True Facts: Crows That Hunt With Sticks

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Featuring the work of:
Dr Natalie Uomini, Max Planck Institute
Dr Anne B. Clark, SUNY Binghamton
Dr Michael Griesser, University of Konstanz
Dr Kaeli Swift, University of Washington
Dr Alex Kacelnik, University of Oxford
Dr Jolyon Troscianko, University of Exeter
Dr Christian Rutz, University of St Andrews
Dr Diana Liao, University of Tübingen
Dr Gavin Hunt, University of Auckland
Dr Nicola Clayton, University of Cambridge
Dr Sonja Hillemacher, University of Bonn
Zita Fülöp
Neil Smith

Citations:

Asakawa-Haas K, et al. Partner Choice in Raven (Corvus corax) Cooperation. doi: 10.1371/journal.pone.0156962.

Bayern, A.M.P.v. et al. Compound tool construction by New Caledonian crows. https://doi.org/10.1038/s41598-018-33458-z

Chappell, J et al. (2004). Selection of tool diameter by New Caledonian crows Corvus moneduloides. 10.1007/s10071-003-0202-y.

Düring DN et al. The songbird syrinx morphome: a three-dimensional, high-resolution, interactive morphological map of the zebra finch vocal organ. doi: 10.1186/1741-7007-11-1.

Gruber, R. et al, New Caledonian Crows Use Mental Representations to Solve Metatool Problems, https://doi.org/10.1016/j.cub.2019.01.008.

Holtmann B et al. Dominance relationships and coalitionary aggression against conspecifics in female carrion crows. doi: 10.1038/s41598-019-52177-7.

Hunt, G. Manufacture and use of hook-tools by New Caledonian crows. https://doi.org/10.1038/379249a0

Hunt GR, Villard P. Oscillatory extraction behaviour suggests functional attributes of crows’ hooked-stick tools. doi: 10.1007/s10071-023-01749-2.

Hunt GR et al. The crafting of hook tools by wild New Caledonian crows. doi: 10.1098/rsbl.2003.0085.

Hunt GR et al. Parallel tool industries in New Caledonian crows. doi: 10.1098/rsbl.2006.0603.

Hunt, G et al. (2016). A complex adaptive system may be essential for cumulative modifications in tool design. 10.2502/janip.66.2.2.

Jelbert SA et al. New Caledonian crows rapidly solve a collaborative problem without cooperative cognition. doi: 10.1371/journal.pone.0133253.

Jelbert SA et al. Using the Aesop’s fable paradigm to investigate causal understanding of water displacement by New Caledonian crows. doi: 10.1371/journal.pone.0092895.

Klump, BC. et al. Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials. https://doi.org/10.1186/s12915-015-0204-7

Mack C et al. Modulation of behavioural laterality in wild New Caledonian crows (Corvus moneduloides): Vocalization, age and function. doi: 10.1080/1357650X.2022.2098969.

McCoy, D.E. et al. New Caledonian Crows Behave Optimistically after Using Tools, https://doi.org/10.1016/j.cub.2019.06.080.

Müller, J.J.A. et al. Ravens remember the nature of a single reciprocal interaction sequence over 2 days and even after a month, https://doi.org/10.1016/j.anbehav.2017.04.004.

Rutz C et al. The evolutionary origins and ecological context of tool use in New Caledonian crows. doi: 10.1016/j.beproc.2011.11.005.

St Clair JJ, Rutz C. New Caledonian crows attend to multiple functional properties of complex tools. doi: 10.1098/rstb.2012.0415.

Swift, Kaeli et al. (2018). Occurrence and variability of tactile interactions between wild American crows and dead conspecifics. 10.1098/rstb.2017.0259.

Swift, K.N. et al, Wild American crows gather around their dead to learn about danger, https://doi.org/10.1016/j.anbehav.2015.08.021.

