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Crows

I remember watching something about some crows who lived near the sea who had developed a taste for shellfish and crabs, just general stuff like that but nobody could tell how the birds were breaking open the shells.
After some careful observation they discovered that the crows would wait at traffic lights. When the light went red they would strut their stuff out into the road and place their shellfish under the front wheel of the nearest stationary car. Once the light changed back to green the car drove on and thus cracked the shell open allowing the crow to have it's meal.
I tell you it's only a matter of time before they have can openers.
 
Crows and Chimps

I skimmed through an old book by Carl Sagan recently which contained a graph of estimated intelligence for various species. Crows were shown as somewhat less intelligent than chimps but were certainly up there--smarter than dogs perhaps.

We humans do tend to be a bit chauvinistic about intelligence (we define intelligence as anything a human can do that a machine or animal can't do, for example, and our "intelligence" is therefore shrinking as machines and animals get smarter), but I don't think crows are smarter than chimps. Dogs, quite possibly, cats even more likely, pigs, I wouldn't be sure, but not chimps.

Chimps have bigger vocabularies and show more aptitude for independant creativity of thought. They also make tools (in the wild as well as in captivity) and they pass this knowledge on to their young. They therefore have a primitive culture.

I do love ravens and crows, though. They have a sort of cheeky, cockney charm. Mind you, large flocks of them can be extremely destructive and intimidating. But then, so could a troop of chimps or a pack of feral dogs.

Many kinds of animals have demonstrated many elements of supposedly human intelligence.

There is plenty of evidence that counting is widespread among the animals that care for their young--after all, how is a mother to know if she has lost a few nestlings if she can't count?

Also, many animals (elephants, baboons, monkeys, crows) etc. have demonstrated an ability to be vindictive as well as good memories by waiting for a car or person who has injured or killed a member of their group for days and then attacking them.

Intelligence seems to be necessary to animals that live in packs, especially predators. You have to be able to determine whether you have all your pups, and whether the pack you just met is bigger or smaller than yours. You have to remember who your friends and enemies are, where food supplies are to be found and at what time of the year, and many other things.

Even dumb sheep can remember a face for a couple of years or three.
 
Re: Crows and Chimps

littleblackduck said:
Even dumb sheep can remember a face for a couple of years or three.
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Dirty, dirty boy!:)

Only kidding, pal!

I love the way that crows will walk from one place to another.
It is only an imminant theat that will shift them to the sky.
As you said, they are cheeky and charming. They will hold their position until it becomes really neccessary to move.
A rabbit will freeze until it is caught whereas a crow will be constantly aware of the presence of a predator.
Only when the predator is up close, will the crow move off.
Even then, they might just swagger off rather than fly.
 
crows from Hell

I know crows also have a wicked sense of humor. My grandmother used to tell me stories about her kids and their pet crows. The crows were always doing things specifically just to wind her up, like carefully filling the end of the garden hose with as many little pebbles and things as they could get in there and then hang around laughing maniacally as she would curse and shout at them when she tried to water the garden. Stealing things is a favorite pastime, not just shiny things they might think are pretty but things they've seen you handling. For some reason they think it's funny to swipe your watch if you lay it down or the tools you're using to fix your car. The buggers did that one to me. They paraded up and down a nearby tree branch with a stolen screwdriver or something taunting me and making all sorts of noise that you could tell was sinister bird laughter. I grew up on a farm in the Midwest and know a lot of animals have a sense of humor and some are capable of quite bizarre practical jokes.
 
While on the subject of crows, over the last ten years or so has anyone else noticed that there are a lot more crows with grey to white patches on the upper parts of their wings (that can only be seen when the bird is in flight), there has always been a few but am seeing lot more of them lately,in the last five years especialy. Is this happening in other parts of the country?.
 
beakboo said:
What about those monkeys (Japanese macaques?) who started washing their potatoes in sea water? There was much made of it at the time.
Oll- domestic cats?? Surely not? What are your sources here, I'm intrigued. :)
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Now beakaboo, my cat has been training me for more that 19yrs, evidently I'm a very slow learner. She wakes me to be fed, lets me know when its time for her cream, or if she just wants to be picked up and patted. Yes, it took ninteen years for me to learn that. She learned what behavior of hers would get my attention then took it up a notch until she got the result she finally wanted. no tools involved. 'cept myself o'course.
 
