Rebecca Heisman (published by Harper Collins in the US on 14 March, and by in the UK on 20 April)
QUESTIONS about how and why so many birds make extraordinarily arduous annual migrations – and where they are going – have puzzled us for years. Perhaps they are flying to the moon, speculated 17th-century English educator Charles Morton; others had wondered if, when birds vanished, they might be hunkering down for the winter .
More than three centuries later, scientists are still working to fully unravel the secrets of bird migration. In some cases, what they have uncovered is more surprising than even the boldest ornithologist could have predicted.
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Assessing the progress – and its implications – is the task of science writer Rebecca Heisman’s first book. Flight Paths: How a passionate and quirky group of pioneering scientists solved the mystery of bird migration provides a peek into the drama behind some of the biggest discoveries in migration research.
Heisman punctuates her comprehensive history with a cast of inventive and sometimes obsessive minds, including Bill Cochran, a former electrical engineer from Illinois and part-time ornithologist, who developed a miniature radio transmitter light enough to attach to songbirds in the 1960s.
His decades-long quest to track birds led him into many misadventures, including being misidentified as a drug smuggler. Cochran is a gift for Heisman, who must have had to work hard elsewhere to add colour to what could easily be a technical tale. Her curiosity and descriptions are a boon for all unfamiliar with the birding world. I especially loved her vivid account of trying to find a ground-dwelling bird called a sora.
In its nine chapters, Flight Paths soars through the history of migration research, from counting passing birds against the glow of the moon in the 1950s to the recent advent of wearable trackers the size of jelly bean sweets.
Most people are now familiar with the idea that some birds travel thousands of kilometres seasonally for climate, food or mates, but the scientists first proposing the phenomenon were often laughed out of the room. Advances in technology are finally allowing research to confirm or debunk those early claims.
In the 1960s, ornithologist Ian Nisbet proposed that blackpoll warblers (pictured above) were undertaking a far more impressive autumn journey than anyone had logged. As Heisman reports, Nisbet believed they were making the staggeringly long flight from eastern Canada to South American countries such as Colombia and Brazil.
Some of Nisbet’s peers thought it absurd: how could a bird weighing just 12 grams (the same as an AAA battery) fly so far over the Atlantic Ocean in one go? After all, that would take days of ceaseless flying.
Five decades later, researchers were able to confirm Nisbet’s notion with a device containing a light sensor and a clock to map the migration. This uses sunlight to work out a bird’s latitude and longitude at a given time.
Understanding how, why and where birds migrate is about more than solving a mystery. It is critical for future conservation efforts. Migratory species are especially at risk because they rely on a network of healthy, connected habitats, and the window of opportunity to act is slamming shut. In 2019, a study by the US’s National Audubon Society found that North America alone had lost around a quarter of its birdlife since 1970, which amounts to around 3 billion individual birds. “If we don’t know where birds are going, we don’t have the information we need to save them,” says Heisman.
Flight Paths is a vital wake-up call to birders, ornithological societies and governments.
