How Birds Rest, Roost, and Sleep and How We Disturb Them

Source: Denitsa Kireva / Pexels

A few weeks ago when I was out cycling with some friends, we saw a few birds who looked like they were sleeping. Someone asked me what they were doing, and I said they were resting or sleeping but I'd never thought much deeper about how birds sleep. Now, after reading Roger Pasquier's new and highly original book titled Birds at Rest: The Behavior and Ecology of Avian Sleep, I know a lot more than I did and have a much deeper appreciation for all that science can tell us about what's happening in a bird's body and brain when they're napping or sleeping. All in all, there's no single answer about avian sleep patterns. Some birds sleep briefly with a half-awake brain, while others spend long cold nights in torpor, and some can sleep while flying. Here's what Pasquier had to say about his incredibly interesting book, which also is a compendium of the behavioral ecology of numerous species of birds.

Marc Bekoff: Why did you write Birds at Rest?

Roger Pasquier: In my previous book, Birds in Winter, I had to discuss how birds get through long, cold nights. That got me thinking of how complex—may I say sophisticated?—are the ways birds sleep, all through the year. The only book on the subject was from 1989, with lots of good information, mostly from direct observation. But, since then, technology has advanced so much that it is now possible to track birds remotely, revealing whether they are flying or still, on land or in water, awake or asleep.

I thought there could be a book on this, so dove into research. I discovered that avian sleep and roosting habits are indeed sophisticated, and very different from those of humans and other mammals. It became a fascinating journey.

Source: Princeton University Press

MB: How does your book relate to your background and general areas of interest?

RP: I have been a birdwatcher since I was 7, and I have always been attracted to the spectacles of birds coming to their roost. By age 11 or 12, I was detouring on my way home from school during the shortest days of winter to watch the flocks of starlings that then roosted by the thousands on the Metropolitan Museum. Ever since, I have gone out of my way at dusk to watch flocks of birds at their roost. (Psychology Today readers may find fodder for analysis here!) There’s a lot you can see, even in New York. Perhaps I should say “especially in New York,” because some birds commute from suburbia to roost here, where there are fewer predators as well as, in winter, slightly warmer temperatures.

More broadly, the ecology and behavior of birds have been my lifelong focus, and—for any creature—you need to understand how, when, and why it rests as well as the active phases of its life.

MB: Whom do you hope to reach?

RP: Anyone who enjoys looking at birds, because some of what I discuss is readily observable. But since even jellyfish and clams, not just animals with a brain, sleep, I think anyone interested in any aspect of nature will enjoy learning how birds have evolved their unique sleep habits to match their intensely energetic lifestyle

MB: What are some of the major topics you consider?

RP: I begin the book with a discussion of the evolution of sleep in the animal kingdom and its benefits, focusing of course on birds and the complexity of their lives. We now know, using electro-encephalogram equipment, that birds, like us, have both slow wave and rapid eye movement sleep, but their sleep bouts are in very short intervals, of several seconds or a few minutes, after which they wake to scan for predators and then revert to sleep. (Whether birds dream is still an open question!) As another adaptation to vigilance, birds can sleep while shutting only half their brain at a time, keeping the other half and one eye awake, to respond to danger. And, some birds can do this even while flying. Other forms of rest, such as quiet time during the hottest hours of the day, are widespread.

The energetics of sleep—how to maintain a high body temperature; the advantages, especially to small birds, of lowering it; and the thermal benefits of different roosting sites lead to the book’s other major focus—where do birds sleep? Most are solitary, some in pairs or families, while others gain advantages of warmth, safety, and even social needs like finding a mate by joining in flocks, not to mention guidance on where to get breakfast the next morning. Readers of Psychology Today will be interested to know that many of these decisions involve forethought.

Source: Courtesy of Margaret LaFarge

People have had their impact on roosting habits. Some birds are hunted at their roost or persecuted to drive them away. Artificial light and noise have changed the sleep habits of birds nearby causing them to get up earlier, with less sleep. Even climate change is having effects, by eliminating roosting sites and spreading avian diseases carried by insects now moving to areas previously too cold for them.

MB: How does your book differ from others that are concerned with some of the same general topics?

RP: No book since 1989 has focused on avian sleep, and immense amounts about the basic mechanics of sleep as well as the behavior of birds when they are hardest to observe have been learned since.

MB: Are you hopeful that as people learn more about the fascinating behavior of birds they will be more likely to connect with them and respect their lives?

RP: I certainly hope so! When you learn the many ways birds have evolved to survive and the elegance, if you will, of their behavior and physical adaptations, I think it should inspire a reverence for life and the will to do more to protect it.