Candidate 1: raccoons (most common)
An uncapped chimney is a perfect raccoon den — dark, sheltered, warm. In late winter and spring, mother raccoons raise kits in Orlando chimneys every year. Signs: heavy thumping and movement sounds, especially at night; chittering or crying if babies are present; a musky odor from the fireplace. The damper is the only thing between them and your living room — check that it's closed.
Candidate 2: chimney swifts (protected)
Those fast, chattering birds circling your chimney at dusk in summer are chimney swifts, and they nest inside chimneys — gluing a small nest to the inner wall. Here's the catch: like bats, they're protected, and an active nest can't be removed or disturbed. If swifts are nesting, the honest answer is to wait until the young fledge (usually by late summer), then cap the chimney so it doesn't happen again.
Candidate 3: bats
Bats roost in chimneys too, especially in the gaps around flashing and in unused flues. You'll hear fluttering and high-pitched chirps at dusk as they exit. Same rules as attic bats apply: exclusion only, never during maternity season, never sealed in.
What NOT to do: light a fire
The instinct is to "smoke them out." Don't. A fire with animals (especially babies) in the chimney is inhumane, it can kill them inside the flue — creating a permanent smell and a blocked chimney — and it risks a chimney fire if there's nesting material built up. It's also useless against swifts, which cling above the smoke.
The actual fix
Identify the tenant, remove or wait out appropriately, then cap the chimney with a proper wildlife-proof cap. A cap is a one-time purchase that permanently ends the chimney as wildlife housing. Read about our chimney animal removal service.