Troscianko, J. Et al. Activity profiles and hook-tool use of New Caledonian crows recorded by bird-borne video cameras. doi:10.1098/rsbl.2015.0777

Troscianko, J. et al. Extreme binocular vision and a straight bill facilitate tool use in New Caledonian crows. Nat Commun 3, 1110 (2012). https://doi.org/10.1038/ncomms2111

Uomini N, et al. Extended parenting and the evolution of cognition. doi: 10.1098/rstb.2019.0495.

Weir, Alex et al. (2002). Shaping of Hooks in New Caledonian Crows. 10.1126/science.1073433.

Weir, A.A.S., et al. A New Caledonian crow (Corvus moneduloides) creatively re-designs tools by bending or unbending aluminium strips. https://doi.org/10.1007/s10071-006-0052-5

Wimpenny JH et al. Cognitive processes associated with sequential tool use in New Caledonian crows. doi: 10.1371/journal.pone.0006471.

This episode sponsored by brilliant learn to think let me tell you about new Caledonian crows now I’m not talking about the old Caledonian crows those ones were idiots no the new Caledonian crows live on a group of islands called new calonia must be named after the crows one thing that new calonia has

Plenty of is wood but what they don’t have is wood peckers and that means there are plenty of insects and insects larae living in that wood that have not been peed and these are perfect good snacks for a bird that might have at them however for the crow the girth of

Their beess as well as a distaste for smashing their heads repeatedly into things has no doubt driven them into a certain cleverness new Caledonian crows may not have suitable peckers but what they do have is Crow sticks these crows have figured out how to use sticks to

Fish around for grubs and other things that have burrowed into logs and branches now this by itself isn’t that much of an achievement old Caledonian crows use sticks but all they did with them was Poke each other in the butt I mean it was funny they were voted most

Fun Crow the year they figured that out then they all starved to death anyway when they’re young new Caledonian crets learn how to make and use sticks from their parents and other adult crows here the one in the middle is the baby and you can see the adult on the left leave

A stick for the young one to take a turn with but it isn’t just about finding the right siiz dick and sticking it in a hole these Crow’s dicks are often shaped in a very specific way I mean before we even get to Sticks you can see what they

Do with the leaves of the pen danis on the right there you can see a tear started by a crow but what they’re really up to is making these the one on the left is a sort of basic instrument that takes advantage of the serrated

Edge of the leaf the one on the right though is made by a different group of crows and is more of a complex Swiss army knife you got something for any hole now these Leaf tools are well and good but if you want to make yourself a

Crow’s stick it’s going to depend on what you need it for listen if all you’re going to do is poke a spider and we’ve all been there I’m not going to try to sell you a fancy Crow stick stick all you need is something that puts some distance between you and said spider

When you poke it and listen you don’t need the top-of-the line stick to hunt for The larva of wood boring Petes now the trick with those is you keep poking them in the head with whatever you got eventually they just bite the end of the stick and you can pull them right out

But if you’re going after something that doesn’t just bite the end of a stick and has wedged itself all up in some tree cranny I mean then you need yourself a fancy Crow stick and let me tell you that’s a process first you have to cut yourself a little section off a plant

Now doesn’t look like much but the location of these first cuts are crucial and that’s because not every Crow’s dick is a Straight Shaft many of them have a hook on the end one way they make these hooks is first finding a fork in the

Stem of a plant from there you can see this one Cuts one of the branches right above the joint and then the next cut is on the stem right below the joint all right this one seems to be having a little trouble with that cut but here

You can see how those two cuts leave you with roughly a hook shape there’s a more boss way to do it which this one’s demonstrating you just grab one of the branches above the joint and tug on it really hard apparently if you do it right you get that hook shape without

All the cutting anyway once they’ve gotten to this point it’s time to clean things up a bit remove any extra Twigs or leaves that might be in the way but often these crows will also strip the bark off the business end of that stick and this might have a couple benefits

First it makes it smoother so there’s less friction when you use it but it also makes it lighter in color so the crow can see what’s going on down in the hole and seeing what they’re doing is quite important for these crows new Caledonian crows have these large