Michael Wason said:
While on the subject of crows, over the last ten years or so has anyone else noticed that there are a lot more crows with grey to white patches on the upper parts of their wings (that can only be seen when the bird is in flight), there has always been a few but am seeing lot more of them lately,in the last five years especialy. Is this happening in other parts of the country?.
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I'm not paticularly observant, butt I've noticed a lot of crows lately masquerading as magpies.
 
STONE THE CROWS


16:00 - 03 April 2004

Clever birds work it all out and get trains to do their heavy work for them

Mike Fairgrieve

RAIL police were flapping when they found small pebbles and gravel on stretches of North-east railway sleepers.

But you could have knocked them down with a feather when they discovered the bird-brained culprits were crows!

Sgt Mike Burnett of British Transport Police said: "The problem was spotted by an engineer doing maintenance work.

"It was first reported as people putting stones on the line.

"But something did not make sense. It was out at Kennethmont and Huntly and that's not an area where we would expect trouble.

"Our first thought was kids, but it's in the middle of nowhere."

Then an eagle-eyed signal operator solved the mystery.

Mike said: "He spotted the birds putting them on the lines so the trains would go over them."

It turns out the crows know exactly what they're doing.

They place the stones on the tracks, wait for trains to run over them, then swallow the debris, which helps them digest their food.

At first Mike thought it was a wind-up.

"I checked the date to see it wasn't April 1.

"I've been in this job for 20 years and never known anything like it."

It was also news to Julia Harris, of the Royal Society for the Protection of Birds.

She said: "I've never heard of that before, but crows are definitely known as being among the most inventive birds, like others from the same family such as jackdaws."

She says crows and other birds have no teeth so they need to swallow grit to help them grind up their food.

A ScotRail spokesman said: "I think that's absolutely amazing. It sounds like something out of Alfred Hitchcock's The Birds."

But he didn't think the rail company would be taking any measures to clip the culprits' wings.

He said: "We have enough problems already with people putting washing machines and allsorts on railway lines.

"At least these birds are doing something for a proper purpose. This is a serious part of their life," he said.

The tale of the brainy birds coincides with a major conference in Aberdeen today.

The 8th International Seabird Group Conference, being held in the city today and tomorrow, was being told that Aberdeen is believed to have the world's biggest population of roof-nesting herring gulls.

It had been hoped that Aberdeen's refuse switch from black bags to wheelie bins would put an end to the gull menace.

But the large birds, with the characteristic blood-red mark on their beaks, have not been completely run out of town.

Conference organiser Martin Heubeck said: "I'm not surprised. Wheelie bins alone won't solve the problem.

"Walk down Union Street at 3am on Sunday and you will see the leftovers from takeaways scattered all over the place.

"So there's still a food source readily available."

During another recent visit to the Granite City he could see that there were still plenty of nesting spots.

He said: "I was staying at the Travel Lodge on Union Street a week ago and I could see a flat roof on Bridge Street which was heaving with herring gulls.

"But they could easily have been prevented from nesting there by putting up wires."

Herring gulls and other seabirds, like black-headed gulls, have moved to coastal areas and inland in larger numbers since the 1980s and the 1990s.

And, like foxes, they have taken root in many of our towns and cities, feasting on leftovers.

Ironically Seabird 2000, the largest survey of UK seabirds in 15 years, shows that UK numbers of herring gulls have declined in the past 30 years.

Mr Heubeck says that's taking the total over all. The numbers in coastal areas have fallen as the gulls move into the towns.

Herring gulls have taken a dive along with Arctic skuas, shags, kittiwakes and some species of tern.

But the good news is that there have been big rises in the populations of gannets guillemots and - everyone's favourite - puffins.

Britain has 8 million seabirds and 5.2 million are in Scotland.

Nobody has yet counted how many are perched on Aberdeen's rooftops.
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http://www.thisisnorthscotland.co.u...layContent&sourceNode=83936&contentPK=9457726
 
I have always wondered how bluetits know there is milk in milk bottle.
They dont have much of a sense of smell (if any)

I only assume that once a bird saw a human drink milk out of the bottle and decided they would try some too.
 
I doubt that bluetits get the chance to do that these days, so few people have milk delivered.
 
