How Birds Fly: The Science and Art of Avian Flight, by Peter Cavanagh
Firefly Books, 2024
336 pages, hardcover
ABA Sales–Buteo Books 15524
Perhaps for most birders, the bird in flight too often means the end of an observation. A warbler flits off through the understory; a hawk glides over the tree line; the shorebirds or ducks lift and tear off across the marsh; and it’s on to the next bird. But how often do we stop to wonder, how in the world do they do it?
Peter Cavanagh’s blend of qualifications makes him uniquely suited to answering this question in his 2024 book, How Birds Fly: The Science and Art of Avian Flight. A British native, he received his doctorate in anatomy and biomechanics at the University of London’s Royal Free Medical School. His passion for bird photography and bird flight evolved from his love for the outdoors, his experiences in the air as an instrument-rated private pilot, and his extensive professional training in the science of locomotion. An accomplished bird photographer whose photos have been included in Audubon’s Top 100 Bird Photographs of the Year, he has spent over a decade photographing birds in flight on every continent, amassing an archive of over 800,000 images.
In his previous photographic book, 100 Flying Birds: Photographing the Mechanics of Flight (2020), Cavanagh curates a selection of personal favorite images, sharing for each photo the backstory and technical details of taking the picture, tales of his travel to far-flung destinations, and bird facts about the species shown.
“In my mind, there is no contest between a photograph of a stationary bird and a flight shot—the flight shot is almost always the hands-down winner,” Cavanagh notes in the preface to How Birds Fly. “The fragile span of outstretched wings and the arc of a graceful flight path are irresistibly beautiful. Flight is the essence of bird life, and capturing it in a few megapixels is a privilege and a joy.”
In How Birds Fly, Cavanagh shifts his focus toward bird flight itself. He states in the book that his goal is to “pull back the veil of mystery surrounding bird flight and explain its many facets in a way that is accessible to all people who love birds.” Two introductory chapters cover the “whys” of avian flight (to escape from predators, hunt prey, extend range, find a mate, defend territory, and migrate) and current theories on the evolution of flight and the origins and radiation of modern bird species around the planet.
The first two-thirds of the book detail all aspects of the mechanics of bird flight. Chapter 3 covers the relevant facets of bird anatomy—wing structure, tail, and feathers—as well as the unique characteristics of bird physiology (hollow bones attached to air sacs, specialized metabolism in muscles, etc.) that facilitate flight. Chapter 4 lays out the aerodynamics behind bird flight. Cavanagh skillfully balances technical terms and concepts with familiar parallels with human airplane flight and avian examples. Principles are expanded and illuminated with drawings, charts, diagrams, photos (some enhanced via graphics or enlargement) that feature detailed but comprehensible captions rounding out the discussion. For instance, an attractive, full-page color-coded graphic compares feather groupings (primaries, secondaries, coverts, scapulars) and wingtip shapes of birds whose flight characteristics, sizes, and lifestyles are drastically different.
This information is more technical than what is found in most bird books, which tend to focus on bird identification, biology, and behavior, but a close reading of the text and taking the time to study the photos and illustrations here deliver a big payoff. These two chapters lay the foundation for the in-depth discussions about gliding, soaring, and flapping, as well as takeoff, landing, and maneuvering in subsequent chapters. These two and all the other chapters conclude with an engaging “From the Lab” feature highlighting a relevant published research paper that shows how avian research is done.
The greatest strength of How Birds Fly surely lies in Cavanagh’s eye-popping photographs of a wide range of birds that serve to illustrate his text. He treats his reader to incredible spread-wing photos in which every feather is visible: photos showing various types of feathers working at points along wings to guide and control flight; photo sequences displaying running takeoffs on both the ground and on the water; and photos of birds diving for prey and birds coming in for feet-first landings to tiny perches. Some photos show how air currents affect lift and trajectory, and a number of others demonstrate the intricacies of flapping, among many, many other subjects. They significantly enhance the learning experience by revealing subtle movements that happen too far away or faster than we are able to observe in real time. The book’s generous 9-by-11–inch dimensions showcase Cavanagh’s breathtaking photographs without making the book too cumbersome or heavy.
The last third of How Birds Fly branches out a bit to cover a few topics perhaps more familiar to birders: specialized flyers such as swifts, hummingbirds, owls, and albatrosses; migration; and flightless birds, including rheas, penguins, and the Flightless Cormorant of the Galápagos. A fascinating chapter explores “bioinspired flight,” or attempts to design or improve devices through copying bird characteristics, like flapping flying robots, 3-D printed artificial feathers, and quieter airfoils with leading and trailing edges patterned off owls’ wings. The final chapter, “Flight Stories,” offers accounts of pioneers of human flight, including Otto Lilienthal, the Wright Brothers, and Leonardo da Vinci, and the birds that inspired them.
In How Birds Fly, Cavanagh most certainly accomplishes his goal of unraveling the mystery of bird flight in an accessible way—a way that turns out also to be enjoyable and spectacular. It will be of interest to birders, photographers, students, and anyone wishing to broaden their knowledge of and appreciation for the wonders of the avian world.
Emily Simon is a retired reference book editor. She volunteers with Detroit Bird Alliance and has contributed book reviews for its quarterly magazine, The Flyway, which she also helps edit. She is also a writing mentor for the ABA Young Birder of the Year. An avid birder for nearly 30 years, she enjoys connecting others to great books about birds, nature, conservation, and the environment.
