Corvid savants

February 2, 2011 • 7:54 am

The science section of yesterday’s New York Times has a piece about New Caledonian crows (Corvus moneduloides) by the ever-readable Natalie Angier.   She highlights their remarkable intelligence, manifested in their ability to make tools:

In the complexity, fluidity and sophistication of their tool use, their ability to manipulate and bird-handle sticks, leaves, wires, strings and any other natural or artificial object they can find into the perfect device for fishing out food, or fishing out second-, third- or higher-order tools, the crows have no peers in the nonhuman vivarium, and that includes such textbook dexterous smarties as elephants, macaques and chimpanzees.

Videos of laboratory studies with the crows have gone viral, showing the birds doing things that look practically faked. In one famous example from Oxford University, a female named Betty methodically bends a straight piece of wire against the outside of a plastic cylinder to form the shape of a hook, which she then inserts into the plastic cylinder to extract a handled plug from the bottom as deftly as one might pull a stopper from a drain. Talking-cat videos just don’t stand a chance. [JAC note: I object to this last sentence.  Angier probably hasn’t seen Maru jump into a box.]

These crows are the only animals known to make tools from stuff they haven’t previously encountered in nature.  Here’s crow Betty extracting a plug from a tube. At about 22 seconds she realizes that she isn’t going to get the object with a straight wire, and bends it into a hook around the tube.  Amazing!

Why are these crows the most adept tool-makers of all animals besides humans—and that includes other primates?  Angier highlights two new papers explaining the theories (I confess that I haven’t read ’em yet).  These include an enlarged brain (typical of corvids), a beak seemingly adapted to manipulate natural objects, and a social system with a long enforced “childhood” (juveniles stay with the parents for up to two years), promoting the acquisition of tool use by learning from parents and siblings.

The juveniles need their extended apprenticeship. “They’re incredibly persistent, wildly ripping and hacking at Pandanus leaves, trying to make it work,” said Dr. Holzhaider, “but for six months or so, juveniles are no way able to make a tool.”

The parents step into the breach, offering the trainee food they have secured with their own finely honed tools. “By seeing their parents get a slug out of a tree, they learn that there’s something down there worth searching for,” she said. “That keeps them going.”

They even have local toolmaking “styles”:

The birds are indefatigable toolmakers out in the field. They find just the right twigs, crack them free of the branch, and then twist the twig ends into needle-sharp hooks. They tear strips from the saw-toothed borders of Pandanus leaves, and then shape the strips into elegant barbed spears.

With their hooks and their spears they extract slugs, insects and other invertebrates from deep crevices in the ground or in trees. The birds are followers of local custom.

Through an arduous transisland survey of patterns left behind in Pandanus leaves by the edge-stripping crows, Gavin Hunt of the University of Auckland determined that toolmaking styles varied from spot to spot, and those styles remained stable over time. In sum, New Caledonian crows have their version of culture.

Corvids are amazing birds (the family Corvidae includes crows, rooks, ravens, jays, and magpies).  If you want to read more about their smarts and skills, by all means get a copy of Bernd Heinrich’s Ravens in Winter, describing his experimental and observational studies of ravens (in the same genus, Corvus, as crows) at his New England cabin in winter.  It’s a great book for biology-lovers.

Here’s a cool seven-minute video showing the intelligence of these birds when faced with a perplexing laboratory situation.  They seem to be able to understand concepts, and transfer that understanding to novel situations.  Even nonhuman apes can’t do what these crows do!

And I can’t resist adding this David Attenborough video of Japanese crows dropping nuts on the street to crack them, using the cars to do the job.  He claims (and this is unbelievable) that the crows actually drop the nuts at pedestrian crossings, so that they can retrieve the cracked nuts when the light turns red! (Just click on the “Watch on YouTube” line.)

Want more videos showing corvid smarts?  Here’s a great one from the BBC.

52 thoughts on “Corvid savants

  1. I for one welcome our new corvid overlords…

    Clearly Odin’s ravens, Hugin and Munin (Thought and Memory) continue to watch over their flock.

  2. I can highly recommend “Mind of the Raven: Investigations and Adventures with Wolf-Birds” by Bernd Heinrich, ISBN 0060930632.

    A fascinating account by a professor emeritus in the biology department at the University of Vermont of his encounters with the local raven population.

    As an avid runner I can upon this author through his book “Why We Run: A Natural History”.

    Heinrich is even crazier than I am, he is one of those ultra marathoners that considers any race less than 100 km for the weak (perhaps literally) of heart.

    1. One time Heinrich came to UCLA to give a talk and he insisted on running from LAX to Westwood (which is probably less than 15 miles, but still).

  3. I’ve been a corvid fan since I started birdwatching. They are amazing animals.

    They sometimes wreak havoc in a garden, though, apparently just out of curiosity. Our magpies often take up the labels we use for garden plants, so we lose track of what variety is planted where.

  4. One “strong” argument I’ve heard in favor o the existence of a non-material human soul is “innovation”: how can a jumble of atoms an molecules called the human body come up with new solutions for a problem, one it has never encountered before?
    I wonder if crows go to heaven or hell.

