The Loud Chattering in Your Chimney: All About Chimney Swifts

HWCS Expert Team

Every summer, homeowners call us in a panic: “It sounds like there are a hundred bats screaming in my chimney!” The noise is intense—a rapid, high-pitched chattering that echoes through the fireplace.

The culprit isn’t a bat. It’s a bird: the Chimney Swift.

The Flying Cigar

Chimney Swifts are unique birds. They spend almost their entire lives airborne. Their feet are tiny and adapted only for clinging to vertical rough surfaces (like brick), not for perching on branches. Before human cities, they nested in hollow trees. Now, they nest almost exclusively in masonry chimneys.

Chimney Swifts are protected under the Migratory Bird Treaty Act of 1918.

  • It is ILLEGAL to remove them. Once there is a nest with eggs or young, neither you nor a wildlife company can legally touch them, move them, or harass them.
  • The Fine: Penalties for disturbing protected nests are severe.

Living With Them

If you have Swifts, you have to wait them out.

  1. The Timeline: The babies are usually loud for about 2-3 weeks before they fledge (learn to fly) and leave the chimney.
  2. Noise Dampening: Close the damper and place a piece of foam insulation board over the fireplace opening (temporarily) to muffle the sound.
  3. Don’t Start a Fire: This will kill the birds and is illegal.

Prevention for Next Year

Once the birds migrate south in the fall (usually by late September/October), you can act.

  • Chimney Cap: Installing a professional stainless steel chimney cap is the only way to prevent them from returning next year. Chimney Swifts are site-faithful; if you don’t cap it, they will come back to the same chimney next spring.

While they are noisy guests, Swifts eat one-third of their body weight in flying insects (mosquitoes, termites) every day. Try to enjoy the free pest control while you wait for them to fly the coop!