Clever Crows - bbc online

Clever New Caledonian crows can use three tools

By Rebecca Morelle Science reporter, BBC News

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Clever crows can use three tools

New Caledonian crows have given scientists yet another display of their tool-using prowess.

Scientists from New Zealand's University of Auckland have found that the birds are able to use three tools in succession to reach some food.
The crows, which use tools in the wild, have also shown other problem-solving behaviour, but this find suggests they are more innovative than was thought.
The research is published in the Proceedings of the Royal Society B.
The team headed to the South Pacific island of New Caledonia, the home of Corvus moneduloides.

Finding that the crows could solve the problem... was incredibly surprising Alex Taylor

They are the only birds known to craft and use tools in the wild.
The discovery that they whittle branches into hooks and tear leaves into barbed probes to extract food from hard-to-reach nooks astounded scientists, who had previously thought that ability to fashion tools was unique to primates.
And further research in the laboratory and the field has revealed that New Caledonian crows are also innovative problem solvers, often rivalling primates. Experiments have shown that the birds can craft new tools out of unfamiliar materials, as well as use a number of tools in succession.

1. String is attached to perch 2. Short stick attached to string 3. Long stick out-of-reach behind bars - can be reached with short stick 4. Out-of-reach scrap of meat - can be reached by long stick

To further understand how the birds perform these tasks, the University of Auckland team set seven wild crows, which had temporarily been captured and placed in an aviary, a complicated problem.
The birds were presented with some out-of reach food; a long tool, which could be used to extract the food, but which was also out of reach, tucked behind the bars of a box; and a short tool, which could be used to extract the long tool, but which was attached to the end of a dangling piece of string tied to the crow's perch.

In the wild, New Caledonian crows craft tools to fish for food

Professor Russell Gray, from the University of Auckland, explained: "The crows needed to understand they needed the short tool on the piece of string to get the long tool, and then use the long tool to get the food."
The seven birds were split into two groups.
The first group of birds were given the chance to try out every individual step in the set-up, before they were presented with the complete multi-stage task.
Professor Gray said: "All these birds had to do was to put together things they could already do in the right sequence."
Each of the three birds managed to solve the three-stage problem on their first attempt.
A second group of birds was presented with a less familiar situation.
While they had previously been shown tasks where food was directly attached to string, and sticks could be used to grab out of reach food, they had never been given a situation where a tool was linked to the string or where one tool was needed to collect a second tool.
However, when presented with the multi-stage task, these birds also managed to reach their treat.

Meet the brains of the animal world

One bird, Sam, spent 110 seconds inspecting the apparatus before completing each of the steps without any mistakes. Another bird, Casper, also completed on his first try, although he was initially puzzled by the string.
The other two birds solved the problem on their third and fourth attempts.
Alex Taylor, the lead author of the paper, said: "Finding that the crows could solve the problem even when they had to innovate two behaviours was incredibly surprising."
The researchers say that the experiments are helping to shed light on how the crows are carrying out these complicated tasks.
Dr Taylor said that while using or creating a single tool could be underpinned by simple learning processes, solving a set of linked problems, suggested that the basis for their innovation is much more complex.

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Rooks have also been studied as problem solvers - here one repeats Aesop's ancient fable

New Caledonian crows form part of the corvid family of birds, which also include crows, ravens, rooks, jackdaws, jays and magpies.
Over the decades, these birds have been studied for their apparent intelligence.
Scientists have been surprised to find western scrub jays that try to deceive their fellow birds by pretending to bury food while they are being watched, jays which perform remarkable feats of memory, and possibly even self-recognition in magpies.
More recent studies have also found that rooks too are able to create and use tools - even though, unlike New Caledonian crows, they have not been seen to use them in the wild.

Octopus snatches coconut and runs

And these birds have also surprised scientists with their problem-solving abilities - most recently, they have been shown to repeat Aesop's fable, by working out that dropping stones into water will raise its height, giving them access to some floating food.
But it might not just be birds and primates with tool-using skills - in late 2009, a paper published in the journal Current Biology suggested that veined octopuses in Australia were using halved coconut shells as tools, by scooping them from the seabed, galloping off with them and then later using them as a shelter.
However, some researchers debate whether this kind of behaviour fits the definition for tool-use.

