What is a Chimney Swift?
Chimney Swifts are dark gray-brown, swallow-like birds with long, slightly curved wings and stubby tails. They fly with stiff, rapid wing beats. Their call while in flight is a series of quick, chittering noises. The swift's nickname is a "flying cigar" because of its short 5.25" body and its 12.5" wingspan. This small bird spends almost its entire life in flight, feeding and drinking on the wing. Swifts help keep insect numbers in check and eat up to half their weight in flying insects each day! Chimney Swifts nest and roost in chimneys, concrete silos and in other enclosed vertical masonry.
Unfortunately, Chimney Swift populations are declining throughout North America. One reason for this decline may be that fewer chimneys remain uncapped and available as habitat. Our chimneys are their homes — they return to the same chimney each year and are dependent on us to provide nesting and roosting space.
WI Humane Society
Congratulations! It's easy to be a swift landlord. Just keep the chimney clean and the fireplace damper closed. You likely will not have a problem with swifts entering the house from the fireplace. Occasionally, hard summer rains may loosen the nest from the masonry chimney, especially if there is a creosote buildup. If the nest falls onto the damper, or if the damper is open, you may find a nest or young chicks in the fireplace.
If this happens, contact a licensed wildlife rehabilitator to decide on the most appropriate action. In Wisconsin, refer to dnr.wi.gov/topic/wildlifehabitat/directory.html to find a local rehabilitator or facility that can help.
You can also contact the Wisconsin Chimney Swift Working Group at (608) 658-4139
How Can I Help Chimney Swifts?
Educate friends and neighbors about Chimney Swifts.
If you have a masonry or clay flue-tile chimney, keep the top open and the damper closed from April through October to provide a nest site for swifts.
Best time to clean your chimney is from November through March before the Chimney Swifts return from South America.
If you are converting a furnace or hot water heater to gas, use an alternative venting system, leaving the existing masonry chimney unlined and uncapped for swifts.
Swifts also nest in barns or masonry structures such as concrete silos. Keep a top entry open for swifts.
Identify and preserve Chimney Swift roosting or nesting chimneys in your community.
Swift on Nest Inside Silo, Photo by Jim Edlhuber
Chimney Swift Structure Use
There are two types of roosts that Chimney Swifts use: nesting roosts and resting roosts.
Jack Bartholmai
Nesting Roosts are used during the breeding season. Only one Chimney Swift pair nests per chimney. When nest building they gather twigs in flight, snapping them off with their feet as they pass. An average nest consists of 265 twigs held together with saliva.
Dick Nickolai
Resting Roosts are used during migration and also by unmated swifts in summer. Swifts gather in groups (sometimes very large groups) in communal roosts in large chimneys, often whirling in a huge circle as they funnel down for the night.
Chimney Swifts historically nested and roosted in hollow trees. As American pioneers moved westward across the continent, they cleared forests and removed the swifts' natural habitat. The birds that Audubon called American Swifts became known as Chimney Swifts as they readily adapted to the masonry chimneys erected by those same pioneers. Over the decades, the range of the swifts expanded with the ever increasing availability of this new, man-made habitat. However, environmental changes, including fewer chimneys, are now challenging this species.
What's That Sound in My Chimney?
Chimney Swifts create a variety of sounds when nesting. There is the "whooshing" sound of their wings as they come and go from the chimney. They utter a gentle "chippering" as they socialize with one another during nest-building and at night. The most audible sounds are those of the young which includes a very loud, high-pitched "yippering" as they beg for food from the parents, and a mechanical, hissing alarm call made when disturbed or frightened.
Once the sound of the young becomes noticeable, they are usually only 10 days or so from leaving the nest. The homeowners' tolerance during this critical period of the swifts' development is very important. Keeping the damper closed and packing the fireplace with insulation can dampen the sound to tolerable levels.
For nesting, Chimney Swifts do not require acres of unspoiled wilderness, expansive wetlands or complicated wildlife management plans. All that is needed is one square foot of unused column such as our chimneys during the summer when not being used…and a little tolerance.
This is an edited excerpt from Rehabilitation and Conservation of Chimney Swifts, Fourth Edition by Paul and Georgean Kyle. Copyright, 2004