The dense rattle of a flock taking off is one of the most recognizable characteristics of pigeon flight. It’s often used in movies as an essential part of the urban soundscape along with the usual rush of traffic, footsteps, voices, and distant sirens. We tune it out and stop noticing it. And just like any other kind of background noise, when something that is supposed to be noisy suddenly isn’t, the silence is unnerving.

Curiously, the signature sound is produced by a single specific feather on each wing. The inner edge of the outermost flight feather has a section of unusually long, curved barbs that flutter during flight, creating the high-pitched whistling noise. When one of the two is dropped during a molt, the sound dampens—and as flight feathers are often molted in pairs, it can even disappear completely if both are dropped at once.

You may never get a chance to witness a silent pigeon take-off in your lifetime unless you are an incredibly dedicated urban birdwatcher or have the rare horror privilege of housing pigeons at your home. Since they are flock birds and don’t molt synchronously, only a few birds out of a very large flock would have their sound changed at any given moment. Even then, the primary feather molt only happens once a year and the feathers grow back after a few weeks.

Knowing how the sound happens doesn’t give us a lot of insight into why it does. Pigeons are famously common prey for raptors, cats, and so many other animals that at this point you are probably wondering if making a loud noise while moving is really such a clever idea for a bird that is otherwise so remarkably good at surviving. The fluttering also comes with a cost: it slightly reduces how aerodynamic the wing is. With these apparent drawbacks, why hasn’t natural selection done away with it?1

It turns out that pigeons did not, in fact, evolve to be a convenient predator snack. While noise can make a bird easier to locate, most predators that hunt pigeons rely on sight more than hearing. By the time a flock takes off to escape, the noise it makes is largely irrelevant: the predator already knows it’s there.

More importantly, the noise does have an actual use: it can serve as a danger alarm to the rest of the flock. This behavior isn’t well-documented in the ordinary rock doves (ornithologists, take note), but it’s been extensively studied in crested pigeons, the Australian relative of our familiar street bird. The crested pigeon take-off sound varies in tempo depending on the speed of the take-off, and the pigeons differentiate between the routine “righto, mates, better be off” sound and the alarmed take-off aka “OI! EVERYONE LEG IT!”

Since the alarm sound is mechanically tied to the escape itself, it is intrinsically reliable: a rapidly fleeing pigeon can’t take off without producing it, and a routine take-off sounds markedly different. Having a dependable danger signal helps the population survive, and so the humble pigeon lives to fight another day.

As for me, the answer to my pigeon’s unnerving silence was found under the kitchen cabinet two days later.

In Other News

• If you like ✨ science ✨ and want to learn even more about pigeon noises and alarm signals, the two main sources used in this article are Sounds of Modified Flight Feathers Reliably Signal Danger in a Pigeon and Specialized primary feathers produce tonal sounds during flight in rock pigeons. Sadly, while there are many studies on vocal communication in birds (like song or calls), non-vocal communication is comparatively under-researched.

• Last week I had the pleasure of interviewing Beth Shapiro, the author of How to Clone a Mammoth and the Chief Science Officer at Colossal Biosciences, for the upcoming pigeon book. Now I’m seriously considering writing a newsletter issue on the dodo, the passenger pigeon, and the science of trying to bring them back. A bit outside of our usual scope but too good to pass up on.

• Do we want a “rats with wings” issue? I feel like it has been debunked so many times that continuing to beat this particular dead horse would not be useful, but maybe someone would still benefit from a comprehensive explanation of what diseases pigeons can and cannot transmit to humans. Let me know!

• Pupa is nesting again, and this time she really took to pipe cleaners as her favorite nesting material. We curl them into tiny spirals for her, so they’re bright, fluffy, and make for absolutely gigantic nests.

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B. F. Skinner did:

Pigeons are the city’s most familiar and least understood birds. You have probably seen them on most days of your life, but no matter how much you think you know about them, I promise you there’s more.

Pigeons have been subjects of art, religious symbols, sources of food, postal workers, psychology research assistants, and decorated war heroes. They can learn to spot tumors on mammograms or tell Monet and Picasso apart. They are our noisy little neighbors—and, if you let them, loyal companions.

Once a month, I’ll send you a letter that will make you look at the same city streets and see more than you did before: tales of survival, acts of bravery, and never-ending drama, all hidden in plain sight.

This newsletter is also a companion to my upcoming book about pigeons. Each issue will include book news and little extras that won’t make it into the final pages: interviews with pigeon keepers or scientists, lesser-known pigeon facts, and early sketches of the book illustrations drawn by Joshua Barkman of False Knees.

If there’s one thing I could ask from you besides subscribing, it would be this: don’t be a stranger! Reply to the newsletter or message me on any of my socials. I’m always happy to read your questions, comments, or favorite pigeon stories.

Happy to have you here,
— Ed

P.S. The more people know about the newsletter, the closer we get to making everyone fall in love with pigeons again. Tell your followers, your friends, your mortal enemies, or your platonic social media crush—every little bit helps!

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