We get our milk at work delivered in bottles and the bluetits there pierce the tops. No trouble with milk delivered at home, though.

Carole
 
Homo Aves said:
I have always wondered how bluetits know there is milk in milk bottle.
They dont have much of a sense of smell (if any)

I only assume that once a bird saw a human drink milk out of the bottle and decided they would try some too.
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Interesting info here.
 
Interesting article about the Bluetit.

Perhaps a bit off topic and maybe a stupid question as well...We live in an area that has a pretty good population of hawks. On more than one occasion I have seen crows and sometimes smaller birds harrassing a hawk. Perhaps it's a territorial thing or the other bird protecting young...but sheesh, it's a hawk. I've seen them carrying prey larger then themselves. As a bird of prey why would it let itself be bullied like that?
 
Very common for songbirds and crows to mob hawks, falcons and owls, seen it often, herons also get mobbed.
 
Maybe the songbirds think its not right for them to be eaten.;)
 
For some of the earliest and still best discussions of animal intelligence, read Konrad Lorenz.

About mobbing...I've watched mockingbirds chase off an eagle. It appears that the smaller birds are able to manuver better and stay above and behind the intruder. Makes it easier to drive them off.

At University of Arizona is Alex the African Grey Parrot. Alex not only knows colors and shapes and such, but recognizes textures, materials, and such details as the difference between a truck and a car. He can combine any of these. IE, told to go to a selection of items and pick the blue wooden car, he can. Dr. Irene Pepperberg is his handler/researcher.

Border collies are a great example of what dogs are capable of. My grandfather had one to herd his dairy cattle. He told the dog, take the cows, and the dog would herc them out to the pasture. In the evening, it was go get the cows. If you've ever watched sheep dog trials, you'll understand better how smart these guys are. Nothing but subtle hand signals are used.
 
I have heard many amazing stories about sheepdogs...

One would never work with a shepherd, he used to go out after the shepherd had come home and glean the sheep he had missed!
 
Pete Younger said:
Are Crows more intelligent than Chimps, it seems they are capable of making tools. have a look.
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It is looking that way:

Emery, N.J. & Clayton, N.S. (2004) The mentality of crows: Convergent evolution of intelligence in corvids and apes. Science. 306 (5703). 1903 - 7.

Discussions of the evolution of intelligence have focused on monkeys and apes because of their close evolutionary relationship to humans. Other large-brained social animals, such as corvids, also understand their physical and social worlds. Here we review recent studies of tool manufacture, mental time travel, and social cognition in corvids, and suggest that complex cognition depends on a "tool kit" consisting of causal reasoning, flexibility, imagination, and prospection. Because corvids and apes share these cognitive tools, we argue that complex cognitive abilities evolved multiple times in distantly related species with vastly different brain structures in order to solve similar socioecological problems.
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A report:

Crows as Clever as Great Apes, Study Says

James Owen in London
for National Geographic News
December 9, 2004

Anyone who has watched crows, jays, ravens and other members of the corvid family will know they're anything but "birdbrained."

For instance, jays will sit on ant nests, allowing the angry insects to douse them with formic acid, a natural pesticide which helps rid the birds of parasites. Urban-living carrion crows have learned to use road traffic for cracking tough nuts. They do this at traffic light crossings, waiting patiently with human pedestrians for a red light before retrieving their prize.

Yet corvids may be even cleverer than we think. A new study suggests their cognitive abilities are a match for primates such as chimpanzees and gorillas. Furthermore, crows may provide clues to understanding human intelligence.

Published tomorrow in the journal Science, the study is co-authored by Nathan Emery and Nicola Clayton, from the departments of animal behavior and experimental psychology at Cambridge University, England.

They say that, while having very different brain structures, both crows and primates use a combination of mental tools, including imagination and the anticipation of possible future events, to solve similar problems. They base their argument on existing studies.

Emery and Clayton write, "These studies have found that some corvids are not only superior in intelligence to birds of other avian species (perhaps with the exception of some parrots), but also rival many nonhuman primates."

Increasingly, scientists agree that it isn't physical need that makes animal smart, but social necessity. Group living tends to be a complicated business, so for individuals to prosper they need to understand exactly what's going on. So highly social creatures like dolphins, chimps, and humans tend to be large-brained and intelligent.

