Ravens, Crows, Jays, Magpies
Masters of Deceit
Method is more important than strength, when you wish to control your enemies.
- Henry Wadsworth Longfellow
Grown ravens are so skilful at interpreting the behaviour of other animals they usually get most of the prey.
By Manfred Dworschak
Ravens can toboggan, ride other animals and spy on their enemies. Their life as cadgers stealing prey from wolves, eagles and bears has made them outstandingly intelligent. But do ravens know what they're doing and why? Austrian biologists want to find out.
Those ravens! Their newest form of entertainment is wild boar rodeo. Biologist Mareike Stöwe swears she often sees ravens trotting through the enclosure on the backs of irritated wild boars. "Ravens like to make an impression," Stöwe says. The birds are always out to perform unusual tricks likely to impress their kin. Dangling head-down from a branch is another popular past-time of theirs.
Ravenologists always have something to laugh about. They're currently observing some common ravens (corvus corax) in large aviaries at the Konrad Lorenz Research Center in Grünau, Austria, where Stöwe works. The play instinct displayed by the birds is tremendous. In the winter time, they tumble down snowy hills. The especially courageous ones grab a boar by the tail and let themselves be towed through the snow on their backs, as if by a drag lift. And yet the questions explored in Grünau are serious. The most important one is: How intelligent are the animals really?
Their skills when it comes to tricking and cheating, for example, have not been thoroughly explored. Ravens are cunning enough to set up mock hiding places in order to distract their thievish fellows from their real food stores. They're generally very inventive when it comes to tricking those who would snatch away their food. But how much truth is there to reports according to which ravens play dead next to carcasses in order to simulate a case of food poisoning? Stöwe's colleague Thomas Bugnyar hesitates to believe such reports: "Many animals play dead in stressful stituations," he says. "But when it comes to ravens, everyone always suspects some hidden intention." Bugnyar has been examining numerous winged wise guys, partly in collaboration with US ravenologist Bernd Heinrich. They found that corvus corax has plenty of surprises in store even under strictly controlled laboratory conditions.
One of the trickiest challenges consists in making the raven sit on a bar with a piece of meat suspended vertically below it by a long string. What can the raven do to get at the dangling meal? There is only one solution: The raven has to use its beak to carefully pull the string a short way up. It then has to shape the string into a loop and place one talon on that loop. Then it has to pull the string up a little further and repeat the process. Done properly, the procedure allows the raven to gradually move the meat upward. Too much trouble for a bird? The smartest ravens examined in Grünau patiently considered the challenge and then pulled the meat up. They discovered the right procedure right away. It seems they mentally rehearsed the problem before getting started.
Quiet premeditation and reflection on possible action represent a pretty high level of intelligence - one that even primates struggle with sometimes. The researchers ran a second experiment to rule out errors: the ravens were shooed from the bar the moment they had seized on their dangling booty. Stupid birds would have held on to the meat even though it was still tied to the bar. But most ravens were happy to let it drop - they apparently knew it wouldn't be lost for good. The researchers were finally convinced following a further experiment in which the string was unfastened from the bar. Once the string had been unfastened, the birds flew away with the meat.
The ravens have now passed so many tests the researchers are wondering what purpose all this cleverness serves. Other birds get through life just fine with far less intelligence. A congenital program tells them how to build elaborate nests and sing cheerful songs. But intelligence is - from a biological view - labourious and costly. Those who think make mistakes. The question is, why has evolution made ravens so smart? Why don't they have the luxury of just doing the right thing automatically?
