If you’ve heard a rapid, chattering sound coming from your fireplace this summer, there’s a good chance a chimney swift family has moved in above your damper. Most homeowners’ first instinct is to get the birds out fast.
Here’s the catch: a chimney swift isn’t a pest you can simply remove. These birds are federally protected, and they do a lot of good while they’re here. The good news: their stay is temporary, and a fall sweep and cap solves the problem the right way.
At Sweeps & Ladders, owner Tommy Nelms spent more than 13 years as a firefighter and is an NFI Wood Burning Specialist, and our technicians are CSIA-certified. Here’s what we want every homeowner from Franklin to Murfreesboro to know about swifts in the chimney.
What Is a Chimney Swift?
The chimney swift is a small, sooty gray bird, roughly 5 to 6 inches long and weighing about three-quarters of an ounce, with a cigar-shaped body and long, curved wings. It’s often called a “flying cigar,” and it’s actually more closely related to hummingbirds than to swallows.
Why can’t chimney swifts perch?
Their bodies are built for clinging to walls, not sitting on branches:
- No perching: Unlike most birds, chimney swifts can’t perch on branches, wires, or rooftops.
- Clawed feet: They cling to rough vertical surfaces with tiny feet and long claws suited only for gripping walls.
- Spiny tail: Each tail feather ends in a stiff spine that braces the bird against the wall. That’s where the genus name Chaetura, meaning “spine-tailed,” comes from.
- Life on the wing: Because they can’t perch, swifts fly nearly all day and only come to rest when roosting overnight or tending the nest.
- Rough surfaces only: Before European settlement, swifts used hollow trees and caves. Today they rely mostly on masonry chimneys, where rough brick, stone, mortar, and clay flue tile give them something to grip.
What do chimney swifts eat?
Chimney swifts are some of the best insect hunters in the neighborhood:
- Flying insects only: Swifts feed exclusively on flying insects, which they catch in the air.
- Huge appetites: According to the U.S. Fish & Wildlife Service, a single swift captures more than 1,000 flying insects a day, and up to 12,000 when it’s feeding young. That works out to about a third of its body weight every day.
- Varied menu: Audubon lists beetles, flies, true bugs, moths, and spiders, plus swarms of winged ants when they emerge.
- Wide range: Swifts can fly more than 60 miles per hour and may cover up to 500 miles a day hunting, often foraging high above buildings and treetops.
Are chimney swifts endangered?
Not officially, but they’re in serious trouble:
- Vulnerable worldwide: The IUCN Red List classifies the chimney swift as Vulnerable, one step below Endangered.
- Steep declines: Partners in Flight puts the species on its Yellow Watch List for steep declines and major threats, with an estimated population of about 8.8 million.
- Fewer insects: A shrinking supply of flying insects is considered a significant cause of the decline.
- Fewer homes: Old chimneys are being torn down, and newer chimneys with narrow, covered, or metal-lined flues don’t work as nest sites.
What Does a Chimney Swift Nest Look Like?
A chimney swift nest is small and easy to miss. It’s a half-saucer of loosely woven twigs, about 4 inches wide and 2 to 3 inches from front to back, glued to the inside wall of the chimney with the birds’ own sticky saliva. Both parents build it, snapping small dead twigs off branches with their feet while flying past.
Only one breeding pair nests in a chimney, though other swifts may roost there at night. A typical clutch is three to five white eggs, which both parents incubate for roughly 18 to 21 days.
Are Chimney Swifts Protected by Law?
Yes. Chimney swifts are protected under the Migratory Bird Treaty Act, a federal law. The U.S. Fish & Wildlife Service is clear that harassing, injuring, or killing swifts, or destroying their eggs and nests, is illegal. Removing or disturbing an in-use nest (one with eggs or young) requires a federal permit, and the agency doesn’t issue permits for simple nuisance problems. In practice, that rules out:
- Pulling down a nest that has eggs or young in it
- Smoking the birds out with a fire
- Capping or sealing the chimney while birds are inside
- Sweeping or doing chimney work while the nest is in use
A reputable chimney professional won’t remove an active nest. The right answer is to wait until the birds migrate, then schedule service.
What Should You Do If You Have Chimney Swifts Right Now?
If you suspect swifts have moved in, these steps will get you through the season:
- Keep the damper closed. A closed damper muffles the noise, keeps birds from getting into your living space, and helps keep a nest or young bird from dropping into the firebox. If your damper is missing or broken, wildlife agencies suggest wedging foam rubber (not fiberglass insulation) above the firebox until the birds leave, then removing it.
- Don’t use the fireplace. Don’t light a fire or burn anything in that fireplace while swifts are present.
- Keep things calm. Federal guidance suggests avoiding especially noisy activity in the fireplace room while there’s an active nest.
What do chimney swifts sound like?
Adult swifts make a high, chattering twitter, often heard as they fly overhead. The sound inside your chimney is usually the young. Once the eggs hatch, the nestlings call loudly whenever a parent arrives with food. The loudest stretch usually lasts two to three weeks, until the young leave the chimney.
What if a baby chimney swift falls into the fireplace?
Young swifts outgrow the nest at two to three weeks old and cling to the chimney wall nearby, sometimes before their eyes are even open, so the occasional youngster ends up in the firebox. If that happens, contact a licensed wildlife rehabilitator. They can tell you whether the bird can go back into the chimney or needs care.
When Do Chimney Swifts Leave Tennessee?
The Tennessee Wildlife Resources Agency says swifts are here from late March or early April until mid-October. Here’s how the year typically plays out in Middle Tennessee:
- Late March to April: Swifts return from their wintering grounds, and pairs begin courting within a couple of weeks of arriving.
