|The Mind of the Raven|
|Investigations and Adventures with Wolf-Birds|
by Bernd Heinrich
Posted: June 16, 2000
Backyard Biologist Tests Raven IQ
Since prehistoric times, ravens have been revered and reviled. Poets wrote about them, native people worshipped them and European settlers attempted to eradicate them.
They were kept in the Tower of London because their vocalizations were thought to warn of approaching danger. Odin, the ruler of the Norse gods, kept two wolves at his side and a raven on each shoulder. The Vikings eagerly welcomed ravens as an omen of victory. The Inuit believe ravens help them hunt caribou, polar bears and seals by dipping their wings in the right direction.
Then there's their downright peculiar behavior: reports of ravens hanging from their feet, sliding in snow, flying upside down, rolling in mid-flight, tugging at wolves' tails and defending their nests with rocks.
In "Mind of the Raven: Investigations and Adventures with Wolf-Birds," biologist and raven fanatic Bernd Heinrich sets out to investigate the motives for these odd behaviors by attempting to separate what is pre-programmed, what is learned, and what is insightan indication of intelligence.
Heinrich has studied ravens for 16 years, but his history with the birds dates further back. As a boy in post-World War II Germany he kept a pet crow, and as a graduate student at UCLA in the 1960s he housed two tame ravens in his Westwood apartment. He wanted to study them but was advised (jokingly) never to study an animal smarter than himself.
Instead he studied protozoa, moving on to caterpillars and later bees. His book "Bumblebee Economics" is considered a scientific classic. Heinrich is a professor at the University of Vermont but does most of his raven-watching near his hand-built cabin in Maine. In 1994, he published "Ravens in Winter," his first attempt to "make sense" of ravens.
The common raven, Corvus corax, is the world's largest crowfour times heavier than the American Crow. No other bird in the world has a wider distribution or shows more adaptability. They occupy an extraordinary geographical and ecological range, from the Arctic Circle to the mountains of Central America.
While most of us couldn't tell one raven from anotherbig, black, noisy, looks like a crow, right?Heinrich believes no two are alike. Ravens, like humans, are not "pre-wired" (like, say, ants or bees). Their behavior is spontaneous and evolving as they solve life's problems. "I have often been startled by their enigmatic and seemingly contradictory responses. But the poetry of biology resides hidden in opposing tensions, and the often arduous fun comes from trying to reveal it," Heinrich writes.
And fun he does have. Heinrich, a seasoned marathon runner, climbed two large pine trees in a windstorm to retrieve four baby ravens, which he is raising in his backyard in Maine.
He derived an idea to test their intelligence from a copy of "Ranger Rick" magazine, a present to his then young son, Stuart. In the magazine, a short article described the clever things you can watch birds do, like pulling up food suspended by a string. Heinrich theorized that if a rare raven could figure out how to pull up fooda 10-consecutive-step processwithout a lengthy trial-and-error period, that it might indicate intelligence. "That is, insight might precede or accompany learning to produce the same behavior."
This simple experiment allowed Heinrich to reduce the possibilities of random chance and of genetic programming that would have coded this very specific unnatural behavior. Since his ravens were raised in captivity, Heinrich was assured they had no prior experience and so could not have learned the behavior.
If they could solve the problem, it would prove insight. Well, the ravens aced the test. Not only did the first raven perform the entire sequence with nary a fumble, he dropped the meat when chased off by Heinrich instead of trying to fly away with it. "The significance of the remarkable behavior of not flying off (with the meat) was that it was a new behavior that was acquired without any learning trials. They acted as though they had already done the trials. The simplest hypothesis is that they hadin their heads."
Heinrich does not restrict his detective work to his backyard. He flew to Oberhausen, Germany, in response to a letter he received from a medical doctor who regularly allows his raven, Jakob, to roam 'free' in his apartment. "(This) was an opportunity I could not pass up . . . I wondered how fast a raven would disassemble an apartment . . . three minutes, maybe five."
If it is true, as some speculate, that the capacity of an animal to cause damage is proportional to its intelligence, then ravens are geniuses. To his surprise, Jakob destroys only junk mail and has left the doctor's museum-like apartment intact.
Jakob eats what the family eats, watches television with them (Jakob finds a raccoon on the screen very upsetting), bathes regularly and demands caresses every night.
Heinrich watched Jakob, asked questions and took notes. At one point, Jakob insisted, with a "mighty heave" into Heinrich's thigh, that he hand over his pen. Heinrich, ever agreeable to a raven's demands, complied.
Heinrich speculates that Jakob does not destroy the apartment because he had remained in his cage for his first two months there. During that time, he had seen most of the apartment and his interest in its contents had faded. It was only new things, like the pen, that interested him. "The corvid line of birds all share this capacity of curiosity. It is their trademark. One wonders if it is the key that has allowed them to flourish and diversify."
Wolves may have also had a hand in their survival. During a trip to Yellowstone National Park, Heinrich observes that ravens arrive at all wolf kills and immediately begin feeding. However, they avoid carcasses where wolves are absent.
Though confusing behaviorwhy wouldn't ravens take advantage of an easy food source?it fits a pattern Heinrich had observed before; that ravens invariably choose to be with the wolves. "Maybe (ravens) had evolved with wolves in a mutualism that is millions of years old, so that they have innate behaviors that link them to wolves, making them uncomfortable without their presence."
Ravens need wolves for several reasons: they rely on wolves to kill, to open carcasses (ravens are incapable of tearing open a carcass) and to possibly overcome their innate shyness of large food. Wolves also need ravens. Ravens have been reported to alert wolves to potential food sources and to danger.
Wolf watchers have historically taken ravens and wolves for granted, "so much is taken for granted that further comment, or data, have seemed superfluous," Heinrich writes. Heinrich successfully convinced Yellowstone biologists to include studies of ravens with their studies of wolves. As the book went to press, initial surveys indicated ravens always showed up at wolf kills and fed with the wolves within minutes. In the twenty-five cases where provided meat was unattended by wolves no ravens fed within the hour of observation.
Obviously there is much left to learn about ravens. "Mind of the Raven," beautifully designed, is a great start. Each chapter begins with a black-and-white photo, one of which includes a picture of Heinrich's son as a baby surrounded by Heinrich's last batch of raven babies. His sketchesmuch more sophisticated than sketches from "Raven in Winter"are included within each chapter. At times his writing rambles, but for the most part, his enthusiasm is so grand that even the disinterested can't help hoping Heinrich will continue unearthing clues to the mystery named Corvus corax.