Forward-facing eyes this means there’s a greater area of binocular vision where what the right eye and left eye can see overlap in addition these crows have beaks that are fairly straight instead of being curved downward and this means that unlike their close relatives if they grab a tool with their beak it will

Be in the area where they have binocular vision now they can hold their Crow’s dick in a few different ways for a very small hole they might hold it off to the side that way you can get at least one eye really close but what they often do

Is point it forward but sort of hold it on one side bracing the back on their cheek and having it face forward gives them more options to see what’s going on and this is what the last step in making a crow’s dick is all about the crow

Bends the shaft so there’s a nice curve in it which helps them keep that hook tip where they can focus on it and that right there is a damn good Crow stick and the crows know it too when they make fine hook tools like that they don’t just leave around willy-nilly here’s a

Camera angle that you don’t see all that often outside of pornography and crow research apparently anyway science hippes put a camera on the bird’s tail feathers so they could see how they’re using these tools close up after they use a high value tool one that they put

A little elbow grease into they hold on to it with their little feets while they eat but come on Old Caledonian crows could make hooks too but they would put the hook end in their mouths and pretend they were caught fish voted best impression of a fish in Crow magazine

That year and then they all exploded Jerry I thought you said they starved to death oh because they were exploded no Jerry not being able to eat because you’ve been exploded is not a cause of death it’s never mind listen if you want to get smart like a crowby there’s a

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Or click on the link in the description the first 200 of you will get 20% off brilliant’s annual premium subscription and you’ll be supporting a brand that helps make this show possible try brilliant today where were we oh right perhaps more impressive than making these tools in the wild to hunt for

Grubs and such is this Crow’s ability to use the idea of a hook to solve a new problem here there’s a bucket of food with a handle on it down a tube the crow is given a straight metal stick and watch what it does with it bends the

Metal and then pulls that bucket right out so I guess the question is how smart are these little and how do you figure out what those little Noggin are capable of mean at this rate they’re going to steal all of our tiny buckets won’t have anything to put your weed in first off

It’s not just all about hooks they’re very good at selecting the right tool for a job the right length or diameter and if it’s not right they’ll modify it in this case it means thinning out a stick so it can be fit through a hole to

Push a little cup off a ledge and there you have it get all that work paid off now it’s time to oh that one’s the even smarter Crow but what about multistep problems in this case the food is pushed way back in that front tube there which comes equipped with a woefully short

Stick Betty that’s her name has to use the short stick to get a medium stick and then a medium stick to get a long stick and only then when she’s trying to figure out how she ended up in this escape room SL restaurant can she eat

Her food anyway straight A is for Betty now this Crow Pierre same challenge but he tries to skip a step trying to use the shortest tool to get the longest tool when that doesn’t work he gets pissed off and flies away only to come back with a natural sticky found which

Is the right size to get the long stick honestly I don’t know which one ought to hire I mean Betty certainly listens better but Pierre’s got some pluck but in this one they can always see all the tools that are available what happens when they can’t so in this restaurant

The food comes out if you drop a stone into that tube luckily around the corner there’s a stone but it’s pushed way back inside another tube keep going and you find basically the same thing except this time it has a stick in it also Out Of Reach this one’s a curveball meant to

Distract the crow you don’t need it because around the corner there’s a stick lying right in the open once it finds that it knows exactly what to do take the stick to the stone and the stone to the food while it ignores the unnecessary stick in a tube distraction

So it seems like they can keep track of those steps in their head Kur plunk num Noms and they tried this all sorts of different ways changing the order of things and add in distractions and shortcuts and the crows were able to hold it all in their heads and come up

With the right solution and if you think these crows are getting a little pissed off having to go through all this hoopla think again they seem to get some intrinsic pleasure out of using tools that goes beyond the food reward after using a tool they become more optimistic

And this could be a key to why they keep figuring new out like if you give them parts that fit together they can build new compound Tools in this scenario the sticks they’re given are too short but along with those sticks there’s parts of syringes scattered around like the tubes and the plungers