Large Brains

The study notes that crows are also social and have unusually large brains for their size. "It is relatively the same size as the chimpanzee brain," the authors said.

They say that crows and apes both think about their social and physical surroundings in complex ways, using tool use as an example.

Like apes, many birds employ tools to gather food, but it isn't clear whether chimps or crows appreciate how these tools work. It may be that they simply discover their usefulness by accident. However, studies of New Caledonian crows, from the South Pacific, suggest otherwise.

New Caledonian crows manufacture two very different types of tool for finding prey. Hooks crafted from twigs are used to poke grubs from holes in trees, while they also cut up stiff leaves with their beaks, carefully sculpting them into sharp instruments for probing leaf detritus for insects and other invertebrates.

A New Caledonian crow in captivity learned how to bend a piece of straight wire into a hook to probe for food. (Watch a video of the crow doing this.)

Such sophisticated tool manufacture and use is unique in non-human wild animals, according to Jackie Chappell, a UK-based zoologist who has studied the birds.

Emery and Clayton compare the crow's handiwork to minor human technological innovations. And because different New Caledonian crow populations make these tools to slightly different designs, some scientists take this as evidence of some form of culture, as has been suggested in chimpanzees.

Other corvids may use memories of past experiences to plan ahead.

In the case of Western scrub jays, a previous study by Emery and Clayton suggests jays with past experience of pilfering food caches collected by other jays can then use this knowledge to protect their own caches.

Lab experiments showed that if a habitual thief was observed while burying its own cache, it would later go back and move it when no other bird was looking. Meanwhile, "innocent" jays did not exhibit the same cunning.

Imagination?

The researchers also argue that such behavior suggests Western scrub jays are able to second guess another's intentions, or, to put it another way, get into another bird's mind. In which case, this could be evidence for imagination.

Emery and Clayton write, "Western scrub jays may present a case for imagination because the jays needed to have remembered the previous relevant social context, used their own experience of having been a thief to predict the behavior of a pilferer, and determined the safest course of action to protect the caches from pilferage."

Studies to assess similar cognitive abilities in apes have been inconclusive, according to John Pearce, professor of psychology at Cardiff University in Wales.

"[The Western scrub jay study] is some of the best evidence going that one animal can understand what another is thinking," he added.

Pearce believes we can gain insights into the basic mechanisms of human intelligence through the study of animals. He says language is generally considered to be one of the major divisions between human and animal intelligence, which makes Western scrub jays especially noteworthy.

He said, "What's so interesting is that while Western scrub jays may not have language, the research shows they've got many of the intellectual abilities that humans have. This suggests that many of our intellectual abilities which we think we need language for perhaps we don't in fact need language for. That then makes us try to understand these abilities in a different way."

If we're as smart as we think we are, perhaps we need to keep an even closer eye on those clever old crows.
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Source
 
Chimps have the advantage of having hands that can manipulate the tools in all sorts of ways. They can experiment through trial and error and eventually come up with something that works. The crow seems to do most of that in its head.


"Once upon a midnight dreary, while I pondered weak and weary,
Over many a quaint and curious volume of forgotten lore,
While I nodded, nearly napping, suddenly there came a tapping,
As of some one gently rapping, rapping at my chamber door.
`'Tis some visitor,' I muttered, `tapping at my chamber door -
Only this, and nothing more.'"

EAP
 
I love it when scientific articles talk about the intelligence of 'animals' compared to humans... we're animals!! Despite whatever Christianity (or other faiths) has to say, the evidence points to evolution, IMHO. We're just another species competing for resources, albeit with a great degree of success. Our own particular vantage point, our "intelligence" is based upon our perception of self-awareness. Other species self-awareness and methods of communication are different enough from ours that we tend to diminish their capacity to control their environment, learn, or 'think'.

That being said, I have been delighted by the antics of a large crow that assaulted a trash can outside of the cafeteria at work. It would always seem to announce it's arrival, cawing loudly from an unseen vantage point, then swoop down to the can. It would then strut about on top of the can, challenging bystanders (or perhaps just asserting it's right to the garbage) and energetically toss styrofoam trays out onto the ground. The cool thing was that this crow knew that the closed trays held food, and would tear the styrofoam apart to get at the food inside. Maybe the way this crow learned to associate closed trays with food is simple (open tray w/food residue + smell = associating closed tray w/food?), but I respected it's ingenuity, and besides it livened up an otherwise boring lunch break.
 
