A World on the Wing by Scott Weidensaul review – incredible journeys taken by migratory species

Among the mysteries of migration unfolded by the renowned natural history writer Scott Weidensaul in his new book is the song of the male red knot. This rises in reflection of its expanding genitalia – “shrunken and all but functionless” during the months it spends in Australia, then swelling as it flies north towards its Siberian breeding grounds, “ballooning to almost 1,000 times their minute winter size” and pumping testosterone through the bloodstream with such force that “what had been a mild, occasional itch to sing during the weeks of a springtime stopover on the mudflats of the Yellow Sea would become a constant hormonal compulsion in the Arctic”.

He tells an amazing tale of bar-tailed godwits, some of which make “the longest non-stop migration known” south – up to 7,500 miles from the Arctic to New Zealand in a continuous, feverous flight lasting eight or more days. They gather the strength for it by gorging themselves on marine worms on the tidal flats of the Alaskan peninsula, doubling their weight within two weeks and making themselves “so obese that they jiggle when they walk”. What happens next is nothing short of a superhero comic scene. Digestive organs “shrink and atrophy”. Pectoral muscles, heart and lungs all double in size until the godwit is ready for flight. Code-switching, the alternation between languages or speech patterns that is the most natural survival instinct of so many a human migrant, has nothing on the mechanics of metamorphosis that have evolved across our avian counterparts.

I’m not a birder, but Weidensaul persuades me that I could be, and that a greater appreciation of the movement and behaviour of migratory birds might bring me into closer contact with what it means to be a living thing on Earth. How is it that these animals, even at a first attempt, can navigate a hemisphere with such unreal precision? The answer, as Weidensaul relates, might lie in the phenomenon of quantum entanglement with the planet, as wavelengths of blue light excite and split electrons between the eye of the bird and the air they cut through – electron pairs that remain connected, in spite of distance, creating a map of the world in the eye of the bird.

A master storyteller who is also profoundly involved in scientific ornithology, Weidensaul is an active field researcher and has authored more than 30 books including Living en the Wind: Across the Hemisphere with Migratory Birds, which was a Pulitzer prize finalist in 2000.

These years, he informs us, have also been an era of unprecedented boom in the knowledge we possess about the life of migratory birds, driven by new technology, including satellite transmitters, radar systems, crowdsourcing and machine learning – computers that can “listen to the skies”. Reflection of that dynamic interplay – between technology and our understanding of the natural world – is very much the language of Weidensaul’s own song, as he sets about revealing the inner workings of research institutes and conservation centres from the Cornell Lab of Ornithology to the guesthouses of Pangti, in rural Nagaland, north-east India.

Weidensaul communicates so much joy in the sheer act of witnessing and such exhilaration in the advances of the science behind what he sees, that we are slow to grasp the extent of the ecological crisis that he outlines.

Billions of migratory birds, he tells us, have in recent years been “lost to habitat destruction, pesticides, building collisions, cats”. And now the climate crisis – “the big enchilada” he calls it – threatens to disrupt all previous certainties, including prevailing winds, rainfall, habitats and food supplies, that bird migration relies on. “Migrants," él dice, “those that already exist in a fragile balance between distance, time, physiological ability, seasonal resources, and predictable weather”, emerge as a critical frontline in this age of environmental catastrophe.

For all the doom he describes, sin emabargo, Weidensaul has no real gift for tragedy. Each one of his stories, from the rehabilitation of Amur falcons in north-eastern India to the adaptation of Eurasian reed warblers in the face of rising global temperatures, emerges as a celebration of positive human behaviour: patient observation, indefatigable problem-solving and conviviality, cual, like the routes of the birds he describes, extends far beyond the borders of our nation states, connecting researchers, conservationists and local communities around the world in the task of reckoning with our abundance before it’s too late. What emerges is an emphatic statement of confidence in nature’s resilience – a vision of nature as a force that we and our science are irrefutably a part of.

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