Brain Birds: Amazing Crows and Ravens

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Of course, the raven rapping at Poe’s chamber door also displayed another corvid vocal skill, that of mimicry (or, in Edgar Allan’s words, quothing: “Nevermore!”). Crows and ravens can indeed mimic human speech, as well as a host of other sounds. Ravens, especially, are masterful imitators of their aural surroundings; sources cite realistic raven renditions of bubbling brooks, creaking branches, barking dogs, revving engines and dynamite explosions.

But it’s brainpower, not bravado vocals, that really sets crows and ravens apart from other animals. They have the largest cerebral hemispheres, relative to body size, of any birds — the raven’s brain is the same size in relation to its body as a chimpanzee’s. More significantly, crows and ravens apply their brainpower; they learn quickly, solve problems and store knowledge in long-term memories.

Furthermore, crows and ravens understand cause and effect. In the South Pacific, New Caledonian crows sculpt twigs into hooked probes that they use to pry out otherwise inaccessible grubs — they make their own “crowbars.” The same crows nip the edges of rigid leaves to create sawlike teeth, then shove the barbed tools beneath leaf litter to spear prey. They also carry their tools with them on foraging expeditions, and store them for later use.

Stories abound of crows or ravens dropping nuts or clam shells onto highways and other hard surfaces to break them open. In Japan, crows are reported to have taken the strategy a step further by placing nuts in front of the tires of cars stopped at red lights. Some claim to have seen ravens chasing squirrels and rabbits into the paths of oncoming cars, creating premeditated roadkill. Biologists say that ravens follow the tracks and howls of wolf packs, as well as the sounds of hunters’ gunshots, to locate the spoils of their kills.

Scientific research confirms much of the anecdotal evidence. In one study of captive birds, scientist Bernd Heinrich dangled a bit of meat from the end of a 2-foot-long string tied to a perch. He then watched his test subjects — first a pair of American crows, and later five common ravens — attempt to bring home the bacon (in this case, it was actually salami). The crows tried flying at the food, then tugged at the string a few times, but gave up within 15 minutes. Time to study the situation didn’t help; after 30 days, they still hadn’t solved the problem. The ravens spent a few hours glancing at the puzzle, as if weighing the possibilities. Then one bird flew to the perch, hoisted a length of string up with its beak, stepped on the loop, pulled up another length, stepped on that loop, and so on until it had reeled in the food. Ultimately, three more ravens also solved the problem. Two improved on the technique by simply grabbing the string and side-stepping along the perch.

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