Why Birds Do What They Do

March 27, 2023

A review by Kyle Carlsen

Understanding Bird Behavior: An Illustrated Guide to What Birds Do and Why, by Wenfei Tong

Princeton University Press, 2020

224 pages, hardcover

ABA Sales–Buteo Books 15037

One of the best parts of watching birds is observing their behavior. Birds are rarely boring. They fly, forage, interact with each other and with their environment, court, raise young, deal with danger, and undertake mind blowing migrations, just to name a few of the fascinating things birds do. Understanding Bird Behavior: An Illustrated Guide to What Birds Do and Why introduces readers to much of what makes birds so special in a concise and attractive volume.

Author and biologist Wenfei Tong brings a lot to the table in her second book on the behavior of birds. She has studied both mammals and birds in Africa, Europe, and North America and has worked as a natural history guide and public speaker. Her first book, Bird Love, focused heavily on how birds mate and raise young. Understanding Bird Behavior does include chapters on courtship and family life, but it also explores how birds find food, why they form nonbreeding relationships, how they respond to threats and danger, and how they adapt certain behaviors based on climate change. Tong walks us through classic examples and the latest research to offer the reader an overview that demonstrates the diversity and adaptability of birds.

This book is by no means comprehensive. Some of the studies or examples are given only a few sentences. Instead, this volume functions much like a college survey course: It presents an excellent summary of a complex subject that leaves you wanting more and inspires ideas and paths to be explored further. The prose is engaging and accessible. The illustrations are many—nearly every page features at least one photo, painting, or drawing—and support the text in a pleasing fashion. The fusion of art and science seems to complement what this book is about, which, according to the author, is exploring why birds behave the way they do and “how their interactions with each other and with humans inspire and influence our view of life.”

Throughout the book is example after example of how birds have evolved, and continue to evolve, featuring species and studies from around the world. Some of these examples may be well known to seasoned birders. Other examples are from recent research and are probably not as well known. In the chapter on finding food, Tong discusses how different types of Red Crossbills have subtly different bills adapted to prying apart the cones of conifers. In the case of lodgepole pine specialists, Red Crossbills that coexist with the red squirrel, another pinecone predator, have smaller bills than the birds that occur in areas with no squirrels. This is because these squirrels prefer large cones with more seeds, and so most of the pines produce smaller cones with fewer seeds. However, there are no squirrels in the South Hills of Idaho, and so the lodgepole pines there are producing larger cones.

Tong explains, “This in turn has driven the resident South Hills crossbills to evolve much larger bills to open the larger cones, and so on, in an escalating coevolutionary arms race. As a result of coevolution with their food, the South Hills [crossbill type] is so distinct in size, sound, habits, and genetics that it is now a distinct species, the Cassia Crossbill.”

We also read about how humans and bird feeders have had an impact on bird behavior and evolution. Some species, such as the Northern Cardinal and Anna’s Hummingbird in the U.S., have expanded their ranges in recent years, seemingly in part because of supplemental feeding by humans. Other species, such as the Great Tit in the U.K., have evolved longer bills in populations that use bird feeders, suggesting that “every time we feed birds, we could be changing not just their diets, but also their behavior—and ultimately, contributing to their evolution.”

A drawback of the book is the lack of bird species’ scientific names, especially since the author mentions a variety of species from across the globe. There is also the author’s occasional habit of referencing a study or an individual researcher without clearly citing the source; a selected bibliography is included, but providing a more comprehensive list of references would have enhanced the content significantly.

These downsides should not discourage birders from reading and benefitting from Understanding Bird Behavior. The book has much to offer. We birders would do well to think more about behavior and about how what we are observing fits into the evolutionary story. This book inspires that. It is a useful resource for anyone interested in knowing birds better.


Kyle Carlsen is a freelance writer and editor from Ohio currently living in northern Colorado. His writing has appeared in many books and magazines. A lifelong birder, his favorite birds (in no particular order) include Grasshopper Sparrow, Blue Jay, and Northern Pygmy-Owl.