The crows that know how to make tools

By Roger Highfield
(Filed: 13/01/2005)

The Einsteins of the avian world - crows that live on an isolated Pacific island - are even more intelligent than originally thought, according to a study published today.

Thinkers as diverse as Freud, Engels and Thomas Carlyle once pointed to the use of tools as defining behaviour of human beings.

Then it was found that many animals also used them, from the "fishing sticks" of apes to the rocks dropped on ostrich eggs by Egyptian vultures.

The crows of New Caledonia (Corvus moneduloides) are among the creatures that rival Man in his dexterity. They can fashion tools from leaves and even develop designs for a specific task.

Today, in the journal Nature, a team from Oxford University reports that young crows can even make and use tools without being taught and without ever having seen an adult crow doing the same thing, making them the first vertebrate creature whose young seem to be "programmed" to do this.

The young birds instinctively seize twigs in their beaks and use them to retrieve food from crevices, according to Prof Alex Kacelnik and Benjamin Kenward, Alex Weir and Christian Rutz.

The team describes how four young crows in captivity all learned to use twigs as tools before they were 80 days old. Two were allowed to watch human demonstrations of similar tool use, but the others learned the skill purely by instinct.

"Although spontaneous tool use has been observed in many animals, to our knowledge, ours is the first report of spontaneous tool manufacture in a naive juvenile vertebrate," said Prof Kacelnik.

But learning from others in the wild may influence different styles.

In the wild, studies revealed how adults tear the leaves of the pandanus (screw pine) into a distinct stepped shape. The captive crows, despite producing a range of different shapes, did not.
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Source
 
More on those clever crows.

Crows make monkeys out of chimps in mental test
Crows
00:01 17 September 2008
NewScientist.com news service
Emma Young

Crows seem to be able to use causal reasoning to solve a problem, a feat previously undocumented in any other non-human animal, including chimps.

Alex Taylor at the University of Auckland, New Zealand, and his team presented six New Caledonian crows with a series of "trap-tube" tests.

A choice morsel of food was placed in a horizontal Perspex tube, which also featured two round holes in the underside, with Perspex traps below.

For most of the tests, one of the holes was sealed, so the food could be dragged across it with a stick and out of the tube to be eaten. The other hole was left open, trapping the food if the crows moved it the wrong way.

Three of the crows solved the task consistently, even after the team modified the appearance of the equipment. This suggested that these crows weren't using arbitrary features – such as the colour of the rim of a hole – to guide their behaviour. Instead they seemed to understand that if they dragged food across a hole, they would lose it.

Not-so great apes
To investigate further, the team presented the crows with a wooden table, divided into two compartments. A treat was at the end of each compartment, but in one, it was positioned behind a rectangular trap hole. To get the snack, the crow had to consistently choose to retrieve food from the compartment without the hole.

A recent study of great apes found they could not transfer success at the trap-tube to success at the trap-table. The three crows could, however.

"They seem to have some kind of concept of a hole that isn't tied to purely visual features, and they can use this concept to figure out the novel problem," Taylor says. "This is the most conclusive evidence to date for causal reasoning in an animal."

Three of the crows did fail at both tasks, however. The team plans further work to investigate why.

Journal reference: Proceedings of the Royal Society B
(DOI: 10.1098/rspb.2008.1107) http://publishing.royalsociety.org/index.cfm?page=1569


Related Articles

Six 'uniquely' human traits now found in animals
http://www.newscientist.com/article.ns?id=dn13860
22 May 2008

Crows wield tools with human-like skill
http://www.newscientist.com/article.ns?id=dn12495
16 August 2007

Tool use by shy crows caught on camera
http://www.newscientist.com/article.ns?id=dn12738
04 October 2007

Weblinks

Wild New Caledonian tool use explained by Russell Gray
http://www.youtube.com/watch?v=QNaZ3EoWnZg

Metatool use explained by Russell Gray
http://www.youtube.com/watch?v=nIwsNvCk ... re=related

Videos of tool use in crows
http://language.psy.auckland.ac.nz/crow ... -clips.htm

Crow research team, University of Auckland
www.language.psy.auckland.ac.nz/crows/
 
I love crows and am always surprised by their intelligent and unfathomable behaviour:

Our train was late at the Berlin Hauptbahnhof. Fresh snow was falling. Up on the high roof a crow was doing something mysterious - I think it was taking a "snow bath". It was entertaining to follow it's progress along the roof. There must be some bird logic behind the path it traced.

