Amazing chimney swifts do practically everything while airborne

  • The swift's distinctive silhouette has earned it the nickname "flying cigar."

    The swift's distinctive silhouette has earned it the nickname "flying cigar." Daily Herald File Photo

 
By Mark Spreyer
Stillman Nature Center
Updated 8/4/2021 7:34 AM

I'm really going to enjoy writing about chimney swifts. I say this because chimney swifts allow me to share a story that has been one of my all-time favorites to tell, but we'll save that until later.

The name game

 

This species' name fits it perfectly. They are, indeed, high-speed fliers and they can be spotted near chimneys.

Before they roosted in chimneys, swifts would use tall trees such as large, hollow sycamores.

As our country was domesticated by European settlers, these trees were removed. The adaptable swifts switched to congregating in tall smokestacks.

So, if you're clinging to the side of a hollow tree or chimney, do you want to have long legs or big feet? No and no. This brings us to the scientific name of the swift family, Apodidae, which is Latin for "footless."

They have legs and feet, of course, but they are quite small and not good for perching. That's right, swifts can't perch on a twig.

Footloose and grip free

Virtually all birds have four toes on each foot. With most birds, there are three toes in front and one in back. The back one allows a bird to hold on to a perch.

There are some exceptions to this three and one formula. Woodpeckers, for instance, have two toes up and two toes pointing down. This is quite helpful if you are scurrying up and down a tree trunk pecking for bugs.

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Swifts catch their prey in midair with open beaks. All they have to do with their feet is cling to the side of a chimney.

Conveniently, all four of a swift's toes point forward or up, which facilitates clinging to vertical surfaces.

They also have spine-tipped tail feathers that further help the birds prop themselves against the side of a chimney.

Linnaeus goofed

Roughly 2,000 chimney swifts swirl into Abbott Middle School's smokestack in Elgin during Kane County Audubon's evening watch event in September. Chimney swifts make rapid twittering, chattering calls that are easy to recognize.
Roughly 2,000 chimney swifts swirl into Abbott Middle School's smokestack in Elgin during Kane County Audubon's evening watch event in September. Chimney swifts make rapid twittering, chattering calls that are easy to recognize. - Courtesy of Jeff Reiter, 2018

This brings us to their scientific name, Chaetura pelagica. Before proceeding, a brief review of these two-part scientific names.

Known as binomial nomenclature, the system was established by Swedish taxonomist Carl Linnaeus in the 18th century. Linnaeus' system helped standardize names that, at the time, could vary from one area to another. Once a scientific name clears intense and rigorous examination, it is not easily changed. Back to chimney swifts.

Chaetura means "spine-tailed." Fair enough. But pelagica? Doesn't pelagic refer to the ocean? There aren't too many chimneys or large trees on the high seas.

                                                                                                                                                                                                                       
 

Linnaeus named the swift, and he meant the species to be named pelasgia, after a group of Greek nomads. Naming the migratory swifts after nomads certainly beats a marine designation. Linnaeus himself tried to correct the error but was unable to overcome the stringent dictates of a system he helped create.

On the wing

With feet that can't grasp, swifts have to do everything on the wing, and I do mean everything.

All eating is done airborne. If it is too cold for flying bugs, roosting chimney swifts go into a state of torpor until conditions are favorable to take off and find flying insects.

Between migration and constant feeding flights, it is estimated that a swift will fly for hundreds of thousands of miles during its average 4.6-year life span. They are the most aerial of our landlubbing birds. Scientific studies have documented swifts that flew for months at a time.

Swifts even bathe while airborne. They glide down to water, holding their wings steady, in a long shallow angle. They skim the water with their breast and entire undersurface of their bodies. Then, they vigorously shake the water from their feathers, all while in the air.

They can also copulate in the sky. More often, mating occurs at the nest site during nest building.

