Conservation Guardians of Northwest Illinois

More Field Notes Previous Next

Home  •  Field Notes  •  Torpedoes of the Air

Torpedoes of the Air, or "What's That in My Chimney?"

Summer 2007 Newsletter

The house wasn’t even finished yet when they came — the “excitement” was evident in their actions and chittering calls, and they took to their new quarters immediately. The architect hadn’t blinked when I asked for a false chimney to be included in the house plans. It would be on the outside end of the garage. The contractor, on the other hand, thought my request was mighty strange, until he saw for himself that the birds were using the structure.

It was May 2001, and chimney swifts, one of the species of birds I grew up with in Connecticut and have loved all this time, were back from South America to spend the summer gorging on flying insects and raising a family. The chimney swift, Chaetura pelagica, is one of 4 species of swifts in North America (80-90 worldwide), and the only one we have here in the Midwest.

Swifts range from southeast Saskatchewan and the Dakotas, south into Texas and to the East Coast. The black swift, Cypseloides niger, of the far Northwest prefers to nest in crevices in cliffs near waterfalls and is North America’s largest with a wingspan of seven and one-half inches. Vaux’s swifts, Chaetura vauxi, prefer forested areas and nest in hollow trees, occasionally chimneys. The more colorful white-throated swift, Aeronautes saxatalis, inhabits dry mountainous areas in the West and is probably the fastest flying North American bird, clocked at more than 200 mph, easily outmaneuvering the peregrine falcon.

It’s amazing how unaware most people are of these speed specialists. They are incredibly fast and fly very high, so are easy to miss, but what fascinating birds they are!

Swallows and swifts show some similarities, but surprisingly, hummingbirds and swifts share a branch of the family tree. Their scientific name, Apodidae, means “without feet.” Of course swifts have feet, but their legs are so small and weak, they never perch. Instead, they must do everything on the wing, including mating and twig gathering for nests, and use their strong claws to cling to vertical surfaces. Were they to be forced to the ground for some reason, it would be very difficult for them to take off again.

Stiff needle-like feathers at the base of the tail in Vaux’s and chimney swifts aid in bracing to a cliff, masonry, or wooden wall. Most birds have three claws in front and one behind. Swifts have all four forward, the better to cling with. Their wings are especially adapted to high speed: long, pointed and curved backward. The bill is small and the wide mouth scoops up insects easily. An expandable throat pouch can sometimes be seen bulging with food for the nestlings.

Twig or pine needle nests are glued together with saliva from large salivary glands that become even larger during nesting season. The delicacy Bird’s Nest Soup is made with the whole nest made entirely of saliva, from another relative of the swift family, Far East swiftlets. Indonesians use elaborate long ropes and apparatus to climb cliffs to harvest these nests, risking life and limb in the process.

Chimney swifts break off small twigs in flight to build a flimsy half saucer, attached to a chimney wall (or historically, a hollow tree wall) about two feet from the top. The 4-5 white eggs take about three weeks to hatch and young fledge in 28-30 days. Mornings, swifts are catching insects low, but as the day warms, they forage higher and higher in the sky. Evening brings them lower again, and I love sitting on the deck watching them careen over the trees and house. Following them with binoculars is a challenge. In late August, I sit outside at dusk and count how many swifts descend into my (their) false chimney. The count is fourteen to date.

Very large migrating flocks will choose a large chimney, airshaft or unused smokestack to roost in, circling round and round in the same direction, gathering more and more birds. At just the right time before dark, all descend into the opening like a column of smoke going back into the chimney. In 1945, an observer in Pennsylvania reported 10,000 entering a big chimney in September. It took 37 minutes!

By the second week of September, our swifts have started their long migration to eastern Peru, northern Chile and northwest Brazil. The sky around my property seems more empty with their departure. I miss them and anxiously await the return in May of the Torpedoes of the Air, the amazing chimney swifts.

— Grace Storch

Books on Chimney Swifts:

• Kyle, Georgean, Chimney Swifts: America’s Mysterious Birds above the Fireplace (Texas A&M University Press) 2005.
• Kyle, Paul and Georgean, Chimney Swift Towers: A Construction Guide (Texas A&M University Press) 2005.

Related Link:

Chimneyswifts.org
Track chimney swifts’ return in spring, learn about wildlife rehabilitation, view photos, and download the chimney swift newsletter. Building plans for swift structures can be found at that website, too.