A Murder of Crows
Updated: Nov 20, 2020
Humans and corvids share a love-hate relationship
Some months ago, in response to ratepayer complaints, the city of Chatham, Ontario posted a bounty on an estimated 30,000 crows that were haunting uncovered refuse dumps near the city. First an amateur free-for-all was organized, with a prize for the biggest crow shot. When this was unsuccessful, the city decided to hire professional hunters.
Chatham's response to its noisy, scavenging birds is not unique. Recent complaints from livestock farmers that ravens were swarming and killing newborn calves led Germany to put a bounty on ravens. Last year, similar pressure led the Government of Alberta to let ranchers shoot ravens on private land.
No doubt about it, the corvids - crows, ravens, rooks, magpies, and jays - can be a nasty bunch. Ravens have been seen in Yellowstone Park, eating the eyes out of live bison stuck in mud. Yet in fairness, no evidence exists that any corvid anywhere in the world has ever killed a calf or lamb. Evidently there are bucolic myths, as well as urban ones.
Humanity seems evenly divided into those who find corvids fascinating, and those who consider them vermin. This is a genus suffused with paradox. For one thing, corvids belong to the Passerines, or songbirds. What! Larks and orioles, family to a mob whose usual cries are so harsh that the collective for crow is murder? Well, yes: the corvids can speak sweetly when they want to. If they're normally as unmelodious as Brooklyn cabbies, it's because both Brooklynites and birds prefer it that way.
Ravens can in fact produce an amazing variety of sounds. Not only can they hum, sing, and utter human words: they have been recorded duplicating the noise of anti-avalanche explosions, down to the "Three...Two... One" of the human technician. These talents of mimicry reflect the general braininess of corvids - which is so high that by most standards of animal assessment, it's off the scale.
It's astonishing how many people cherish a story to this effect. Ravens who pull eagles' tails, then evade the enraged raptors by doing barrel-rolls. Ravens that systematically fish trout streams, moving from pool to pool. Two ravens working as a tag-team to swipe food from an intellectually outclassed dog. Ravens that deliberately cover streetlight switches on cold days, keeping the lights on to warm their feet. Ravens in Whitehorse who extend their foraging range by hopping on the backs of pickup trucks.
Lay people have long known how smart the corvids are; science has arrived at the same conclusion more slowly. One sympathizes with the scientists, for their training duns into them that things are not always what they seem. A raven apparently engaged in horseplay - sliding down snowbanks, buzzing deer - may have a functional motive: scraping off parasites, or finding food. But surely no species other than our own can possess such premeditation? Such deceit? Such in-your-eye sassiness? Corvids can't be as smart as they seem...except they are. Scientist or lay person, everyone who watches ravens realizes that these birds seem brilliant because they are brilliant. They're feathered Einsteins.
There's another reason for the tardiness of science in the area of corvid intelligence. The observations that support raven braininess are mostly anecdotes - that is, one-of-a-kind stories. And for three hundred years, science has treated anecdotes as optional illustrations, mere flourishes. A really sound paper is based on reproducible statistics; anecdotes by themselves are nothing more than icing on the scientific cake.
Increasingly, however, scientists are basing papers on unique observations, without parallel control situations and with more than the usual lone independent variable. Well-chosen anecdotes may now comprise a paper's main content, and be its main theoretical vehicle. The change extends to disciplines other than ethology. When elegant equations in hydraulics have proven insufficient to restore a river system, geotechnical engineers have found the facts they need in the tales of old-timers who grew up along the river banks. Science is realizing there's a place for anecdotes.
That's certainly true in corvid research. When researchers present ravens with situations the birds have never encountered, the birds usually assess the circumstance and solve it before the scientists' eyes. Ravens have deduced how to transport two doughnuts to a food cache in one trip:
Reach through one doughnut hole, grasp other doughnut; (or)
Balance first doughnut on top of second.
Orthodox ethology struggles in vain to reduce such anecdotes to footnotes by overwhelming them with observational statistics. ["10:03:30 AM. Three Corvus corax visit wolf kill, stay 11 min 22 sec. Made four flights, presumably caching food. Lacking banding, birds may not be identical. 10:16:05 AM, no activity"]. The ethologists' conversion to raven storytellers is amusing to human bird-watcher-watchers; it must make corvids roll on the floor with mirth. The anecdotes dominate - the corvids insist on it.