    1. oh god… I have to pass this on to my SO, who studied with the late Ev Rogers as he was compiling “Diffusion of Innovations”. I’d love to see this in print somewhere.

  5. I’ve heard that ravens are even smarter than crows surpassing even dogs in intelligence. The best demonstration was a Youtube video of a raven that caught a fish using an unattended fishing pole left by an ice fisherman. It saw the pole bend with a hooked fish (inductive reasoning) and used its beak and foot to pull the line up and land the fish. This was apparently a wild bird that only learned by observing humans fishing.

    1. I couldn’t find that YouTube video post link if you have it), but here’s one of a crow using food as bait to catch fish.


    2. So far, the New Caledonians seem to be at the top of not only the corvid family, but at the top of all avians. And they surpass even chimpanzees at certain kinds of reasoning, at the least. H. sapiens might well be the only species with superior problem-solving skills.

      I’d pick corvids as the type of life most likely to develop a technological civilization if humans go extinct (assuming we don’t take out the corvids along with us, of course). The New Caledonians are probably only several million years behind us, and on a very similar trajectory.



    3. Once I gave a hot french fry to a hooded crow. The crow gobbled it, but then spat it out — too hot! — and then carried it to a nearby puddle, dipped it in to cool it, and then swallowed it.

      Obviously it didn’t learn that from humans — it must have figured out that “water cools food” on its own.

  6. What I would be curious to see is if, given the wire hook situation, but with nothing to bend it on, they could use the straight wire to retrieve an object they could then use to bend the wire. So we know that they can use tools, and we know that they can use sequences of tools, and we know they can make tools, the question is now can they use tools to make new tools.

    Recovering an object needed to modify another object implies they understand the other object to be a tool needed to make a new tool.

    1. In one of the related videos linked at the end of the above video posted by JAC, Betty the crow is shown selecting a tool to retrieve a longer tool to retrieve a longer tool to retrieve the food.

      Not quite tools to make tools, but tools to acquire tools, at least. And she gets it right away, pulling the tools in order.

      I like corvids. I’m always trying to take pictures of the local magpies and ravens, but they get instantly suspiscious of me as soon as I pull out my camera or stop my car. I have many blurry, poorly-composed pictures of corvid tails.

  7. This is a great video on by a guy named Joshua Klein on the intelligence of crows. He provides many more examples of what these birds are capable of.

    1. Dang! You beat me to it! That’s what I get for taking a walk… It *is* a great TED talk, though (he also shows the bending-a-wire video and nuts-in-traffic video) and I think he brings up important points about species that are thriving amongst humans and how we should strive to find balance with them (rather than exterminating them).

      Here’s the link!

  8. I swear that the corvids laugh at me whenever I walk through their territory. I’ve always wondered what they find so funny. In the last place I lived at, one of them even acted like a cat – he’d nag me to mow the lawn so he can get an easy meal.

    1. On the Japanese nature programme ‘Darwin’ some time ago, there was footage of a goshawk (I think) taking out crows just above a river so that they could be drowned in precisely that way; and the goshawk trained its young to do the same (well, they learned by watching and then by trial and error). No, it’s not very nice, is it?

      1. Oh–we watch that show, too! It’s one of my kids’ favorites (well, and mine, too:-)) I haven’t been able to find it available for viewing on YT or elsewhere on the web, though. Zan nen!

    2. Fascinating. I had not heard of this behavior. Predation may not be “nice” but it is necessary. Corvids eat plenty of baby birds…

      1. I know: I saved a young owl from a crow in the wood at our local shrine, spent a sleepless night feeding at short and regular intervals with chewed chicken, and then took it to the Tama Zoo, where after scolding me for interfering in ‘natural processes’ they took it to look after…
        In fact, I love crows because of their often roguish intelligence. And I love hawks because of their beauty. And owls…

  9. Their facial-recognition ability (not to mention hounding and spreading the word about anyone who they think is a “bad guy”) is also pretty cool. NPR Radio Story on crow facial-recognition (the “Listen to the Story” link at the top).

  10. Thank you Jerry

    The NYT article: Angier has a deft & witty style. I like the little nuggets of anthropomorphism she drops in here & there such as at the end of this paragraph ~ so like married life…

    “Being cultured is hard work. In studying the birds’ social life, Dr. Holzhaider and her colleagues confirmed previous observations that New Caledonian crows are not group-living social butterflies, as many crows and ravens are, but instead adhere to a nuclear family arrangement. Males and females pair up and stay together year-round, reaffirming their bond with charming gestures like feeding and grooming each other, sitting close enough to touch, and not even minding when their partner plays with their tools”


  11. A friend told me he saw a crow chase a squirrel into the path of an oncoming car, and then ate the resulting roadkill. Now there’s some enterprising tool use.

    I second the recommendation of the Heinrich books. He’s a great writer and the topic is fascinating.

    1. According to Heinrich, ravens direct prey to the local top predator (typically wolves, but there have been anecdotal reports of ravens directing human hikers towards mountain lions) and then feeding from the kill.

