Birds in Your Chimney

Hearing birds inside your chimney is alarming, but the first thing you need to know is which species you are dealing with. That single detail determines everything: whether the birds can be removed now, whether you have to wait, and what the law says about your options. The two most common scenarios in Houston-area homes are chimney swifts and European starlings. House sparrows also nest in chimneys occasionally, though less often than in vents and soffits. Each species has a completely different legal status, and getting this wrong can result in federal fines.

Chimney Swifts – Protected, Cannot Be Removed

Chimney swifts (Chaetura pelagica) are native migratory birds protected under the Migratory Bird Treaty Act. Texas Parks and Wildlife states clearly that it is illegal to remove or disturb chimney swifts, their nests, eggs, or young during the breeding season. Violations can result in fines up to $15,000 and up to six months in jail.

Chimney swifts arrive in the Houston area from their South American wintering grounds in the spring, typically March or April. They nest and raise young through the summer and depart by October. During that window, if chimney swifts have established a nest in your chimney, the nest must stay until the birds leave on their own. The U.S. Fish and Wildlife Service recommends cleaning chimneys and installing caps only during the months when swifts are not present, which for most of Texas means between October and March.

Chimney swifts cannot perch like other birds. They cling to vertical surfaces with their claws and use their stiff tail feathers for support. They build a shallow half-cup nest by gluing small twigs to the chimney wall with their saliva. If you look up into the chimney with a flashlight, you may see the nest attached to the side wall rather than sitting on a ledge or damper, which is a strong indicator that you are dealing with swifts.

The sounds chimney swifts make are distinctive. The adults produce a rapid chattering, and the nestlings make a loud, buzzing begging call when the parents return with food. Many homeowners describe it as a loud, vibrating hum that resonates through the chimney. The noise can be startling, but it is seasonal and will stop once the young fledge and the family migrates south.

If chimney swifts are in your chimney, the best immediate step is to close the damper to keep birds from falling into the fireplace and to reduce the sound traveling into the living space. Once the birds have left in the fall, the chimney can be cleaned and a chimney cap can be installed to prevent re-entry the following spring.

Starlings and Sparrows – Not Protected, Can Be Removed

European starlings and house sparrows are non-native, invasive species that are not protected under the MBTA. Their nests can be removed from chimneys at any time, regardless of whether eggs or chicks are present. There is no required waiting period.

Starlings are the more common chimney invader of the two. They are cavity nesters that treat an uncapped chimney the same way they treat a tree hollow or a bathroom vent duct: as a sheltered space to build a nest and raise young. Starling nests are bulky piles of grass, leaves, feathers, and miscellaneous debris built on the smoke shelf or damper area inside the chimney. Unlike chimney swifts, starlings do not attach their nests to the vertical chimney wall. Their nests sit on horizontal surfaces inside the flue.

A starling nest in a chimney is a fire hazard. Dry nesting material sitting on or near the damper can ignite when the fireplace is used, and the nest material can partially or fully block the flue, preventing smoke and combustion gases from venting properly. Carbon monoxide buildup from a blocked flue is a serious safety risk.

The droppings from starlings nesting in a chimney also create health risks similar to those from vent-based nests. Dried droppings in the chimney can release contaminated dust into the home through gaps around the damper or through the fireplace opening itself.

How to Tell the Difference

Getting the species identification right is the critical first step. Here are the key differences:

Sound. Chimney swifts produce a rapid, high-pitched chattering and a loud buzzing from nestlings. Starlings produce a wider range of sounds including whistles, clicks, squeals, and mimicry of other birds and mechanical sounds. Sparrows produce a repetitive, monotone “cheep-cheep-cheep.”

Nest location. Chimney swift nests are attached to the vertical chimney wall with saliva. Starling and sparrow nests sit on horizontal surfaces like the damper or smoke shelf.

Time of year. Chimney swifts are only present from roughly March/April through September/October. If you hear birds in your chimney during the winter months, it is not chimney swifts.

Flight pattern. If you can see birds entering and exiting the chimney top, chimney swifts drop straight down into the chimney vertically. Starlings and sparrows approach more horizontally and land on the chimney edge before going in.

If you are unsure, do not attempt to remove the nest yourself. A professional inspection identifies the species before any work begins. The page on how to tell what bird is in your attic covers additional identification methods that apply to chimney situations as well.

How The Critter Team Handles Chimney Birds

For starlings and sparrows, we remove the nest and all debris from the chimney, clean the affected area, and install a chimney cap that prevents re-entry. The cap allows proper draft for the fireplace or furnace flue while keeping birds, bats, and other wildlife out of the chimney opening.

For chimney swifts, we follow the law. If swifts are actively nesting, we leave them alone and schedule the chimney cap installation for the fall after the birds have migrated south. We do not disturb active chimney swift nests under any circumstances.

In both cases, we also inspect the rest of the home’s exterior for other bird entry points. If starlings are in your chimney, there is a reasonable chance they have also explored your exhaust vents and soffit openings. Our bird exclusion service covers the full structure, not just the chimney.