Dear Bird Folks,
For the past several weeks we have been hearing chirping sounds coming out of our fireplace. After a little investigation we’ve discovered that Chimney Swifts are nesting in our chimney. We are thrilled, but it’s now getting towards the end of summer and we are still hearing chirping. Shouldn’t the babies be leaving soon?
– Tyler, Harwich, MA
Good for you, Tyler,
What a breath of fresh air it is to receive a note from someone who isn’t upset by chirping in their chimney. Usually when people hear sounds coming out of their fireplace they freak out, grab the nearest phone and call every exterminator in the book, plus a few exorcists. I don’t know why people get so worked up over a few chimney chirps. I’d much rather hear birds chirping than listen to a barking dog, a sound that suddenly everyone is okay with. Next to my house there’s a yappy little dog that never shuts up. It seems to be possessed by demons. Hey, maybe I’m the one who should be calling an exorcist. Do they have dog exorcists? I’m going to look into that.
It’s interesting how few folks are familiar with Chimney Swifts. We all know about House Wrens, Barn Swallows, Purple Martins and many of the other birds that take advantage of man-made structures. But few of us know much about Chimney Swifts, a bird that relies on humans for its survival. Before the colonists arrived there were no Chimney Swifts. Back then, these same birds were called “American Swifts” and they nested in caves and in the hollows of large trees. Then came the Europeans. The Europeans cleared the forests and built settlements. This caused most wildlife to head for the hills, but not the swifts. They waited to see how it was going to play out. When they saw all the new homes, with all the new chimneys, they thought, “Sweet! We can finally move out of the creepy caves.” The birds quickly left the caves and tree cavities, moved into the new chimneys, changed their name to “Chimney Swifts” and their population exploded.
The fact that swifts find our chimneys so appealing amazes me. Inside a chimney it’s dark, covered in soot and the view stinks, but the birds love it in there. Each spring thousands of swifts arrive from the tropics, pair up and quickly go about finding a chimney to nest in. (If chimneys aren’t available the birds will also use airshafts and holes in abandoned buildings.) The other thing that impresses me about these birds is how they build their nests. They aren’t built on a convenient ledge or shelf; swifts attach their nests directly to the side of the chimney. The adults pluck small twigs off of tree branches and then “glue” the twigs onto the wall of the chimney, using their super sticky spit as an adhesive. Scientists have yet to discover what makes their saliva so sticky, but it’s one of the many reasons why you shouldn’t kiss a Chimney Swift, not matter how well you know it.
For most migrating birds the nesting process is fairly short. It only takes a few weeks for many of them to build a nest, hatch their eggs and fledge their chicks. This is not the case with swifts. Even though both adults participate in nest construction, the building process is rather slow. Often, the impatient female starts laying her eggs before the nest is finished being built. Eventually, four or five eggs are laid and the bird begins a long period of incubation. It may take up to three weeks before the young swifts finally hatch out. Baby swifts are born completely blind, which is just as well. If the first thing they see upon hatching is the inside of a creosote-filled chimney, they may want to crawl back into their eggs.
Even after the babies have hatched their growth is slow. It may be nearly a month before the young swifts finally take their first flights, but even then they aren’t gone for very long. While most birds never return to the nest once they leave it, young swifts typically go back to their nest each night for an additional week or two. Ultimately, however, summer draws to a close and the birds must move out permanently in order to begin their long migration to the tropics. The majority of our Chimney Swifts spend the winter in Brazil, Chile and Peru, where they work as tour guides at Macho Picchu.
In recent years the Chimney Swift population has been in decline. Caps and changes in chimney designs have reduced available nesting sites. To provide the birds with alternative nesting locations, some people have constructed “swift towers.” Swift towers are helpful, but they are pretty freaky looking. They look like a tall freestanding missile, only without a warhead on the top.
When compared to other birds of their size, Tyler, the Chimney Swift’s breeding process takes quite a bit longer than we might expect. But as I’m sure you’ve discovered by now, the birds eventually pack up and head out. And by the way, I’m totally jealous that you had swifts nesting in your chimney. Unfortunately, I don’t have the kind of chimney that they like to use. Hey, maybe I’ll build one of those swift “missiles” in my yard. If it doesn’t attract any birds, I can always attach a warhead to it and point it at my neighbor’s yappy little dog. There’s no sense in wasting a perfectly good missile.