Ravenologist Heinrich has a simple answer: "The right thing hardly exists for ravens." The birds lead an extremely changeful life. In the wild, they live mostly off carrion slain by larger predators. Their survival depends on whether or not they reach the scene of the slaughter in time to grab whatever is there - usually in the presence of the predator. It's difficult to imagine a more precarious situation. Wolves, bears and foxes are easily angered when a pesky animal wants to eat their food. One casual snap of the jaws, and things are over for the raven. The bird needs to be able to assess just how far it can go at any moment. It always needs to consider the question of what is going through the minds of the larger beasts whose food it is stealing. In such dangerous situations, where nothing is predictable, a rigid program of behaviour would spell certain death. That's why ravens already acquire the art of flexibility during the first weeks of their lives. Barely fledged, they display an almost pathological curiosity for everything that can be pecked at and tweaked. Most importantly, they're driven by a powerful desire to annoy dangerous predators. The squabs repeatedly land near bears or wolves and approach them quietly from behind.
The art of flexibility
Bernd Heinrich has repeatedly seen young ravens tweaking the tail of a wolf and then immediately jumping away with wings flapping. That way, the birds gradually determine the point at which audacity becomes life-threatening - as well as acquiring a sense of how far the animal they are taunting can jump in one leap. Young ravens engage in these activities despite the fact that they are visibly terrified of the predators. "It's not a senseless game," Heinrich concludes, "but a congenital drive."
Grown ravens are already so skilful at interpreting the behaviour of other animals they usually get most of the prey. Up to 90% of the slain animal goes to the black-feathered nags. "So far, ravens have been grossly underestimated as carrion consumers," says Thomas Bugnyar. "They don't just grab the leftovers - they get almost everything."
It seems that from the point of view of the winged slyboots, large predators are little more than simpletons. Wherever such predators have slain their prey, ravens are quick to appear on the scene, as efficient as a clean-up squad. They don't even waste any time eating. Whatever they can get their beaks around is swiftly taken away and carefully hidden in the surrounding landscape - to be enjoyed later. That's why even large carcasses have often already been fully ransacked within half a day. Ravens especially like working with wolves. Sometimes they'll croak loudly to direct a pack of wolves to weak game they couldn't themselves attack. Researches who have examined this kind of cooperation even suspect wolves are driven to hunt in packs mainly because of the ravens. The predators are good sprinters and could theoretically slay game the size of deer alone or in pairs. But they would hardly get any meat for themselves during the feast that follows the slaying, due to the superior number of ravens.
When ravenologist Heinrich once experimentally placed two cow carcasses on the ground, he counted a total of 500 ravens that arrived to feast on the meat. "Some of them must have arrived from 100s of miles away," Heinrich says. "The restaurant was obviously well advertised." The mobile younger ravens, who ramble about in loose flocks, are in charge of spreading information. When they discover carrion, they immediately begin croaking to their companions, who rush to the scene. It's only that way that the young ravens stand a chance against their elders, life-long pairs of which rule over vast territories. The gangs of young ravens bet on the power of superior numbers, and the rulers of the local territory are often left out to dry. But companionship ends as soon as the prey has been secured. There is no sharing. Every animals puts as much meat aside for private consumption as possible. What is more, the smarter ones prefer letting others work for them, spying on their hiding places in order to plunder them as soon as an opportunity arises.
But few ravens are stupid enough to just let themselves be watched as they hide their prey. So the lurking thief must under no circumstances arouse the suspicion of its victim: "He has to restrain himself with iron discipline until the other has finally left," says Bugnyar. "That's an incredibly difficult thing for an animal to do." Ravens can do it. They have a long evolutionary process of espionage and counter-espionage to build on, in the course of which they became masters of deceit and problem-solving. They got better and better at guessing the intentions of others and concealing their own. "Ravens are cognitively equal to a 2-year-old child," says Bugnyar.
The birds are highly sophisticated when it comes to assessing their adversary's degree of knowledge and considering it for the purpose of their deeds and misdeeds. They won't attribute much brainpower to a wolf, for example. "When ravens discover a wolf burying a piece of meat, they watch him openly, "Bugnyar reports. "And when he leaves, they just dig it up." But when it comes to their conspecifics, who are prepared for such tricks, they act demonstratively uninvolved, grooming their feathers and stilting about as if bored. Bugnyar discovered that thieving ravens even spy on each other when searching for goods to steal. A raven will remember the other ravens that, together with it, witnessed the hiding of the meat. On top of that, it remembers which raven is likely to have seen which hiding place, and acts accordingly: hiding places not far from other ravens who may also be in the know are plundered first. The others can wait.
