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How a 5-Ounce Bird Stores 10,000 Maps in Its Head

It weighs only four or five ounces, its brain practically nothing, and yet, oh my God, what this little bird can do. It’s astonishing.

Photograph by Diana Tomback
Photograph by Diana Tomback

Around now, as we begin December, the Clark’s nutcracker has, conservatively, 5,000 (and up to 20,000) treasure maps in its head. They’re accurate, detailed, and instantly retrievable.

A Clark's nutcracker with a thought bubble full of maps
Photograph by Glenn Bartley, Alamy; Maps courtesy of jaffne, Flickr; GIF by Becky Harlan

It’s been burying seeds since August. It’s hidden so many (one study says almost 100,000 seeds) in the forest, meadows, and tree nooks that it can now fly up, look down, and see little x’s marking those spots—here, here, not there, but here—and do this for maybe a couple of miles around. It will remember these x’s for the next nine months.

How does it do it?

32 Seeds a Minute

It starts in high summer, when whitebark pine trees produce seeds in their cones—ripe for plucking. Nutcrackers dash from tree to tree, inspect, and, with their sharp beaks, tear into the cones, pulling seeds out one by one. They work fast. One study clocked a nutcracker harvesting “32 seeds per minute.”

These seeds are not for eating. They’re for hiding. Like a squirrel or chipmunk, the nutcracker clumps them into pouches located, in the bird’s case, under the tongue. It’s very expandable …

Drawing of one clark's nutcracker bird without seeds in its cheeks, and another clark's nutcracker with its cheeks full of seeds
Drawing by Robert Krulwich

The pouch “can hold an average of 92.7 plus or minus 8.9 seeds,” wrote Stephen Vander Wall and Russell Balda. Biologist Diana Tomback thinks it’s less, but one time she saw a (bigger than usual) nutcracker haul 150 seeds in its mouth. “He was a champ,” she told me.

Next, they land. Sometimes they peck little holes in the topsoil or under the leaf litter. Sometimes they leave seeds in nooks high up on trees. Most deposits have two or three seeds, so that by the time November comes around, a single bird has created 5,000 to 20,000 hiding places. They don’t stop until it gets too cold. “They are cache-aholics,” says Tomback.

When December comes—like right around now—the trees go bare and it’s time to switch from hide to seek mode. Nobody knows exactly how the birds manage this, but the best guess is that when a nutcracker digs its hole, it will notice two or three permanent objects at the site: an irregular rock, a bush, a tree stump. The objects, or markers, will be at different angles from the hiding place.

a drawing of clark's nutcracker looking at a tree stump and a mountain in the spring, with arrows pointing between the bird, the mountain, and the stump
Drawing by Robert Krulwich

Next, they measure. This seed cache, they note, “is a certain distance from object one, a certain distance from object two, a certain distance from object three,” says Tomback. “What they’re doing is triangulating. They’re kind of taking a photograph with their minds to find these objects” using reference points.

Psychologist Alan Kamil has a different view. He thinks the birds note the landmarks and remember not so much the distances, but the angles—where one object is in relation to the others. (“The tree stump’s 80 degrees south of the rock.”) These nutcrackers are doing geometry more than measuring.

a drawing of clark's nutcracker looking at a tree stump and a mountain in the rain, with arrows pointing between the bird, the mountain, and the stump
Drawing by Robert Krulwich

However they do it, when the snow falls and it’s time to eat, they’ll land at a site. “They will perch on a tree,” says Tomback, “on a low branch, [then light onto the ground, where] they pause, look around a bit, and they start digging, and in a few cases I’ll see them move slightly to the right or to the left and then come up again.”

She’s convinced that they’re remembering markers from summer or fall and using them to point to the X spot—and, “Lo and behold, these birds come up with their cracked seeds,” she says. “And it’s really pretty astounding.”

In the 1970s, Stephen Vander Wall ran a tricky little experiment. He shifted the markers at certain sites, so that instead of pointing to where the seeds actually were, they now pointed to where the seeds were not. Like this …

Picture of a clark's nutcracker standing between two X's and looking confused
Drawing by Robert Krulwich

And the birds, as you’d expect if they were triangulating, went to the wrong place.