- May to July: Nesting season. Pairs build nests, lay eggs, and raise their young.
- Summer: Young birds take their first flights about a month after hatching, then join the adults on the wing.
- Late summer into fall: Swifts gather in large evening flocks. At dusk, hundreds or even thousands may circle in a tornado-like swirl and funnel into a large roost chimney for the night.
- By mid-October: The swifts head south to winter in the upper Amazon basin of South America, a round trip of more than 6,000 miles.
- Late fall through early March: Your window to sweep, inspect, repair, and cap the chimney before they return.
How Do You Get Rid of Chimney Swifts Legally?
The legal approach is simple: let them finish the season, then take care of your chimney once they’ve gone.
Why sweep the chimney after swifts leave?
A professional chimney sweeping removes the old nest material along with soot and creosote. The swift nest itself isn’t the big fire risk. Creosote buildup is, and fall is the right time to clear it before you start burning. The Fish & Wildlife Service recommends cleaning chimneys every year, outside of swift season.
Why schedule an inspection in the fall?
Fall is also a smart time for a chimney inspection. Our CSIA-certified technicians can check for cracks, moisture damage, or a damper that doesn’t seal well. If your damper needs attention, we also handle damper replacement.
When should you install a chimney cap?
If you don’t want swifts back next year, installing a chimney cap after they leave and before they return in late March is the practical step. Swift pairs tend to return to the same chimney every year, so timing matters. A chimney cap with mesh sides keeps out swifts and other animals while blocking rain and debris.
A cap is essential if your chimney has a smooth metal flue liner. Swifts can’t grip metal, so a bird that drops into a metal flue can get trapped.
How Can You Help Chimney Swifts?
Some homeowners enjoy hosting swifts. If that’s you, consider one of these options.
Can you leave your chimney open for swifts?
If you have a masonry or clay-tile-lined chimney you never use, and it isn’t connected to a furnace, water heater, or other appliance, you can leave it uncapped for the swifts. Keep the damper closed, schedule sweeping and repairs between mid-October and March, and don’t use that flue while the birds are present. This only works with masonry; metal-lined flues should always be capped.
What is a chimney swift tower?
A chimney swift tower is a freestanding structure built to mimic a chimney or hollow tree. Conservation groups such as Audubon chapters and the Chimney Swift Conservation Association publish building plans for backyards, schools, and parks. Typical designs are 8 to 12 feet tall, with a rough interior surface the birds can grip and an insulated double wall.
Frequently Asked Questions About Chimney Swifts & Your Chimney
Can I hire someone to remove chimney swifts during nesting season?
No. Because chimney swifts are protected by the Migratory Bird Treaty Act, nobody can legally remove the birds, eggs, or an in-use nest without a federal permit, and the U.S. Fish & Wildlife Service doesn’t issue permits for nuisance problems. A responsible chimney sweep will reschedule your cleaning instead. Texas Parks & Wildlife advises sweeps to wait at least six weeks if there are eggs and at least four weeks if there are young, though late fall after the birds migrate is best.
Do chimney swifts carry diseases or damage the chimney?
Wildlife officials say no on both counts. Connecticut’s Department of Energy and Environmental Protection notes that chimney swifts don’t pose a disease risk to people, their presence doesn’t affect how your chimney works, and their nests are not a fire hazard the way creosote is. The main inconveniences are the noise and the leftover nest material, which a fall sweep takes care of.
Do chimney swift bugs get into the house?
Sometimes. Swift nests can host chimney swift bugs, small insects related to bed bugs. They mostly feed on the birds, but after the swifts leave they may wander and bite people. According to university extension entomologists, they aren’t known to spread disease and can’t sustain themselves on human blood. A closed damper and removing the old nest during a fall sweep help.
Can I remove the nest once the birds are gone?
Yes, once it’s truly inactive. Federal guidance says a nest with no eggs or dependent young can be destroyed without a permit, as long as no birds or eggs are harmed and no one keeps the nest. The safest approach is to wait until after mid-October, when the swifts have migrated, and let a professional remove it during your sweep.
Will the same chimney swifts come back next year?
Often, yes. The U.S. Fish & Wildlife Service notes that swift pairs tend to return to the same nesting chimney every year. Most swifts live about four years, and some live as long as 14. If you don’t want them back, have the chimney swept and capped between mid-October and March.
Why are hundreds of swifts flying into one chimney at dusk?
You’re watching a roost. Only one pair nests in a given chimney, but in late summer and during fall migration, swifts gather in big flocks and spend the night together in large chimneys. Cornell Lab of Ornithology reports that as many as 10,000 swifts may funnel into a single roost, and on cold nights the inside of a roost chimney can be up to 70°F warmer than the outside air.
Can I use my fireplace or furnace while swifts are in the chimney?
Not that flue. The Fish & Wildlife Service recommends using your fireplace or furnace only during the part of the year when swifts aren’t present. If your heating appliance vents through the same chimney the swifts are using, talk with a chimney professional about your options after the birds leave.
Schedule Your Fall Sweep and Cap Installation
A chimney swift family is a short-term guest. Once they head south, our CSIA-certified team, led by former firefighter and NFI Wood Burning Specialist Tommy Nelms, can sweep, inspect, and cap your chimney before spring.
We serve Franklin, Brentwood, Spring Hill, Thompson’s Station, Murfreesboro, Nashville, Green Hills, Belle Meade, and Fairview. Request an appointment today to get your fall chimney sweep and cap installation on the calendar.
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