Such intricate strategic planning requires ravens to consider things from various points of view. It's almost a question of seeing through the eyes of others. That's a skill ravens share with the cleverest primates. But do ravens also know what they're doing and why? Or have they just developed an extraordinary cunningness in the struggle for food during the course of their evolution? In search of an answer to this question, Bugnyar next wants to investigate whether the birds also display intelligence in other contexts. At the research center in Grünau, things look very much as if that were the case. Ravens cultivate a rich social life, especially prior to sexual maturity, when they live in groups. And they deliberately forge alliances in their quest for certain positions. Ravens that have befriended each other stick together in conflict situations, and they don't steal from each other quite as unrestrainedly.
Ravenologist Stöwe has even observed gestures of consolation. When one raven has lost out in an argument, the other appeasingly runs its beak between the loser's feathers. "It's touching to see what gentleness these mighty beaks are capable of," says Stöwe. The biologist is a long way from growing bored of the lively birds with their searching spirit. "They look at everything we do so carefully," Stöwe says. "We're really the ones under observation."
The Common Raven (Corvus corax), also known as the Northern Raven, is a large all-black passerine bird in the crow family. Found across the northern hemisphere, it is the most widely distributed of all corvids. There are 8 known subspecies with little variation in appearance; however, recent research has demonstrated significant genetic differences between populations from different regions. It is one of the two largest corvids, alongside the Thick-billed Raven and is possibly the heaviest passerine bird. At maturity, the Common Raven is between 56 and 69 centimeters (22 to 27 inches) in length, with recorded weights ranging from 0.69 to 1.63 kilograms (1.5 to 3.6 pounds). Common Ravens typically live about 10 to 15 years in the wild, although lifespans of up to 40 years have been recorded. Young birds may travel in flocks, but later mate for life, with each mated pair defending a territory.
The Common Raven has coexisted with humans for 1000s of years, and in some areas has been so successful that it is considered a pest. Part of its success comes from its omnivorous diet; Common Ravens are extremely versatile and opportunistic in finding sources of nutrition, feeding on carrion, insects and food waste, in addition to cereal grains, berries, fruit and small animals. Some remarkable feats of problem-solving have been observed in the species, leading to the belief that it is highly intelligent. Over the centuries, it has been the subject of mythology, folklore, art and literature. In many indigenous cultures, including those of Scandinavia, ancient Ireland and Wales, Bhutan and the northwest coast of North America, the Common Raven has been revered as a spiritual figure or god.
Common Ravens have among the largest brains of any bird species. As with many other corvids, some remarkable feats of problem-solving have been observed anecdotally, leading to the belief that the birds have high intelligence. However, scientists remain unsure of the extent of their other cognitive processes, such as imitation and insight.
Common Ravens have been observed to manipulate others into doing work for them, such as by calling wolves and coyotes to the site of dead animals. The canines open the carcass, making it more accessible to the birds. They watch where other Common Ravens bury their food and remember the locations of each other's food caches, so they can steal from them. This type of theft occurs so regularly that they will fly extra distances from a food source in order to find better hiding places. They have also been observed pretending to make a cache without actually depositing food, presumably to confuse onlookers. They are also known to steal and cache shiny objects such as pebbles, pieces of metal, and golf balls. One theory is that they hoard them in order to impress other ravens. Other research indicates that juveniles are deeply curious about all new things, and that Common Ravens retain an attraction to bright, round objects based on their similarity to bird eggs. Mature birds lose their intense interest in the unusual, and become highly neophobic.
In recent years, biologists have begun to recognize that birds engage in play. Juvenile Common Ravens are among the most playful of bird species. They have been observed to slide down snowbanks, apparently purely for fun. They even engage in games with other species, such as playing catch-me-if-you-can with wolves and dogs. Common Ravens are known for spectacular acrobatic displays, such as flying in loops.