But at sites where he left the markers untouched, the birds got it right. That’s a clue that each of these birds has thousands of marker-specific snapshots in their heads that they use for months and months. When the spring comes and the birds have their babies, they continue to visit old sites to gather seeds until their chicks fledge.

The mystery here, the deep mystery, is how do they manage to store so much data in their heads? I couldn’t possibly do what they do (I can’t even remember all ten digits in a phone number, so I’d be one very dead nutcracker in no time). Is their brain organized in some unique way?

Is their brain plastic? Can it grow more neurons or more connections when it needs to? Chickadees are also food hiders, and they do grow bushier brains when they need to, expanding in the “remember this” season and contracting afterward. Do Clark’s nutcrackers do that? We don’t know.

Whatever it is they do, I want what they’ve got.

41 thoughts on “How a 5-Ounce Bird Stores 10,000 Maps in Its Head

  1. I wonder whether they might have a few locating rules, that, given the rock and the stump and the whatever, always bury it exactly here. When later presented with the general spot, the rules give the exact location.

    Now they just need remember those general places, and the rules.

    -kb

    1. What is even more remarkable, on top of remembering all the locations, is remembering with seeds need to be eaten first and which seeds can remain fresh for a while. A corvids mind is absolutely a powerhouse, considering how small it is.

    2. But if they were remembering general rules, wouldn’t the hiding spots be rather vulnerable to raiding by other birds?

  2. Robert, you continue to amaze and inform me at the same time with your wonderful explanations about the way things (almost anything) works. It started when I was your intern at the National Press Building in DC in 1975. Keep up the great work you do. All of the best, David

    1. David! Wow, what an unexpected pleasure. I put these things out there, not sure who is going to find them, not at all confident anyone will notice, and along you come, you who I haven’t seen since the 1970’s, (even though I have an old WBAI “folio”, with you prominently on the cover page working, razor in hand, over a tape recorder). I guess this is an oddly public place to have a reunion, but thank you so much for writing, and for your thoughts. I remember those days very fondly.

    2. David – i seem to be posting as Becky, my wonderful editor, (but that’s only because the mysteries of National Geographic’s website continue to bedevil me.)

  3. The birds likely employ a form of avian subconsciousness being tapped into, not unlike how a stage hypnotist can enable an ordinary subject to recall thousands of numbers sequentially.

  4. I thought I was re-routed to NatGeo Kids site.:) This is an awesome article. These birds certainly are very familiar to the place, as they fly around everyday. Their memory is astonishing, indeed. However, I wonder if they also get those seeds that were stored/kept by other birds come harvest time. #finderskeepers

  5. The God of heaven created a perfectly beautiful bird and a planet in a universe that is so vast it is unimaginable. This same God created man for His glory and to live forever and ever with Him.

    1. Amen. This just one of many examples of complex marvels in Nature, another being the process of metamorphosis, that fairly shout an intelligence far greater than ours is involved in all of this.

        1. Just because we don’t understand it doesn’t mean God did it and if we do understand it, it doesn’t mean God didn’t. But the discredited oxymoron of intelligent design?

    2. I was disappointed by your comment. I thought this was a scientific website, for the enquiring mind. So, why bring God into it? Why this attitude of “wow, this is amazing, so God must be amazing, and this is what He has done”? God might be amazing, but what we need here are rational answers. Not glib explanations that help no one.

  6. They must be using some general rules for hiding (it’s like putting milk into the fridge, even that there are millions of houses If I go looking for milk in doesn’t matter what house in the world, most likely I will find milk in the fridge and it doesn’t matter how bad my memory is as long as I remember that milk is in the fridge) also since they hide in so many places they only need one of two general things to remember (marks) something common in their environment e.g stump, rock, building… Also it’s not a fact that they manage to find absolutely all their hiding spots, because they may not need this much as well as they just may not find, because it was picked up by other bird. However, using common places they can find nuts that were hidden by other birds. Since they use thousands of hiding places, they absolutely should have no problem finding it wherever they go as long as other nutcrackers live there.