It’s like Venice Beach and without being shown these crows figured out how to put these pieces together to create a long enough tool but what if they’re really just good at sticks and don’t really understand cause and effect for example one question is whether they can use

Their smarts to figure out new Tools in situations they’re not used to there’s an asops fable about a crow that uses Pebbles to raise the water level in a pitch and new Caledonian crows do seem to learn how to do this to raise a bit

Of food floating in a tube now to see if the crow really understood what was happening they tried a few things for example giving them a wider tube and then an easier to fill narrow tube to see which one they’d go for they gave him an option of a tube filled with sand

I guess to weed out the idiots oh and this one’s interesting they had a setup where one of the outside tubes is connected to a center tube but out of sight under the table and the crow had to figure out which tube to put the rocks in anyway the results of all this

Seem to be a mixed bag these crows can certainly learn how to use new tools for new goals but they might just be using trial and error without having a real understanding so they can do quite a bit solo what about working together all right so you separate two crows but you

Put a box thing between them one crow has to pass a stone under a fence to another crow that Crow then drops the stone into a hole and then they both get food not a problem now we’ll mix it up a bit in this one that first Crow can make

A choice it can use its Stone to get a lower value treat dog food or it can pass the stone over to collaborate and get the good stuff and look at that they choose the good stuff problem is even if there’s no second Crow to pass the stone

To they often still try to pass the stone anyways I mean nobody wants to eat dog food Ravens also in the Crow family can learn to pull on strings together to get treats and they can learn to wait for each other and have preferences on who they want to collaborate with first

And during all these experiments you know the crows are studying the people too and if you’re a dick to a crow they’ll remember in this one for example the crow is is trained to go get a piece of bread and then exchange it for a piece of cheese but then they introduce

A new person who totally Reds on the deal look at that pops the cheese into their own mouth it’s so cold anyway given a choice even a month later that Crow won’t make any more cheese deals with that person and neither should you I mean it makes sense in the wild these

Birds have to navigate some complex social scenes and that starts with good communication and they’ve got good hardware for it a serx which looks like a failed prototype of a condom but this is so Real Deal equipment that lets them do all sorts of things communicate with

Each other with birds of other species and listen members of The Crow family are excellent mimics say hi hi I’m all right you all right all right so with all these abilities what are they up to what are they talking about right well let’s have a look at this charming scene all right

This one here is red she’s the dominant female caran crow in this joint so she makes a call to to this one over here whose code name is yellow yellow responds has a little head Bob but then listen to Red all right the science hippies hadn’t heard this sound before

But apparently it’s some Mafia level sh because after that red and yellow team up on another bird chasing it around and eventually pinning it on the ground and pecking at it another bird a bystander is all freaked out and tries to stop it but unfortunately the next morning the

Victim is dead and this happens in the wild too a dominant Crow will recruit others to get rid of the compettition I now when a crow dies or is found dead it’s a whole thing you’re right Jerry this one does look exploded now in this shot a science hippie has put a dead

Preserved Crow on the ground this dead crow is unknown to the local crows but they all come to check it out sometimes it’s referred to as a funeral butt brain sorry but brain scans have shown that the part of their brain that lights up is the decision-making part they’re

Trying to figure out what happened it’s not a funeral oh all right the the one seems to be having its way with the corpse and then there’s one doing it with that Crow all right but anyways you can see it’s not a funeral I mean at

Least not like the kind I’ve been to I mean I’m open to no actually I’m not I mean it would really change the decision- making around an open casket wouldn’t it I mean the old Caledonian crows they had some funerals like the real deal voted best funerals and then

They were all donged to death Jerry what does that even mean donged to death will I assume being hit by a dong oh many dongs no I’m not challenging you I’m just haven’t heard of it wait Did this also happen after they’d been exploded Jerry once something’s been exploded

Nothing that happens after is the cause of death no not even being hit by a dong not even a Crow’s