Source: en.wikipedia.org (much more to be found on the site)
Animal Behaviour: Quoth the Raven
Humans like to regard themselves as exceptional. Other animals do not have complex, syntactical languages. Nor do most of them appear to enjoy the same level of consciousness that people do. And many philosophers believe humans are the only species which understands that others have their own personal thoughts. That understanding is known in the trade as having a "theory of mind", and it is considered the gateway to such cherished human qualities as empathy and deception.
Biologists have learned to treat such assertions with caution. In particular, they have found evidence of theories of mind in a range of mammals, from gorillas to goats. But two recent studies suggest that even mammalian studies may be looking at the question too narrowly. Birds, it seems, can have theories of mind, too. In the Proceedings of the Royal Society, Bernd Heinrich and Thomas Bugnyar of the University of Vermont, in Burlington, describe a series of experiments they have carried out on ravens. They wanted to see how these birds, which are known to be (at least by avian standards) both clever and sociable, would respond to human gaze.
Response to gaze is reckoned to be a good measure of the development of theory of mind in human children. By about 18 months of age most children are able to follow the gaze of another person, and infer things about the gazer from it. Failure to develop this trick is an early symptom of autism, a syndrome whose main underlying feature is an inability to understand that other people have minds, too.
To test whether ravens could follow gaze, Dr Heinrich and Dr Bugnyar used six 6-month-old hand-reared ravens, and one 4-year-old. The birds were sat, one at a time, on a perch on one side of a room divided by a barrier. An experimenter sat about a metre in front of the barrier. The experimenter moved his head and eyes in a particular direction and gazed for 30 seconds before looking away. Sometimes he gazed up, sometimes to the part of the room where the bird sat, and sometimes to the part of the room hidden behind the barrier. The experiment was videotaped.
Dr Heinrich and Dr Bugnyar found that all the birds were able to follow the gaze of the experimenters, even beyond the barrier. In the latter case, the curious birds either jumped down from the perch and walked around the barrier to have a look or leapt on top of it and peered over. There was never anything there, but they were determined to see for themselves.
A suggestive result, but not, perhaps, a conclusive one. However, the second study, carried out by Dr Bugnyar when he was working at the University of Austria, and published last month in Animal Cognition, suggests that ravens may have mastered the art of deception too. In this case, the observation was serendipitous. Dr Bugnyar was conducting an experiment designed to see what ravens learn from each other while foraging. While doing so he noticed strange interactions between two males, Hugin, a subordinate bird, and Munin, a dominant one. The task was to work out which colour-coded film containers held some bits of cheese, then prise the containers open and eat the contents. The subordinate male was far better at this task than the dominant. However, he never managed to gulp down more than a few pieces of the reward before the dominant raven, Munin, was hustling him on his way. Clearly (and not unexpectedly) ravens are able to learn about food sources from one another. They are also able to bully each other to gain access to that food.
But then something unexpected happened. Hugin, the subordinate, tried a new strategy. As soon as Munin bullied him, he headed over to a set of empty containers, prised the lids off them enthusiastically, and pretended to eat. Munin followed, whereupon Hugin returned to the loaded containers and ate his fill. At first Dr Bugnyar could not believe what he was seeing. He was anxious about sharing his observation, for fear that no one would believe him. But Hugin, he is convinced, was clearly misleading Munin. As it happened, Munin was no dummy either. He soon grew wise to the tactic, and would not be led astray. He even stooped to trying to find the food rewards on his own! This made Hugin furious. "He got very angry", says Dr Bugnyar, "and started throwing things around." Perhaps ravens have something else in common with people - a hatred of being found out.
