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Some Crows Are Birds, Others Are Artists

Headshot of Christian Rutz
Christian Rutz shows off the tool-making ability of New Caledonian crows. Photo by Kevin Grady/Radcliffe Institute

In New Caledonia, Christian Rutz found a match for his adventurous mind.

Christian Rutz might have become an architect, like his father, and spent his life designing grand buildings for sophisticated city dwellers instead of tiny cameras for grub-hungry crows. 

Behold a man with no regrets.

“When you see these birds for the first time, it really blows your mind,” says Rutz, a professor of biology at the University of St Andrews, in Scotland, and the 2019–2020 Grass Fellow at the Radcliffe Institute. “You’re completely unprepared for what’s about to happen.”

What’s about to happen is exceedingly rare—perhaps unheard of—in the nonhuman animal kingdom. The New Caledonian crow, known for using stick tools to extract meals from larva-infested logs and tree branches, is about to exhibit an even higher level of technological prowess, in the form of hook making. Bad news for centipedes, crickets, and other invertebrate prey. Good news for a young Oxford scholar on the lookout for his first post-PhD adventure. 

“It was fun to see them in captivity—it was amazing—but I had an instantaneous urge to go to New Caledonia to see them in the wild,” says Rutz, recalling an early glimpse of the crows at an Oxford lab in 2005, by which time he’d firmly resolved that science, rather than a near-equal passion for architecture and fine arts, would occupy his professional life. (“I realized it wasn’t possible to do science on the side.”) 

A three-year grant in hand, Rutz traveled to the South Pacific island of New Caledonia, nearly 10,000 miles from his hometown of Hamburg, Germany, to see the birds in their natural habitat. His plan was to build on insights produced by Gavin Hunt, whose breakthrough study on the crows’ hook-making ability had been published in 1996. “A fantastic adventure,” Rutz says now of his introduction to New Caledonia. And yet the ghost of failure lingers in his mind. A little less trust in his intuition, or a rush to set up camp—Rutz’s team scouted for weeks before establishing a study site on the west coast of the island—might have doomed the effort before it got started. 

“I was really strategic about how to launch that project,” he says. “I knew that this was an opportunity to lay the foundations for an ambitious long-term study.”

For all their spectacular ingenuity, the crows, fast-moving and shy of humans, resisted scientific stardom. Rutz’s solution borrowed from his experience as a teenage electronics geek. In pursuit of a crow’s-eye view, he and his team, with help from a former BBC special-effects cameraman, set their sights on a crow-mounted video camera. The result was a machine the size of a USB stick. The reception was mixed. “Brilliant idea, but this won’t work,” Rutz heard more than once from peers. In one of countless failure hypotheticals, the devices malfunctioned; in another, the movie came back a dud. Instead, the world gained a data-rich picture of New Caledonian crows’ tool use, as reported in Science in 2007, and Rutz, proud co-developer of the first cameras attached to free-flying birds in the wild, moved forward an avid, if calculated, risk-taker. 

“I always have something cooking in the background which is really ambitious, blue skies—if it works it’s a big deal, if it fails it fails completely,” he says. “I like that.”

The hooks were his next target. The crows make them from a specific plant species, executing a series of precision cuts. If a tool maker moves too quickly, its haste shows in the quality of the hook. But even birds can be perfectionists. “The most-skilled crows, when something isn’t quite right—for example, because they removed too much material, or they misjudged the stem and it’s not as good as they thought—they simply discard the tool,” Rutz says. “They don’t do second-best.”

The researchers were especially keen to understand the benefits of the finished product. Compared with the crow bearing only a stick, how much more efficient is the hunter armed with a hook? The unscientific answer: whoa. Up to 10 times as efficient, a series of experiments demonstrated. In a 2018 paper in Nature Ecology and Evolution, Rutz described one of his most thrilling discoveries to date—“We had no idea just how large these effect sizes would be”—while also presenting key evidence in support of “cumulative culture” in New Caledonian crows. “If one group of crows has a clever idea and invents a new design feature, such as a hook, it seems this innovation isn’t lost, but it’s passed on to another generation,” he says. “Over time, these tools seem to become ever more complex and ever more efficient.” 

No bird will design a skyscraper anytime soon, but the ability to accumulate and transmit information across generations would establish the New Caledonian crow as an extraordinary candidate for illuminating human technological progress, not least because of the vast evolutionary gulf—hundreds of millions of years—separating us from the birds. As Rutz explains: “It’s not a primate; it’s a bird. This phylogenetic distance really adds value. I can be completely confident that what we see in these crows cannot be traced back to a common ancestor with modern humans. It must have evolved independently.”

Which is not to say that New Caledonian crows are beyond compare. In research that made the cover of Nature in 2016, Rutz and his colleagues described tool use in Hawaiian crows, whose straight bills and forward-pointing eyes are a near-match to the features of their New Caledonian cousins. As non–hook makers, the Hawaiian species may provide “a window into the evolutionary past of the New Caledonian crow,” Rutz says. A multiyear study awaits, next in line behind a search, backed by the National Geographic Society, for more undiscovered tool users. 

But Rutz’s most immediate concern is relief from immediate concerns. “Radcliffe is the perfect bubble for pursuing blue-sky ideas,” he says. “You can be bold. You can explore things that lead to dead ends, and nobody’s going to complain.” Accordingly, along with the time to write up a 20-year data set on New Caledonian crows, he sees in his fellowship an incubator for his next grand design. “I have maybe five to six things I’m looking at, at the moment—big ideas. I’m pretty sure most of them won’t work. But I only need the one.”

Ryan Mulcahy is the editor of Radcliffe Magazine.

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