Good Natured in St. Charles: Catbird song mimicry dazzles lucky listeners

I sure do love to sing.

I sing in the shower. I sing in the car. I sing while I’m vacuuming. Loud and proud and maybe a little off key, I’ve never let obstacles like not knowing the words get in the way of a tuneful good time.

Like my old voice instructor once said, I have the vocal stylings of a catbird.

As members of the Mimidae, or mimic family of birds, Dumetella carolinensis will sing for hours on end, pasting together bits and pieces of local birdsong and other pleasant tones with little regard for how things are “supposed” to sound. The Cheery-up-Cheerio song of the robin might only include half of that signature phrase, but is quickly followed by a snippet of northern cardinal, some song sparrow, house finch and maybe the trill of a toad or the beep-beep of a scooter horn.

Put in writing, it doesn’t sound appealing, but, oh boy, when you hear it in person, those jabbery notes are positively entrancing. More than once, I’ve been late leaving because I was listening to a catbird instead of watching the clock.

But, just as amazing as the length and variety of the songs is the way the catbird is able to sing them.

At the top of their throat, birds have a larynx, just like we do. In humans, the larynx has many functions, including directing air into our lungs and food toward our stomach. But it is best known as the location of our vocal chords – those little bands of muscle responsible for the sounds we make – musical and otherwise.

With birds, however, the songs they warble come not from the larynx but the syrinx. Also known as the lower larynx, this organ sits right where the trachea, or windpipe, divides into two bronchial tubes that deliver air to the lungs.

That information is cool in a gee-whiz sort of way, but things get off-the-charts awesome when we learn that the syrinx has two – count ’em, two – sets of vocal chords, one on each side. In accomplished vocalists like catbirds, these two voice boxes can function independently, so the bird can make two sounds at once.

But wait … there’s more! To sing for an extended period (did I mention some songs can last up to 10 minutes?), catbirds take advantage of their uniquely avian respiratory system. Their lungs are fixed and there’s no diaphragm; instead, nine air sacs function like bellows to move air in and out. This arrangement gives them the ability to continuously take tiny micro breaths, each lasting an imperceptible 1/30th of a second. The air sacs allow efficient breathing during flight, and, when the bird is singing, also provide for continual airflow and create the impression of continuous song.

The physiology is fascinating, but the result is what turns people’s heads.

Every morning, I make sure to have a window open so I can listen to our resident male catbird croon away from either a prominent post (his favorite spot is in a silver maple tree) or a hidden perch within the elderberry thicket that rings the backyard.

Every so often though, his recital is interrupted by the sound that gives the catbird its common name – a nasal “Me-eww!” Thought to indicate a potential threat, it’s a sound I heard frequently this past week as I tried to snap a picture for this week’s column. The interactions would go something like this:

Catbird: Cardinal song snippets, squeaks and babbles, chortling sounds, robin song

Me: Trying hard to be inconspicuous but then tripping over a dog toy

Catbird: Silence

Me: Silence

Catbird: After shrinking behind foliage, “MEWWWW!”

Over and over again, this exchange occurred to the point where I was wondering if we’d ever get anything worth publishing. After each bout, I’d go back to the deck, sit down, and wait for the singing to take up again.

On one occasion, as I waited, I turned to one of my favorite references, “Life Histories of Familiar North American Birds,” by Arthur Cleveland Bent. This series of books, published between 1919 and 1968, contains hundreds of eyewitness accounts of birds and their behaviors. (Many chapters of this outstanding resource can be viewed online at www.birdsbybent.com.)

I was particularly taken by the contribution submitted in 1929 by a Penelope Baldwin, who wrote, “I saw a catbird … in the plum tree just outside my window. There was no sound of his song, but I could see that he was singing. Quietly, I opened the window. In came the smell of plum blossoms, in came humming of a thousand bees, in came the whispered song of the catbird, tranquil and clear, indescribably lovely.”

I hope you can find a catbird concert of your own this summer. Look for stands of thick shrubs – the less manicured, the better – that are bearing or soon will bear fruit. Park yourself a respectful distance away, and start listening for squeaks and chirps that are strung together in long phrases. Once he’s comfortable in your presence, the catbird will treat you to a performance you won’t soon forget.

• Pam Otto is the outreach ambassador for the St. Charles Park District. She can be reached at potto@stcparks.org.