Source: www.economist.com 13 May 2004
Document Title: "Ravens, Corvus corax, follow gaze direction of humans around obstacles"
Journal Title: Proceedings - Royal Society of London. Biological sciences (Proc. - R. Soc. Lond., Biol. sci.) ISSN 0962-8452
Maybe Birdbrains Are in Fact Clever
by Gareth Huw Davies
The scene: a traffic light crossing on a university campus in Japan. Carrion crows and humans line up patiently, waiting for the traffic to halt. When the lights change, the birds hop in front of the cars and place walnuts, which they picked from the adjoining trees, on the road. After the lights turn green again, the birds fly away and vehicles drive over the nuts, cracking them open. Finally, when it's time to cross again, the crows join the pedestrians and pick up their meal.
If the cars miss the nuts, the birds sometimes hop back and put them somewhere else on the road. Or they sit on electricity wires and drop them in front of vehicles.
Biologists already knew the corvid family - it includes crows, ravens, rooks, magpies and jackdaws - to be among the smartest of all birds. But this remarkable piece of behaviour would seem to be a particularly acute demonstration of bird intelligence. The crows in Japan have only been cracking nuts this way since about 1990. They have since been seen doing it in California. Researchers believe they probably noticed cars driving over nuts fallen from a walnut tree overhanging a road. The crows already knew about dropping clams from a height on the seashore to break them open, but found this did not work for walnuts because of their soft green outer shell.
Other birds do this, although not with quite the same precision. In the Dardia Mountains of Greece, eagles can be seen carrying tortoises up to a great height and dropping them on to rocks below. The hapless Aeschylus (525 - 456 BC), a father of Greek tragic drama, is said to have met his end by this means. A seer predicted he would die when a house fell on him, so the wary scribe departed for the hillsides, well away from any dwellings, where he believed he was safe. He wasn't. An eagle is said to have mistaken Aeschylus' bald pate for a stone, and dropped the creature (in its "house") onto it.
Scientists have argued for decades over whether wild creatures, including birds, show genuine intelligence. Some still consider the human mind to be unique, with animals capable of only the simplest mental processes. But a new generation of scientists believe that creatures, including birds, can solve problems by insight and even learn by example, as human children do. Birds can even talk in a meaningful way.
Some birds show quite astonishing powers of recall. The Clarke's nutcracker, a type of North American crow, may have the animal world's keenest memory. It collects up to 30,000 pine seeds over 3 weeks in November, then carefully buries them for safe keeping across over an area of 200 square miles. Over the next 8 months, it succeeds in retrieving over 90% of them, even when they are covered in feet of snow.
On the Pacific island of New Caledonia, the crows demonstrate a tool-making, and tool using, capability comparable to Palaeolithic man's. Dr Gavin Hunt, a New Zealand biologist, spent 3 years observing the birds. He found that they used two different forms of hooked "tool" to pull grubs from deep within tree trunks.
Other birds and some primates have been seen to use objects to forage. But what is unusual here is that the crows also make their own tools. Using their beaks as scissors and snippers, they fashion hooks from twigs, and make barbed, serrated rakes or combs from stiff leathery leaves. And they don't throw the tools away after one use - they carry them from one foraging place to another.
Scientists are still debating what this behaviour means. Man's use of tools is considered a prime indication of his intelligence. Is this a skill acquired by chance? Did the crows acquire tool making skills by trial and error rather than planning? Or, in its ability to adapt and exploit an enormous range of resources and habitats, is the crow closer to humans than any other creature?
Dr Hunt, then of Massey University in New Zealand, said this of his research: "There are many intriguing questions that remain to be answered about crows' tool behaviour. Most important would be whether or not they mostly learn or genetically inherit the know-how to make and use tools. Without knowing that it is difficult to say anything about their intelligence, although one could guess that these crows have the capability to be as clever as crows in general."
The woodpecker finch, a bird of the Galapagos, is another consummate toolmaker. It will snap off a twig, trim it to size and use it to pry insects out of bark. In captivity, a cactus finch learnt how to do this by watching the woodpecker finch from its cage. The teacher helped the pupil by passing a ready-made spine across for the cactus finch to use.
