Animals in the Chimney? What Homeowners Should Know

An uncapped chimney is an attractive location for wildlife — it's sheltered from rain and wind, warm from residual heat, and often above predator reach. The usual occupants:

Birds — some swifts use vertical shafts like chimneys, and other species may nest on the smoke shelf. Some are migratory, others are year-round residents.

Squirrels — highly motivated climbers that easily reach chimney tops. They bring nesting material (leaves, twigs, insulation they've pulled from somewhere) that can accumulate into a significant obstruction.

Raccoons — particularly female raccoons looking for a denning spot in late winter and spring. Raccoons are larger, produce more noise, and can cause more disruption when they're inside a chimney.

Bats — less common in chimney flues specifically, but they do enter through gaps in the chase cover or cap. Wildlife rules around bats vary by species.

Nesting birds deserve special mention because they come with legal implications most homeowners aren't aware of.

Many birds, swifts among them, are migratory and protected under the federal Migratory Bird Treaty Act. That protection can extend to active nests, eggs and young — and from the firebox you cannot tell whether the birds above you are a covered species.

The practical consequence: if birds have an active nest in the flue, treat it as potentially protected. Check what applies before anyone disturbs it, and expect that removal — and capping the chimney, which would shut the adults out — may have to wait until the young have left.

The way to avoid the situation is to screen or cap the flue while it is empty, before birds settle in.

The impulse to 'smoke out' an animal by lighting a fire is understandable and very wrong. For most animals, it doesn't cause them to leave — it causes them to panic and push deeper into the flue, potentially through the damper and into the firebox. Nesting material can ignite. Smoke may enter the living space if the flue is partially obstructed by the animal or nest. And if the animal is already deceased, a fire doesn't address the actual problem.

Don't use the fireplace until you know what's in the chimney and whether the flue is clear. That's the only safe approach.

A living animal in the chimney produces some odor — mostly from the nesting material and the animal itself. A dead animal produces a far stronger, more persistent odor that can spread into the living space.

If you suddenly notice a strong, organic smell coming from the fireplace — particularly if you haven't heard any sounds recently — a deceased animal or decomposing nest material is likely. The source has to be removed and the flue cleaned; odor-masking products don't address it.

The solution to animals in the chimney is a securely fastened chimney cap or screen with intact mesh, sized to keep birds and small animals out while letting combustion gases leave freely.

Have the cap looked at during the annual inspection. The mesh is usually the first part to fail — it corrodes, gets bent in wind, or gets pried by persistent raccoons. An intact, well-fastened cap is the most effective single defense against wildlife getting in.

If you hear or smell evidence of an animal in the chimney, keep the damper closed, don't use the fireplace, and get the flue checked. The first questions are what the animal is, whether it is alive, and whether young are present — the answers decide whether a chimney visit, a wildlife control operator or local animal services is the right call.

Where birds are nesting, find out what applies before anything is disturbed — the protections around nesting birds are specific.

Getting the animal out is the immediate problem. An uncapped flue is the reason it happened, and it will keep happening until that changes.