Timeless Flight

Bird watching is one of the developed world’s most popular pastimes because the 10,000 or so species we have left on our planet are amazingly diverse in size, colour, shape and lifestyle. This evolutionary splendour, whether perceived that way or not by birders, can be viewed easily in our backyards and parks, or for the more adventurous, on bird-watching expeditions. The questions of “how” and “why” occur to many curious birders and have inspired hundreds of scientists, including Charles Darwin, to devote their lives to unravelling the mysteries of how birds evolved their many adaptations for flight, reproduction and survival.

Ten Thousand Birds: Ornithology since Darwin, by Tim Birkhead, Jo Wimpenny and Bob Montgomerie, is a detailed review of the history of ornithology and chronicles the major breakthroughs in the past 150 years and the people who accomplished them. Why undertake such a lengthy and comprehensive review? First, these innovative studies on birds had a broader impact on our understanding of nature and science during the 20th century. Second, much of this history has been buried under an explosion of scientific publications in the past few decades, making it difficult for even the most conscientious researcher to appreciate the deep history of their own field. Birkhead, Wimpenny and Montgomerie go beyond the usual cast of characters and find clever studies published by little-known scientists who were often overlooked or ignored by the big players even in their time. This book was written primarily for a scientific audience, but there is also much of interest to an attentive and patient non-specialist.

Chapter 4, “Ebb and Flow,” is a case in point. For centuries, animal migration has been one of the biggest mysteries of the natural world. It seems unbelievable that little birds can fly many thousands of kilometres to their southern homes, survive dangerous crossings of mountains, deserts and oceans, and return to exactly the same place they started from. Why do they bother? How do they navigate? How do young, naive birds make their first trip? How did scientists figure out the answers to these questions? Birkhead, Wimpenny and Montgomerie explain that the first studies of migration were done in the late 1800s at lighthouses and lantern ships, where thousands of birds could be observed at night, many falling victim to collisions with these obstacles. Bird-banding studies began around 1900 with the hope that birds carrying numbered leg bands would occasionally be recovered later in their journey, revealing migration routes and destinations. In 1907, Hans Christian Mortensen banded 102 migrating Eurasian Teal on the west coast of Denmark and two were recovered more than 1,000 kilometres away in Ireland and southern Spain. This needle-in-the-haystack approach is still hugely popular, and hundreds of thousands of birds are banded worldwide each year.

Bird banding set the stage for the first “displacement” experiments, which moved breeding seabirds far from their colonies, even to entirely novel places north of their breeding range, and showed the birds could easily and quickly navigate back. Subsequent innovations in this field often came from new technology such as radar to detect migrating birds, following migrating birds via airplane, testing migration orientation in the lab using special funnel cages that record the birds’ footprints, and, most recently, tracking individual birds over their entire journey using satellite or light logger devices. Thanks to these pioneers, we now know that birds use multiple navigation systems (sun, stars, landmarks, magnetic fields, polarized light) and that much of migration behaviour is genetically inherited. Even so, the amazing journeys revealed via direct tracking still amaze scientists. Bar-tailed godwits, shorebirds that breed in the Arctic, fly non-stop for 10,000 kilometres, over nine days and nights, from Alaska to their winter quarters in New Zealand.

Not all chapters in Ten Thousands Birds are easy reading. The detail on individual studies and people is impressive, sometimes several “textbook” pages each, and can be daunting at times. A scholar may want to read every word, while a layperson will want to skip around the book to find interesting biographies and stories—there are plenty to choose from.

Many of the scientists profiled in the biographies at the end of each chapter say they have shifted their energy and time away from the fundamental and curiosity-driven research on birds to the more practical and depressing reality of bird declines and extinctions. This is because bird declines are so well documented, affect so many species and point to a bleak future. A shocking 13 percent of all birds on the planet, which amounts to about 1,300 species, are threatened with extinction. In Chapter 11, “Tomorrow’s Birds,” Birkhead, Wimpenny and Montgomerie say “it is sad that the exponential growth in our understanding of the biology of birds during the last century … has been accompanied by an exponential decline in numbers.” What we would now consider to be shocking was routine in the early 1900s, including the mass slaughter of egrets to collect feathers for ladies’ hats, -industrial-scale removal of eggs from albatross on Laysan island and hunting the flightless great auk to extinction. The damage would have been far worse today if it had not been for early pioneers in conservation who shut down the hat trade, created the Migratory Bird Treaty to protect birds, lobbied for public lands to be set aside as nature preserves and revealed the devastating effects of pesticides on birds and wildlife. Birkhead and his colleagues also reveal the passion and dedication of many present-day ornithologists whose Herculean efforts have saved individual species from the brink of extinction—including the California condor, whooping crane and kakapo (a giant, flightless parrot from New Zealand). The book ends with a sad commentary on the future of ornithological research: “as global bird numbers continue to decline, the pursuit of knowledge for its own sake may seem like a bizarre luxury.”

Delving into the details of the evolution, ecology, physiology and behaviour of birds can be rewarding because it empowers you to enjoy nature even more. A birder watching a black-capped chickadee at a backyard feeder in winter may see a cute, tuxedo-clad bundle of energy. An ornithologist would see a social network of dominant and subordinate birds, well-insulated survivors who use the energy-saving trick of torpor to lower their body temperature on the coldest winter nights, and future philanderers who in spring will eavesdrop on the dawn chorus and sneak off-territory to mate with better males from next door. How can we not be awed by the world of the chickadee? There is more to nature than attractive birds and peaceful scenery. There is a complexity and deep evolutionary history that teach us what nature is really all about and why it is worth saving.