Sometimes a bird species' very survival depends on its ability to learn fast. Birds need to recognise a cuckoo egg dumped in their own nest and either throw out the strange egg or desert the nest to start afresh. In Japan, the common cuckoo recently switched to a new, unsuspecting host on which to dump its eggs, the azure-winged magpie. The emerging cuckoo chicks ejected their foster siblings, and the magpie population dropped dramatically. Ten years on, the magpies started to fight back. They learnt to detect the "foreign" eggs. Within a few years, there was a 4-fold increase in its rejection of cuckoo eggs. The speed with which the magpie changed its behavior has astounded biologists.
Another sign of intelligence, thought to be absent in most non-human animals, is the ability to engage in complex, meaningful communication. The work of Professor Irene Pepperberg of the University of Arizona, Tucson, has now shown the general perception of parrots as mindless mimics to be incorrect. The captive African grey parrot Alex is one of a number of parrots and macaws now believed to have the intelligence and emotional make-up of a 3 to 4 year old child. Under the tutelage of Professor Pepperberg, he acquired a vocabulary of over 100 words. He could say the words for colours and shapes and, apparently, use them meaningfully. He has learned the labels for more than 35 different objects; he knows when to use "no," and phrases such as "come here", "I want X," and "Wanna go Y."
A bird's ability to understand, or speak, another bird's language can be very valuable. New Zealand saddlebacks, starling-like birds, occupy the same territory for years. They have distinct song "dialects" passed on through the generations. New territory vacancies are hard to find, so young males are always on the look-out for new widows into whose territory they can move. While they wander around the forest, they learn the different dialect songs, just as we might learn a language or develop a regional dialect. As soon as a territory-owning male dies, a new young male may move in to take over within 10 minutes. He will immediately start singing the dialect of the territory he is in.
Intelligence - if this is what scientists agree these birds possess - is not limited to the birds we always thought of as "bright." In recent experiments at Cardiff University in Britain, a pigeon identified subtle differences between abstract designs that even art students did not notice. It could even tell that a Picasso was not the same as a Monet. The experiment seems to show that pigeons can hold concepts, or ideas, in their heads. The visual concept for the pigeon is Picasso's painting style.
Some birds seem to indulge in "intelligent" play. The kea, a New Zealand parrot, has been filmed ripping (inedible) windscreen wipers off cars. Young keas, in a neat variation of ringing the doorbell and running away, are known to drop rocks on roofs to make people run outside.
Jack the jackdaw was raised by wildlife film producer John Downer. As soon as Jack was mature, he was released into the wild. However, he couldn't stay away. "One thing he is totally fascinated by is telephones," said Downer. "He knows how to hit the loudspeaker button and preset dial button. Once we came into the office to find him squawking down the telephone to the local travel agent." Jack also likes to fly down onto the mirror of the production car when he sees somebody going out. "He turns into the wind, gets his head down and surfs on the air current until we reach about 30 mph when he gives up. "Like all jackdaws, Jack shows great versatility and intelligence. Because he has to exploit a wide range of foods, he is investigating things all the time."
However, scientists believe it is not physical need that drives creatures to become smarter, but social necessity. The complexities of living together require a higher level of intelligence. Corvids and parrots, along with dolphins, chimps, and humans are all highly social - and smart - animals.
Some ravens certainly apply their intelligence for the good of the flock. In North America, they contact other ravens to tell them the location of a carcass. Ravens are specialised feeders on the carcasses of large mammals such as moose during the harsh winter months of North America. The birds roost together at night on a tree, arriving noisily from all directions shortly before sunset. The next morning, all the birds leave the roost as highly synchronised groups at dawn, giving a few noisy caws, followed by honking. They may all be flying off in the direction taken by a bird, which had discovered a carcass the previous day. This bird leads the others to his food store, apparently sharing his prize finding with the rest of the flock. Ravens share information about their findings of food carcasses because dead animals are patchily distributed and hard to find. Many eyes have a better chance of finding a carcass, and once one has been located, the information is pooled. Although the carcass now has to be shared between more individuals, the heavy snowfall and risk of mammal scavengers taking the kill mean that a single bird or a small group could not eat it all alone anyway. Some are even believed to solicit help with the carving, by tipping off other predators, such as wolves, about the meat so they will rip it open and make it more accessible to the ravens.