The scientist who has done more than any other to study the raven is Dr Bernd Heinrich, of the University of Vermont. Despite years spent observing corvids both captive and in the field, Dr Heinrich often resorts to anecdote to explain his birds' behavior. In 1998 he designed an anecdotal experiment to demonstrate that ravens really were intelligent: specifically, that they could devise new behavior to solve a problem they had never before encountered.
Dr Heinrich suspended a choice tidbit of dried salami from a branch by a 75-cm string. The string was strong and the food was dense and well above the ground: hence no raven could hop up to it or seize it in a flyby. To get the food, a raven would have to deduce six steps ab initio, then perform them in sequence:
Perch on the branch above the string
Reach down and grasp the string in its beak
Pull one loop of the string up and over the perch
Lift one foot and step on the loop to prevent string slippage
Shift the bill-grip to the hanging portion of the string
Repeat the above steps until the whole string was taken up
As the scientist expected, ravens feeding at an animal carcass in the wild were startled by the hanging food and gave it a wide berth. Ravens raised by Dr Heinrich in an aviary inspected the setup, tried and failed to rip off the bait, and seemed to lose interest. But just as Dr Heinrich was concluding that no bird could exhibit intentional behavior, a lone raven flew down to the branch, perched above the string, and performed the entire sequence perfectly in front of the dumbfounded scientist on the first try.
"I conclude," writes Dr Heinrich in Mind of the Raven, "that [the ravens] experience some level of consciousness, and use it for insights to make decisions." (Incidentally, when Dr Heinrich submitted these ground-breaking observations to scientific journals, there were rejected five times - presumably as too anecdotal.)
The real reason why ravens fascinate us may be a hunting partnership that goes back to the Old Stone Age. Dr Heinrich has propounded a new theory, supported by anecdotal and statistical observations. Over millions of years, he thinks, corvids developed a symbiotic link with large mammalian pack-hunters. The birds learned to act as aerial observers, spotting prey and revealing it to the hunter species; the birds then shared the kill. At first this honcho hunter was Canis lupus, the wolf. But when a more effective hunter emerged, the ravens' high intelligence let them transfer their attachment. That upstart was H.sapiens sapiens - us.
Dr Heinrich cites a striking anecdote to support his theory. In 1998, a woman in Colorado noticed the wild activity of a raven directly over her head. Disturbed by this, she glanced around - and looked directly into the face of a cougar about to spring on her. Being religious, she believes Heaven sent the bird to warn her. Being a corvid ethologist, Dr Heinrich believes the raven led a symbiotic predator to an easy kill in order to share the meat.
Dr Peter Sherrington, an avian ethologist who lives east of the Rockies on the high plains of Alberta, agrees with Dr Heinrich's thesis "without question...I often see a crowd of ravens out on the plain, following wolf packs. I have observed a pack of twelve wolves accompanying an overhead armada of ravens and magpies. In this area, ravens are even shifting their attention to coyotes."
Such research goes far to explaining why corvids inspire love and hate in humanity in equal quantities. Hunting cultures revere ravens; farming cultures are more likely to find them pests. In this, the PR profile of corvids may parallel that of their allies the wolves. Throughout prehistory, awe and reverence; then, from the Neolithic Revolution, millennia of hostility; then back to reverence in a few short years. Dr Heinrich calls ravens "wolf-birds." In how we view them, they may be exactly like the wolf.
Whatever the attitude toward corvid species, there's little chance that the genus will be endangered. What's happened in Alberta, Germany and Chatham doesn't worry the experts at all.
"I don't think Corvus corax is threatened by this latest Act revision," says Gordon Court, an Alberta wildlife biologist. "I've seen only one piece of land where anyone actually shot a raven. They're pretty darned hard to hit."
Adds Dr Sherrington: "Magpies were persecuted for years in Alberta, with no real effect on their population numbers. They're corvids, after all. Most corvids are simply too smart to get hurt."
Or too smart to starve. In Alberta in January 2020 several ravens were observed tormenting 10kg Western hares – pecking and buzzing them – till the hares, driven to distraction, fled into road traffic and became roadkill. At that point the ravens dined on them. The parallel with Plains Indigenous peoples driving bison over cliffs seems too obvious to state.