US Fish & Wildlife Service: On the Wing with Chimney Swifts
2. Internet Center for Wildlife Damage Management: Chimney Cap
3. CSIA: Frequently Asked Questions
4. US Consumer Product Safety Commission: Carbon Monoxide Information Center

This guide is general information. It can't diagnose a specific chimney; an inspection can.