The African honeyguide lures badgers to bees nests, and feeds on the leftovers. To humans they offer their services as paid employees. They call and fly backwards and forward to draw local tribespeoples' attention to the location of honeycombs, and are then rewarded with a share of the takings for their trouble.
Of course, the bird world has its share of "bird brains." There are the birds that build three nests behind three holes under a flower pot, because they can't remember which is which, and birds that attack their own reflections. The Hawaiian goose is as innocent of danger as a baby crawling along the girder in an unfinished skyscraper. It would walk up to an introduced mongoose on Hawaii, and be attacked.
The level of intelligence among birds may vary. But no living bird is truly stupid. Each generation of birds that leaves the protection of its parents to become independent has the inborn genetic information that will help it to survive in the outside world and the skills that it has learned from its parents. They would never have met the challenge of evolution without some degree of native cunning. It's just that some have much more than others.
Source: www.pbs.org/lifeofbirds/brain date undenoted
-------- Original Message --------
I was reading about crows on the this page page because I recently came upon an interesting brood of them. I was in Nanaimo British Columbia, Canada on Vancouver Island, and along a road there were dozens of crows. At first I thought it was hailing, but it was the sound of walnuts hitting the road. The crows were dropping them in front of me and my friend so that we might step on them and break open. They also dropped them in front of any cars that came along.
Crow Feathers Nest with Cash
A crow has snatched half a million lire (NZ$540) from a Sicilian who was withdrawing money from an automated teller machine, but police are on the bird's trail. Bank staff confirmed the man's story. Police think the bird was trained to steal. A man with a pet crow was seen earlier. - DPA
Source: The Dominion Friday 26 January 2001
Crows Can Recognise Their Relatives
According to animal behaviorists Renee Robinette Ha and James Ha of the University of Washington, some crows are naturally honest and never steal food. Others steal about 65% of the time. Curiously, the bandits steal from relatives only if the relative allows it by dropping the food and walking away. For non-relatives, they will aggressively steal, snatching the food if they can.
The family Corvidae includes crows, ravens, jays and magpies. Ravens and magpies are believed to be able to count up to 7, and the crows of the Northwest drop shellfish onto hard surfaces to break them. The crows in New Caledonia make tools out of leaves and twigs to probe holes in trees for food - then store them in a "toolbox" to use at another time.
Crows as Clever as Great Apes, Study Says
by James Owen in London
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 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. 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. 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. The researchers also argue that such behaviour 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.
Source: news.nationalgeographic.com National Geographic News 9 December 2004
Rooks Use Cigarettes to Kill Bugs
Oddball birds are surprising British experts by using smouldering cigarette to kill parasites on their wings. The rooks are swooping on to the tracks at a Devon railway station and placing their wings over the smoke to fumigate them. Commuter Jeff Jones said told Britain's The Telegraph: "I noticed the rooks because they are not usually found in towns. They were generally flapping about when a chap flicked a cigarette butt on to the track. It was still [lit] and one of the rooks swooped down and picked up the butt with its beak. It then flew around and landed on the platform, dancing around with this smoking cigarette in its beak - it looked quite comical. But then it dropped the butt on the platform and pulled its wings over it, collecting the smoke. It seemed as if it were using the smoke to rid itself of perhaps ants or something similar. Five minutes later another rook - or perhaps the same one - swooped in when another cigarette was flicked away and repeated the whole thing."
Royal Society for the Protection of Birds spokesman Richard Archer said the birds must have learned cigarettes can be used to kill parasites. "You have to be careful attributing behaviour but it would seem fumigation is the most likely conclusion. Rooks are very intelligent," he said.
Source: news.com.au 4 June 2007
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