Ep. 21 – David Barrie on the wonders of animal navigation

David Barrie in the land of the bogong moth. Bogong moths fly a thousand or more kilometers in their annual nocturnal migration from their breeding grounds in southeastern Australia to high, mountain caves in the Australian Alps. Like migratory birds, these moths rely on the Earth’s magnetic field to guide their routes. New discoveries indicate that the moths also use the alignment of the Milky Way to navigate. Photo by Eric Warrant.

It has been said that the Sahara desert ant, Cataglyphis fortis, is a navigational miracle. These tiny insects live in the barren salt pans of North Africa, where ground temperatures soar to 145 F — too hot for almost any animal to survive. They live underground and leave their nests at the hottest time of day to avoid predators and to forage for food (typically other insects that have died of exposure). To avoid being burned to a crisp themselves, the ants must be as efficient as possible in returning to their nest. How does the desert ant find its way back, sometimes over distances of 100 meters, via the fastest route? The answer, our guest, award-winning author David Barrie writes, is astounding and flat-out humbling. So too is the ingenuity of the scientists who study them. Here, he writes, is “a small insect capable of performing navigational feats that we humans can only manage with the help of instruments.” 

Barrie with a bogong moth on his right thumb in the snowy mountains of New South Wales. “Discoveries about animal navigation can help us recognize what is at risk…” he writes. “Even if our own lives did not depend on the health and vitality of the planet we inhabit, the preservation of the almost infinitely complex web of life from which such wonders emerge is surely an ethical imperative … We must plot a new course.”  Photo by Eric Warrant.

As Barrie writes, the ants determine where they are at a given time by measuring the angles of their turns (by using the sun’s patterns of polarized light in the sky as a compass) and by measuring the distances they travel (by counting their steps, like a natural odometer). They then integrate this information, a process humans call “dead reckoning” and relied upon for marine navigation into the mid-18th century. The ants’ navigational toolkit also includes the ability to rely on visual landmarks, the direction of wind, micro-vibrations, and scent. They can distinguish reliable landmarks from unreliable landmarks, and may even, like bees, make use of “optic flow” – the visual phenomenon in which the scenery around us flows past us at a rate that depends both on how fast we’re going and how far away the scenery is from us. And recent studies indicate they may also orient by using the earth’s magnetic field. Their talents reveal an extraordinary awareness of the environment around them — a form of perception that is far different from our own. These ants are just one of the many animal navigators that Barrie explores in his new book, Supernavigators: Exploring the Wonders of How Animals Find Their Way.

“More than half the human race is cut off from the most sublime spectacle the nature has to offer,” Barrie writes, in reference to the star-filled night sky. “According to recent research based on satellite images, more than 80 percent of the world and more than 99 percent of US and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity … The scourge of light pollution has crept up on us so slowly that hardly anyone realizes how much it has cost us — and it is getting steadily worse. It is damaging to human health, and other animals that depend on natural light for many different purposes, including navigation, are suffering even more from its ill effects … It is a serious environmental problem that receives far too little attention.” Photo by Kit Rogers.

The author Henry Beston famously wrote that animals are “not brethren, they are not underlings: they are other nations, caught with ourselves in the net of life and time, fellow prisoners of the splendour and travail of the earth.” In his book, Supernavigators, Barrie, a former British Diplomat, travels around the globe and through scientific literature, both historic and contemporary, to learn about the extraordinary and still mysterious navigational powers of animals. He meets with the scientists who study the wayfinding skills of birds, butterflies, and more. He returns from these other nations to human society as a special envoy, skillfully describing the stunning array of navigational intelligences of other species — often exceeding our wildest imaginations — and issues a call to better respect and celebrate these animals’ abilities in an era where human behavior is increasingly impeding them. 

Barrie is a Fellow of the Royal Institute of Navigation and has sailed all over the world and made many long voyages. After serving in the British Diplomatic Service, Barrie worked in the arts and as a law-reform campaigner. His award-winning first book, Sextant, told the story of one of the most important human navigational instruments ever created. 

Recommendations:

Souvenirs Entomologiques (“Entomological Memories”) by Jean-Henri Fabre

The Moths of the British Isles by Richard South (two volume series)

Selected Writings by John Ruskin

The Thin Red Line directed by Terrence Malick

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