Picture here:
http://www.flickr.com/photos/uair01/4230386567/
 
Crows can 'reason' about causes, a recent study finds
http://www.bbc.co.uk/nature/19626912

A New Caledonian crow using a tool

Related Stories

Clever crows can use three tools
Crows know familiar human voices
Crows use mirrors to find food

Tool-making crows have the ability to "reason", say scientists.

In an experiment, researchers found that crows were more likely to forage when they could attribute changes in their environment to a human presence.

This behaviour may suggest "complex cognition", according to a study published in the Proceedings of the National Academy of Sciences.

Until now the ability to make inferences based on causes has been attributed to humans but not animals.

Continue reading the main story
Bird brained?


Watch a Carrion crow use a lorry as a nutcracker - and a pedestrian crossing as a dining table
See a New Caledonian crow turn a twig into a harpoon
See 40,000 rooks and jackdaws synchronise their roost
The study was a collaboration between researchers from the University of Auckland, New Zealand, the University of Cambridge, UK and the University of Vienna, Austria.

In their experiment eight wild crows used tools to remove food from a box.

Inside the enclosure there was a stick and the crows were tested in two separate series of events that both involved the stick moving.

In one instance a human entered the hide and the stick moved. In the other, the stick still moved but no human entered.

On the occasions when no human was observed entering the hide, the crows abandoned their efforts to probe for food using a tool more frequently than they did when a human had been observed.

According to the scientists, the study proved that crows attributed the stick's movement to human presence.

The results indicated that neither age nor sex was a predictor of the behaviour with juveniles, males and females displaying the same behaviour.


Watch the crows being put through their paces
Scientists said that the kind of "reasoned inference" shown by the New Caledonian crows under these controlled conditions could also be utilised in the wild to anticipate danger or food.

The study is the first to suggest that animals have the ability to make reasoned inferences, although scientists added that the phenomenon could be more common among animals than previously thought.
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A crow gave me a fright today. Great big "CAW!" right behind me. Reading that I realise it did so deliberately.
 
Those crows over there. they know what you are thinking and they're laughing at you.

Are Crows Mind Readers ... Or Just Stressed Out?
http://news.sciencemag.org/sciencenow/2 ... tml?ref=hp
by Michael Balter on 10 January 2013, 3:25 PM | 0 Comments

Who took my food? A new study supports claims that Western scrub jays can read each others' minds.

Are crows mind readers? Recent studies have suggested that the birds hide food because they think others will steal it -- a complex intuition that has been seen in only a select few creatures. Some critics have suggested that the birds might simply be stressed out, but new research reveals that crows may be gifted after all.

Cracks first began forming in the crow mind-reading hypothesis last year. One member of a research team from the University of Groningen in the Netherlands spent 7 months in bird cognition expert Nicola Clayton's University of Cambridge lab in the United Kingdom studying Western scrub jays, a member of the crow family that is often used for these studies. The Groningen team then developed a computer model in which "virtual jays" cached food under various conditions. In PLOS ONE, they argued that the model showed the jays' might be moving their food—or recaching it—not because they were reading the minds of their competitors, but simply because of the stress of having another bird present (especially a more dominant one) and of losing food to thieves. The result contradicted previous work by Clayton's group suggesting that crows might have a humanlike awareness of other creatures' mental states—a cognitive ability known as theory of mind that has been claimed in dogs, chimps, and even rats.

In the new study, Clayton and her Cambridge graduate student James Thom decided to test the stress hypothesis. First, they replicated earlier work on scrub jays by letting the birds hide peanuts in trays of ground corn cobs—either unobserved or with another bird watching—and later giving them a chance to rebury them. As in previous studies, the jays recached a much higher proportion of the peanuts if another bird could see them: nearly twice as much as in private, the team reports online today in PLOS ONE.