      A large part of raven childhood consists of habitualizing the wolves to the presence of the ravens.

  12. Every day I see opposably-thumbed primates with PhDs who can’t get cherry tomatoes into a salad bowl despite the proximity of several appropriate tools. More physically intelligent conspecifics have to use yet more tools to clean them off the floor.

  13. Here’s a 2 1/2 year old NYT article on face recognition in UW Seattle crows.

    Last summer, our cat (Butter) somehow managed to catch a bird — luckily a common house wren, quickly dispatched on our front stoop. I separated cat and ex-wren and was cleaning up when I got that chilly feeling that I was being watched. I looked up to the nearby street light, and on the electric wire maybe 30 feet from me was about 15 house wrens, all facing me, silent and motionless. It’s the only time I ever noticed any birds hanging out on that wire, let alone 15 solemn house wrens – no warnings, no screeches, nothing.

    I’d heard of bird funerals, but never witnessed one before.

    1. I’ve experienced something similar with the Blue Jays. One of their flock of six was laying dead on a mound of snow across the street just a few days ago which was, of course, attracting a lot of attention from the magpies in the area. The remaining 5 jays have devoted a large part of the last few days keeping the scavengers away from their deceased flock mate and at times seemingly mourning over it from the branches of the nearest tree with pitiful little sounds very much unlike the usual jay array of calls. I guess the wee wrens feel a similar sense of loss — very interesting. Or perhaps they were plotting against your cat 🙂

  14. I saw one video of a raven opening a digital safe one time (think it was on NOVA). Can’t find it on YouTube, unfortunately.

  15. Loved the article and all the vids–thanks, all.

    Listening for crow alerts has resulted in many of my best hawk sightings, among other things. Was happy to see a couple of the resident crows out foraging after the blizzard today…

  16. Whenever I ride in the indoor arena at our riding facility I’m accompanied by a KLONK-klick-cklick-klick-klick sound. I wondered for years what the heck it was, until I one day saw several magpies and a crow pick up nuts from under trees, fly up to the riding arena metal roof, and then as violently as possible throw the nut down on the roof. The nut would then roll down the metal roof, fall to ground with a thud – usually slightly crushed, enough for the bird to get inside and nom the nut. I’ve seen jackdaws do the same on this roof, so apparently the different birds – magpies, jackdaws and crows – all learn this nut-cracking behaviour.

  17. I have a one-person hunting blind I use for bird watching; last autumn I inadvertantly set it up under a white oak with a bumper crop of acorns. All day long the squirrels & bluejays were busy harvesting. The jays would often take their acorn to a nearby tree limb, hold it with their feet, and peck away until, I guess, they reached the nutmeat. While not a notably special behavior, I am still always amazed at what birds can do with just feet and beak. Though jays, especially in groups, are usually quite raucous, these harvesters were as silent as can be (except for the acorn pecking, which sounded just like a woodpecker).

    Another cool member of this family, the Clark’s Nutcracker of the mountain west, is thought to be instrumental in keeping oaks on hills. 😀 The idea is that round hard seeds like acorns would tend to bounce downhill, if anything, and the birds manage to carry a few of them upslope instead. (One imagines there might be other acorn-loving vectors as well…) The vision of oaks otherwise essentially sliding off the hills over time is amusing..

  18. I’ve not had the pleasure of witnessing tool use amongst the crows who use my backyard and bird bath as a drop-in day care facility for their fledglings, other than perhaps using the hard surface of the bath to hammer morsels of food into smaller bits for passing around to their incessantly hungry family, however I did have the distinct pleasure of hearing one of my crows say “hello” to me one day while out tending to my garden. I have for years said “hello crow” when they’re in the yard, never thinking one day I’d hear it back. My family think I’m mad, but later the same summer the same crow said “hello” again. And although it’s unlikely the crow realizes that it is a greeting (or maybe they do), it warms my heart to hear it. I’m currently training the jays and magpies — I’ll keep you posted 🙂

    1. Whaddaya know, I’m not the only one who talks to “my” crows!

      I’ve yet to get a reply, but a month or so ago I spent several minutes watching and listening to one crow practice a couple of very un-crowlike vocalizations. The first was a very accurate rendition of a woodpecker pecking, and the second sounded something like a dove. I’m abysmal at bird calls & woodpecker cadences, but I’m quite sure a better birder would have been able to ID the species this crow was mimicking.

      Fantastic birds!

      1. They are indeed. I love watching them. Now if I could just figure out a way to get paid for it…:-)

    2. Excellent book, which has probably been referenced before, is Mind of the Raven. Ravens have been observed to mimic many sounds including human speech and in one case, an explosion.

      1. I actually have that book sitting on my bedside table. I truly am looking forward to doing more than leafing through it but first must finish a book series I’m reading which, funny thing, is filled with ravens and crows doing incredible things like delivering messages (like pigeons) and mimicking words (“A Song of Fire and Ice” series by George R.R. Martin upon which the HBO series ‘A Game of Thrones’ is based upon). All fiction and fantasy of course but keeps my fascination with the Corvids satiated 🙂

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