(Note: This story appeared on BBC Online on Tuesday, April 20, 2010.)

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Rooks reveal their brains - BBC Online

Rooks reveal remarkable tool use

By Rebecca Morelle Science reporter, BBC News

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Rooks select the appropriate stones to retrieve a tasty snack (Footage: Christopher Bird)

Rooks have a remarkable aptitude for using tools, scientists have found.

Tests on captive birds revealed that they could craft and employ tools to solve a number of different problems.

The findings, published in the Proceedings of the National Academy of Sciences, came as a surprise as rooks do not use tools in the wild.

Despite this, the UK team said the birds' skills rivalled those of well-known tool users such as chimpanzees and New Caledonian crows.

Dr Nathan Emery, from Queen Mary, University of London, an author of the paper, said: "The study shows the creativity and insight that rooks have when they solve problems."

The scientists focused on four captive rooks: Cook, Fry, Connelly and Monroe, and discovered that the birds were able to use tools in a number of ways to solve a variety of problems.

Meet the brains of the animal world

For example, the birds were presented with a vertical tube, running down to a trap-door with an out-of-reach worm perched upon it, as well as a number of different-sized stones placed nearby.

The scientists discovered that the rooks would select the largest stone, which was heavy enough to push open the trap-door when dropped and release the snack.

And when given a selection of different-shaped stones, some of which could fit into the tube some of which could not, the rooks opted for a tool that would give them access to the treat.

Lead author Christopher Bird, from Cambridge University, said: "We have found that they can select the appropriate tools out of a choice of tools and they show flexibility in the types of tools they use."

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The test revealed that rooks can use two tools in succession to get the worm

The researchers also found the rooks could use two tools in succession - something that is described as metatool use.

They gave the birds a large stone, as well as two vertical tubes, one wide, with a small stone perched at the bottom on a trap-door, and another thin, this time containing a worm.

They found that the rooks would first drop the large stone into the wide tube, releasing the smaller stone, and subsequently drop this stone into the thin tube to free the tasty treat.

Until now, metatool use has only been seen in great apes and New Caledonian crows.

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The rooks were able to fashion wire into a hook to fish out the bucket of food

Perhaps most surprisingly, the team also revealed that rooks could modify and create new tools.

They found that the rooks would bend a piece of straight wire into a hook so that they could retrieve a retrieve a bucket laden with food from the bottom of the vertical well.

Until now, this novel tool-fashioning behaviour has only been reported for a single New Caledonian crow called Betty. But in this study, three of the four rooks spontaneously created the hook in their first trial.

Bird brains?

Mr Bird told BBC News: "It was a big surprise to find out that rooks could use tools.

"We've seen this kind of tool use in New Caledonian crows, but the interesting thing about the rooks is that they do not use tools in the wild."

Both rooks and New Caledonian crows belong to the corvids, a bird group that is renowned for intelligent behaviour.

Rooks are a member of the corvid family

However, until now, it was thought that sophisticated tool-use was limited to New Caledonian crows, a species found on the island of New Caledonia in the Pacific, which create tools to pluck grubs from holes.

Mr Bird said: "Tool use is probably very important for these crows because of their ecology - they may get a large proportion of the protein they need from these grubs.

"And it has been suggested that tool-use is a trait unique to that species that might have evolved because of ecological pressures."

But the finding that rooks can use tools now raises questions about how this special ability might have come about.

Mr Bird said: "Rooks don't have the same pressures [as New Caledonian crows]. In the wild they don't need tools - they have lots of access to other sources of food, like carrion, human rubbish, and seeds from agriculture, things like that."

The researchers said that this could mean that an ancient ancestor of the corvids might have evolved the capacity to use tools as well as a complex understanding of the physical properties of materials.

Dr Emery told BBC News: "Because they don't use tools in the wild, the question is why should they have evolved the ability to use tools in the lab and understand the properties of those objects as tools?

"Is this a form of general intelligence that has been co-opted for tool use?"

The researchers say the finding raises the possibility that other corvid species may also have possess an innate ability to use tools.

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