Then came the stress test. First, Thom and Clayton gave the jays trays with the ground cobs but no food to hide in them—a so-called "sham" session. Then, in a second session, they gave the birds new hiding trays and bowls of peanuts to hide. When the jays were done, the experimenters removed the trays and stole all of the peanuts. Finally, after a short break, the researchers gave each bird yet another round of food, a new tray to hide it in, and one of the trays it had seen earlier: either the sham tray or the ransacked "pilfer" tray. The jays had 10 minutes for recaching.

If the Groningen model was correct, Thom and Clayton argue, the stress of discovering that food was missing from the pilfer tray ought to drive jays to cache more peanuts than those presented with the sham tray. In fact, there was no difference, even though corvids have excellent memories for hidden food and remarkable abilities to find it again. The hypothesis that jays have theory of mind remains on the table, Thom says.

Thom and Clayton have "definitely shown that scrub recaching is not as simple as the [Groningen] model presents it," says Elske van der Vaart, lead author of the Groningen team's earlier report, who is now at the University of Amsterdam. But she argues that there is still room for doubt about what the results mean. For example, the sham condition—in which the jays had no food to cache—could have stressed the birds as much as the stolen peanuts in the pilfer condition did.

Amanda Seed, an animal cognition researcher at the University of St. Andrews in the United Kingdom, says the Groningen model's failure to predict the birds' caching behavior in the new experiments could "bring the model down like a pack of cards." But researchers still have to rule out other possible explanations, she says. For example, the birds given pilfered tray may have noticed the missing peanuts too late to affect their overall caching rate, or they may have spent much of their time looking for the missing nuts instead of hiding the new ones. The Cambridge and Groningen groups are planning more work with both real and "virtual" birds to see what is really going on. "I applaud them for rising to the challenge," Seed says.
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Crows understand water displacement at the level of a small child: Show causal understanding of a 5- to 7-year-old child
Date:
March 26, 2014

Crows understand water displacement at the level of a small child.
Credit: Sarah Jelbert; CC-BY

New Caledonian crows may understand how to displace water to receive a reward, with the causal understanding level of a 5-7 year-old child, according to results published March 26, 2014, in the open access journal PLOS ONE by Sarah Jelbert from University of Auckland and colleagues.

Understanding causal relationships between actions is a key feature of human cognition. However, the extent to which non-human animals are capable of understanding causal relationships is not well understood.

Scientists used the Aesop's fable riddle -- in which subjects drop stones into water to raise the water level and obtain an out-of reach-reward -- to assess New Caledonian crows' causal understanding of water displacement. These crows are known for their intelligence and innovation, as they are the only non-primate species able to make tools, such as prodding sticks and hooks. Six wild crows were tested after a brief training period for six experiments, during which the authors noted rapid learning (although not all the crows completed every experiment). The authors note that these tasks did not test insightful problem solving, but were directed at the birds' understanding of volume displacement.

Crows completed 4 of 6 water displacement tasks, including preferentially dropping stones into a water-filled tube instead of a sand-filled tube, dropping sinking objects rather than floating objects, using solid objects rather than hollow objects, and dropping objects into a tube with a high water level rather than a low one. However, they failed two more challenging tasks, one that required understanding of the width of the tube, and one that required understanding of counterintuitive cues for a U-shaped displacement task. According to the authors, results indicate crows may possess a sophisticated -- but incomplete -- understanding of the causal properties of volume displacement, rivalling that of 5-7 year old children.

Sarah Jelbert added, "These results are striking as they highlight both the strengths and limits of the crows' understanding. In particular, the crows all failed a task which violated normal causal rules, but they could pass the other tasks, which suggests they were using some level of causal understanding when they were successful.
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Story Source:
The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.

Journal Reference:
Sarah A. Jelbert, Alex H. Taylor, Lucy G. Cheke, Nicola S. Clayton, Russell D. Gray. Using the Aesop's Fable Paradigm to Investigate Causal Understanding of Water Displacement by New Caledonian Crows. PLoS ONE, 2014; 9 (3): e92895 DOI: 10.1371/journal.pone.0092895

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PLOS. "Crows understand water displacement at the level of a small child: Show causal understanding of a 5- to 7-year-old child." ScienceDaily. ScienceDaily, 26 March 2014.

<www.sciencedaily.com/releases/2014/03/140326182039.htm>.
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