Chimney swifts in your chimney: what the law says

Noise in the flue in summer is often a bird, and that changes who is allowed to do what. This guide covers the rule and a safe order of operations. For a squirrel, raccoon or a bird that is not a swift, see the animal and bird removal service page.

What the law says

Chimney swifts nest and roost in masonry chimneys. The Fish and Wildlife Service says they are protected by the federal Migratory Bird Treaty Act.

The Service adds that harassing, injuring or killing swifts, their eggs and nests is illegal. Illinois Extension (September 17, 2026) says most native birds and their active nests are protected under the Migratory Bird Treaty Act and the Illinois Wildlife Code.

The calendar in Illinois

The Fish and Wildlife Service says swifts arrive in the U.S. in March or April and depart in August or September. Illinois DNR gives no spring arrival date, so for planning treat spring through September as swift season in Winnebago County.

If you hear birds in the chimney

1. Do not light a fire, use smoke or poke at the nest. Any of those can harm the birds or the young.
2. Do not hire anyone to remove the nest or the birds during the season. Someone who offers to is breaking the rule.
3. Keep the fireplace unused until the birds leave.
4. Wait until September or October, when the birds have migrated, then have the chimney inspected and swept.
5. Ask for a cap to be fitted while the chimney is empty, so the birds cannot return next year.

If you are not sure the sound is a swift, say so when you call. Whoever visits should identify the animal first, because the rules for other animals differ.

When the chimney also vents an appliance

This is the hard case, and it is common in Rockford. 83.5% of county homes heat with gas, and many older houses vent a furnace or a water heater through the masonry chimney. A water heater runs all year, so a nest in that flue can block exhaust while the birds are present. Nicor Gas says blocked vents can let carbon monoxide into the home, and that a yellow or orange flame can mean poor combustion or venting. If an alarm sounds, leave the house and call for help. If the appliance is struggling but there is no alarm, ask a sweep or wildlife professional how the law applies to the nest. Do not remove it yourself.

The carbon monoxide alarm guide explains where the alarms go.

After the birds leave

A cap with mesh keeps swifts, other birds and animals out, and it keeps rain out too. The cap guide explains what a cap does. HomeGuide prices a cap at $200 to $850 (HomeGuide, chimney cap cost, national, updated February 9, 2026), and Angi at $190 to $650 (Angi, chimney cap cost, national, updated April 6, 2026). A cap and a sweep together are the usual fall visit.

Other animals cost more

A raccoon, squirrel or non-swift bird in the chimney is a different job. HomeGuide prices animal removal from a chimney, including trapping, cleaning, an exclusion door and sealing, at $600 to $1,500 (HomeGuide, animal and wildlife removal cost, national, updated February 13, 2026). Angi prices a sweep freeing a trapped animal at $200 to $600 (Angi, chimney sweep cost, national, updated July 10, 2026). These are national figures; no cost guide has a Rockford price. Swifts are not trapped or removed, so those prices do not apply to them. All ranges are on the chimney cost page.