Birds of a feather -

Birds of a feather

Crows are smarter than we think, and more like humans than we care to admit


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    IT’S ALWAYS BEEN complicated, the relationship between humans and corvids, as scientists call the 40-plus species of crows and ravens scattered about the world. As trickster figures, agents of wisdom or harbingers of doom, corvids are a constant presence in myth and art—one of the latest examples being Calgary author Clem Martini’s superb children’s series, Feather and Bone: The Crow Chronicles. But most species are not pretty to look at, and many are downright ugly to hear, like gates on rusty hinges swinging in the wind. Worse, corvids eat almost anything, including what we very much wish they would not, like our dead, our grain, and baby songbirds. Hence the word “ravenous” to describe all-consuming hunger. Crows roost in mobs of up to two million, fouling the surrounding area and making nearby humans very nervous. So, for all the wary respect they inspire—it’s no accident that a group of crows is known as a “murder”— we have also shot, poisoned and even dynamited them. In Oklahoma alone during the Great Depression, 127 blasts killed 3.8 million crows.

    It all adds up—in the judgment of biologist John Marzluff, co-author with artist Tony Angelí of the forthcoming In the Company of Crows and Ravens—to a kind of human-corvid co-evolution. That’s still a controversial concept, but as Candace Savage’s entrancing Crows: Encounters With the Wise Guys of the Avian World shows, even those scientists who are uneasy with the idea of corvid consciousness grant that crows are intelligent enough to make the concept plausible. And how smart they are has only recently become clear.

    By any reckoning corvids talk: ravens have 80 different calls, and captive individuals greet their human warders with different sounds, presumably names. Crows make tools out of whatever is at hand, including bending hooks at the end of twigs and wires to pull food out of hard-to-reach places. They remember their persecutors. Marzluff, a University of Washington professor, notes that the crows on his campus know him as someone who captures and bands their young. Although they walk placidly among the 40,000 other humans who daily cross their territory, university crows let off loud warning cries whenever Marzluff arrives. He now tries to alter his appearance each time he climbs to a nest.

    In Seattle, experiments have shown that crows have learned to recognize the Golden Arches logo as well as any human preschooler. Offered a choice of the same fries inside a McDonald’s bag or a plain wrapper, the majority vote with Justin Timberlake. Along one Japanese highway, crows wait at traffic lights for cars to stop, and then place walnuts in front of tires so that humans can do the hard work of cracking the shells open. First documented in 1975, this behaviour has now spread for several kilometres along the road. That means crows can learn, and quickly; what’s more, since friendly drivers have taken to aiming at ill-placed nuts, crows evidently can teach too.

    Corvids pair-bond for life, and cheat on their spouses. They work together for common goals, and lie to one another about food caches. Crows care for their injured and mourn their dead; quite possibly, Marzluff reports, they also execute wrongdoers in the flock. And corvids play: young crows race one another through the air, while ravens have been seen bodysurfing down snowy hillsides in Maine. In fact, for creatures that last shared a common ancestor with humans some 280 million years ago, they are an awful lot like us.

    Even the astonishingly eclectic crow dietsome 650 food items have been found in their stomachs—is just an extreme version of our own, itself one of the most wide-ranging and wasteful in nature. When food is abundant, crows can be picky eaters: in Manitoba, where garter snakes are plentiful in spring, a crow will kill one but eat only the liver after making a deft, TA-inch incision in the snake’s side. When times are hard, though, crows do not turn up their beaks at otter dung or human vomit. Not that times are ever really hard for crows in modern North America, a continent now blanketed in corn, garbage and roadkill. (As American writer Ian Frazier’s satire Tomorrow’s Bird puts it, crow prosperity is based on “their nationwide control of everything that gets run over on the roads.”)

    A cast-iron stomach does confer considerable evolutionary benefit, of course, but what really fuels corvid success is their giant bird brains. As a proportion of body size, crow brains are at primate levels—Marzluff calls them “flying monkeys.” And it’s speculation about that remarkable intelligence that has moved crow research to the leading edge of evolutionary science. Early humans and ravens interacted for hundreds of thousands of years, with the sight of gathering birds alerting our ancestors—as much scavengers as hunters—to dead animals. Inuit traditions even indicate that ravens, which require other animals to kill the meals they scavenge, sometimes led humans to hunting opportunities so that we could bring down the game that fed both species. Raven thieving and caching of surplus meat almost certainly evolved in tandem with human co-operation in food storage and defence, according to Marzluff. And raven influence may have played a role in domesticating northern wolves, which still routinely lose up to 20 kg of meat per kill to the birds. Maybe, Marzluff suggests, some wolves opted to become dogs in part because the raven competition was too tough.

    As humanity turned to agriculture, crows became the most significant corvids for us. Their new grain diet kick-started a steady population growth that became an explosion in recent decades—an estimated 17-per-cent increase per year before West Nile disease arrived—after we turned North America into a crow smorgasbord (and stopped the dynamiting). The reverse influence, crows’ effect on human behaviour and thought, has been more subtle in modern times. It stretches from training motorists to open walnuts to inspiring the work of scientists featured in Savage’s book.

    Researchers into intelligence are now turning away from genetic relationships and the concept of animals sharpening their wits in the eternal battle of predator and prey. Instead, they seek the roots of conscious awareness in complex social lives, where an ability to learn new behaviour allows individuals to gain evolutionary advantage through interaction with each other. Crows and humans both, to a T. Our species may not be biologically related, but our behavioral resemblance may be only natural after all.

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