    1. Jaroslavas — I don’t think this explanation works. These birds aren’t storing seeds, they’re hiding seeds. They know that not only will other birds steal what they’ve hidden, so will field mice, squirrels and rodents of all sorts. So it’s NOT like putting something in the obvious place, like putting milk in the refridgerator. I think it’s more like stashing seeds in an UN-obvious place, like putting milk in the coldest part of your hall closet.

  7. As a memory athlete, this is wonderful to read. I and my fellow competitors train our minds and constantly push the limits of what we can remember. Because of its memory ability, I think the Clark’s nutcracker has just become my new favorite animal (over the elephant)! Thanks for this interesting article. I’m going to mention it in the seminars and keynote speeches I do to help people remember better.

    1. Brad, is it possible the birds revisit the same route (or have a rule to generate the route). Then they would have another rule to choose a place to stop, and a third set of rules for places they choose to hide at, once they are at a stop on the route?

  8. Perhaps what the nutcrackers are cuing into is their own mental ‘left over’ in their brains from the last time they were at the seed site. Their own mental ‘ magnetic imprint of the seed area, and when hungry in winter they bring up , in memory, the closest mental’ left over’ imprint of the seed area and fly to that site. Like when one is deeply interested in a TV program and then have to interrupt and go off for a few minutes, when one returns to the sofa one experiences an immediate reconnection to the TV and what was going on prior, reentering one’s mental ‘left over’.

  9. I have a Lowrance model 100 GPS that stores 750 waypoints on it at my discretion plus it has all the cities in the USA and some from Mexico! But, my seeds I distribute on the internet instead of cracks in the trees.

  10. Whether they are capturing an image associated with an angle from the other marker.. I’m fascinated that this low frequency sensor bearing animal might be compelled to continue caching, precisely because some seeds will be lost and propagate the trees! How do the birds find their hiding places? I’ll bet it has something to do with the empty spaces where there are no trees! or no big branches! These vulnerable open spots are perfect for the birds to store their food and some of the ‘bycatch’ grows new trees. Dare we speculate that the birds have fathomed a connection between the seed and the tree? Could they be planting trees? Could the trees be ‘harvesting’ the bird-power in a deliberate effort to expand their reach? Some say it’s all just the dance of reality.

  11. Wow! What a great article! I can’t wait to share this with my Natural Resources students. We are doing map reading, GPS, and Geocaching right now. It also ties so well with wildlife study. Thanks!!

  12. The nutcracker’s brain mapping could may be a rich source of clues to understand the brain especially in children diagnosed with dyslexia. Thank you so much for your article.

  13. Has anyone considered that they, using the landmarks, store one road-map in their heads and hide the seeds in what would be obvious locations along the route?

  14. Keep on connecting the size of brain with its usability, and you’ll create all sorts of mystery. I could probably write a long story on dragonfly behavior with facts and photos you wouldn’t believe… the way it relates to someone who saves it from water, how it comes back and lands upon an offered hand… how it will chase away some other dragonflies if they get too close… how it comes back and spends a whole afternoon with us the way we do with our friends… and how those we helped in some way will immediately climb to your finger, while the others won’t let you come closer than half a meter…

    And yet, the whole dragonfly weighs just a few grams, and has a brain size hardly worth speaking of!

    Sooner or later you’ll start to connect such behavior with intelligence, soul, and more of the qualities the science still feels uneasy to speak about. You’ll think about the living being’s energy or “astral” body where all senses reside (and who knows what else)… and you will not be so ready to look for data within the hardware! Rather, you’d perhaps be more inclined to recognize the binary value of life, where what we see isn’t all there is.

    As to the bird… How many gigabytes of maps and software can be stored in some dumb GPS unit memory, and revoked by hardly some tens of satellite signals? And why would such device have the ability to access more data than some living being?