Home spit home

Besides hollow trees and chimneys, the versatile swifts will also nest in barns, silos, air vents, open wells, abandoned cisterns, garages, boathouses, lighthouses, and outhouses.

So, how do you stick a nest to the side of a chimney or silo? During nesting season, their saliva glands enlarge and produce extra sticky spit. Both parents fly back with twigs in their beaks and glue together a half-moon shaped cup for their four small, pure white eggs.

By the way, if you have ever seen bird's nest soup on a menu, that nest came from a relative of our chimney swift, the Asian swiftlet. They might as well call it bird spit soup.

Interestingly, both sexes will incubate the eggs. In fact, both genders have brood patches, featherless areas on the underside of the bird that help keep the eggs warm. With many bird species, only females have brood patches.

After the eggs hatch, both parents will feed the young. They stay in the nest for roughly 19 days. The young offspring will cling to the walls of the chimney or tree for another 19 days before departing the nest site.

During this time, they will preen and exercise their wings. One swift family, by the way, will eat more than 12,000 flying insects a day.

As you might expect, the juvenile swifts can usually fly well right out of the gate. Soon, they join their numerous comrades zipping across an urban sky.

Community attraction

Many towns welcome the annual return of these hard-flying migrants. In Raleigh, North Carolina, a century-old chimney was preserved as a former Carolina Coach bus depot was renovated into a chic new food-and-beverage destination.

The new Transfer Co. Food Hall owners protected the old chimney after being contacted by a board member of the local Audubon Society.

Later, the owners received an award for their conservation efforts. At the award ceremony, the state's first lady and more than 100 folks enjoyed craft beer and watched the evening chimney swift show.

Bethlehem, Pennsylvania, recently voted the chimney swift as their official city bird. The city council was persuaded to do so after being educated about the birds by enthusiastic fourth-graders from a local elementary school.

One of the amazing facts about chimney swifts that encourage their protectors is that such a small bird, weighing less than an ounce, flies so far every spring and fall. And therein lies my story.

Science and serendipity

Not all scientific discoveries are made using the "scientific method." Many are made just by accident. Examples include saccharin, the microwave oven, and penicillin. I have one more for the list of serendipitous discoveries.

As some of you might know, I'm a bird bander. This means I have state and federal permits that allow me to catch and mark wild birds using small aluminum rings attached to their legs.

Before recent advances in miniature telemetry, banding was the best way to study bird migration. For the longest time, one species' migration pattern eluded ornithologists. As a Nov. 12, 1944, news release from the U.S. Fish and Wildlife Service put it, "The solution of a centuries-old riddle of bird migration -- the location of the winter home of the chimney swift -- was announced today ..."

The news release mentions that 13 bird bands were recovered. The 13 swifts had been banded in Tennessee, Alabama, Georgia, Ontario, and Illinois between 1936 and 1940.

The bands were found in Peru near the headwaters of the Amazon River. Did a biologist or naturalist find the banded swifts? No.

A researcher studying the native inhabitants of the area noticed that one of the people was wearing an unusual metal necklace. As it turns out, chimney swifts had been shot for food and their bands threaded into a necklace.

After purchasing the bird band chain, the anthropologist sent the tags to the U.S. Fish and Wildlife Service. Hence, the news release. Really, I just love that story.

Species in decline

Knowing where chimney swifts spend the winter just makes me appreciate these nonstop bundles of energy all the more. If you are not near a chimney, late summer and early fall is the best time to watch the gathering flocks put on their amazing aerial displays.

I'm sorry to say that, according to the North American Breeding Bird Survey, chimney swifts have been in a long-term, range-wide decline of about 2.5% per year between 1966 and 2015, resulting in a cumulative decline of 72%.

One can only hope that towns with nest-site chimneys will do their part to maintain nest sites and welcome this dwindling species as their neighbors.

• Mark Spreyer is executive director of the Stillman Nature Center in South Barrington. Email him at stillmangho@gmail.com.

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