    We can’t discern everything from mere observation of some living being’s behavior, nor can we find anything revolutionary by dissecting some brains, big or small! There is a theory that brains are just “EMF”-generating units, and all data related to some section or other is stored “in the cloud” or in the generated field.

    Finally, consider the fact that a dying person loses several grams of body weight at the time of exitus (which is not called thus for nothing, btw) – and from that moment you can’t speak of “person” any longer: there is the bodily remains, and there is the most important part that has left it.

    Does this not point to some other direction in our explorations? Sure does. But “official” science still looks for Life in cadavers, like 200 years ago, trying to ignore what some ancient science has known thousands of years ago.

    1. Fascinating comment: I was concerned at why the original author’s piece neede a “…oh my God, ” profanity in the heading when the theory was enough for most of us!

  15. I am amazed by how the bird can cram so much data in its head. Also, was there an experiment about changing the distances between the markers and the seeds and see how that would affect how the bird found the seeds? I would be very interested in that study.

  16. My Grandmother sent me this article as I just recently explained an assignment I wrote at university on cognition in African Elephants and Pigeons! Its a really interesting article and some really good ideas on how they triangulate.

    Uncovering the ‘How’ is the tricky bit! Comparative cognition and intelligence is being well researched by Behaviourists and gives some interesting ideas. In my assignment I found that research indicates that its not just how big the animals’ brain is, but the specialization of certain structures- for instance Pigeons have a navigational map based on atmospheric odours due to the presence of the Piriform cortex.
    You also mentioned Neurons. Elephants have more neurons altogether in their brain than Humans but less than Chimps, yet when comparing the Elephant and Human cerebral cortext the Elephant has 1/3 the amount of neurons in this area of the brain that Humans do. So perhaps its not just how many neurons, but where are they most dense in particular brain structures.

    Comparative cognition is a fascinating subject, and the more you look into it the more you realise just how intelligent seemingly stupid animals (such as Pigeons) actually are!

  17. I thoroughly enjoyed this article. . . . and it seemed to me that all birds possess equally (perhaps different faculties and qualities) .. . .and cruel humans cage them, shoot them, eat them for their own perverse purposes. . . . I must say I drew great pleasure from reading the comments from intelligent, articulate and compassionate people. . . .

  18. I think all birds can map. We have Canada geese living in the city who can find the same building to nest at year after year and it’s right downtown nowhere near any of their regular pond hang outs. It’s actually the Law Bldg and they always nest there on a balcony.

    They also know how to walk through the city to get their goslings to water up to a mile or more even though the rest of the time they are flying over the city. Bird brains aren’t so dumb.

  19. I read recently that a discovery was made that a birds brain is compressed and that there are 2-4 time more brain cells that was believed. Kind of a brain version of a zip file.
    Maybe being a bird brain isn’t so bad.

  20. What we can easily store in a fingernail-size mini-SD card today we couldn’t put into the memory of a computer the size of an enormous building half a century ago. The WAY nutcrackers store information in their tiny brains may just be completely different from that of animals whose brains are hundreds of times bigger than theirs.

    That’s the miracle of Nature.

  21. Why do we think this bird is a genius? Yes it’is but i want to explain why this bird is not so smart as we think.

    This bird can remember 20,000 places and up to 3 to 5 marks each spot.
    We can count to one million if we want. We can remember 1000 websites. We know how to build things like houses we can make computers and laptops. We can do even more.

    A bird only have to remember the spots. And how to built a nest, fly and care for it’s chicks. The last thing is what whe all have care for kits, babies and other humans.
    We can remember much more things.

    And do you realy want to rememer 20.000 spots? maybe we do that already like, house->bedroom->bed. How do we now it’s a bed? Simple: It’s soft, has 4 poles to stand on and you can you can lie on it. The bed is the spot and the the characteristics are the marks. And how do you know to go to work? street one-> go to the left -> street 2. How do we know it’s a other street? Simple: that one tree, the houses, the marks on the road and go on… And if we don’t know the route to work. We read signs, we can remember more that one million words.

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