How smart are the crows?

Recent experiments show that crows use logic to solve problems, and that some of their abilities are similar to and even surpass those of apes.

Bernd Heinrich and Thomas Bognier Scientific American

A hunter in the forests of North America sees a black crow (Corvus corax) roll over on its back and lie down with its feet in the air next to a beaver carcass lying on the snow. A biologist climbs a rock cliff to drown crow chicks, and their parents drop rocks on him from above. A lone raven makes a great noise near a distant cabin and thereby arouses a man standing near the cabin to look around and see a cougar about to pounce on him from hiding.

Each of these three men thought they knew what the ravens intended by their actions. The hunter thought that the crow was feigning death, as if it had been poisoned, to discourage other crows from competing with it for the meat of the beaver carcass. The biologist thought that the pair of crows tried, on purpose, to hit him with stones so he would go away. The man in the remote cabin thought the crow had warned him to save his life.

These hypotheses cannot be ignored, but most people who have become closely acquainted with crows will perhaps offer other, more reasonable explanations. Crows are probably the most game-loving of birds, and more than once, they seem to roll over on their backs, just for fun. Many times they furiously strike the substrate below their perch when a predator approaches their nest. And it is known that sometimes they lead animals to possible prey because they cannot overcome the prey by themselves, meaning that it is possible that the bird actually led the cougar to the man.

Is intelligence conscious?

There are plenty of stories about crows, and from many of them it can be concluded that they are very intelligent, but there is nothing in the stories to prove that their intelligence is conscious. Even behaviors, the sophistication behind which is much more visible to the eye, such as the habit of crows to cut a lump of fat into pieces so that they can carry them more easily, the way they precisely stack acorns so that they can fly with the whole stack, the way they arrange two donuts so that they can carry them both at once , and the simulated caches of food they prepare to deceive robbers, even all these do not prove that the crows are able to consciously consider possible actions and choose the most appropriate among them.
Based on the observations alone, it is impossible to rule out other explanations, such as instincts or mechanical learning of certain actions. Indeed, until the 90s, there was probably only one careful scientific study that indicated rational judgment in crows, of the kind that is taken for granted in humans.
This is a series of experiments published by Otto Kohler from the Zoological Institute of Königsberg (which no longer exists) in 1943. He showed that his 10-year-old pet crow, Yakov, could count to seven by training him to fetch food from a certain vessel among several vessels whose lids were each marked with a different number of dots.
Research from the last few years, most of which we both did, finally provides some conclusive evidence that crows are indeed intelligent, in the sense that they are able to use logic to solve problems.
And we found to our astonishment, that they can even distinguish between one crow and another. And in this sense they are similar to humans: we would not be able to build societies (except for those similar to societies of insects) without this ability.

Proof of problem solving
The crow is not the only bird to which it is customary to attribute wisdom. In the last 20 years there has been a flood of research that has revealed that some of their relatives in the crow family (which includes crows smaller than the black crow as well as the raven, the crow, and the jackdaw) have surprising and complex mental abilities. In some species it seems that these abilities do not fall short of the abilities of great apes, and even exceed them. Cicadas, for example, have a wonderful memory that stores thousands of locations of food caches - a task that most humans would struggle to accomplish.
Studies have shown that the New Caledonian crow (Corvus moneduloides) makes tools from parts of the leaves of the pandanus plant and uses them to extract larvae from tree crevices. But what was not known was the extent to which these extraordinary feats involve built-in blind programming, or memorization and memory (based on past trial and error), or thinking (choosing between options represented and weighed in the mind).
We therefore designed experiments designed to isolate the roles and relative importance of each of these possibilities. In the first experiment we presented individual crows with food hanging on a wire. To get the delicacy they had to lean down from the pole they were standing on, grab the string with their beak, pull the string up, place the loop of string they pulled on the pole, step on it with enough pressure that it wouldn't slip, then let go of the beak's grip on the string and repeat this series of actions six times or more.
We found that at least some of the adult birds examined the situation for a few minutes and then performed this multi-step process in one attempt that lasted only about 30 seconds, without devoting any preliminary efforts to trial and error. In a classic design of a laboratory experiment examining the behavior of animals, each step in the desired action is rewarded with food, while incorrect steps are punished with an electric shock.
The connections between the steps in the series are apparently created without the animal having to understand how each of them contributes to the final result. However, it is not possible that the birds we tested have already encountered this task in the wild, and therefore it is not possible that they learned to perform it in the past through trial and error. Therefore, the simplest explanation is that they imagined options and deduced what steps they should take.
However, success in the test required maturity. Young birds (one or two months after learning to fly) are unable to perform this complex operation. And a one-year-old bird needs an average of six minutes to solve the problem. In those six minutes, they openly try different options (for example, fly to the food, try to tear the string, peck it or pull and twist it).
שום שלב בסדרת משיכות החבל של העורבים לא תוגמל במזון. היה עליהם להשלים את כל הסדרה הארוכה כדי לקבל משהו לאכול. אפשר אולי לטעון שבצדו של כל שלב יש גמול "מנטלי" הפועל כחיזוק חיובי פשוט, כי עורב רואה את האוכל מתקרב אליו, בלי שהוא מבין שכל שלב בסדרה מקרב אותו אל מטרתו. אבל ההסבר הזה עומד על כרעי תרנגולת. אילו כל צעד היה נלמד בניסוי וטעייה היה צורך בהרבה מאוד ניסיונות, וללימוד הסדרה כולה היו נדרשים בוודאי חודשים של אימון. אבל לא כך היה. היה נראה שהציפורים יודעות מה הן עושות.

Did they understand?
However, it is impossible to know that they know unless they behave according to certain predictions. For example, if the crows knew what they were doing, they should also know what they had already done. They should have known, for example, that after raising the prize tied by the string, it was still attached to the pole. To check if they understood, we chased them off the pole after they brought up a piece of meat. If they dropped the meat, it means they knew it was attached to the pole. If they fly away with the meat (and cause it to tear from their beak), it means that they did not know. Most of them dropped the meat. On the other hand, if meat was placed on the pole to which a string was attached, which was not tied to the pole, the crows would always take it in their flight.
When you understand, there is no need, or almost no need, to conduct experiments. Learning by trial and error, on the other hand, does not require logic. We therefore asked to do another experiment to find out if the birds faced the challenge of pulling the meat through random movements that happened to have a reward on their side, but there was no logic behind them. This time we presented inexperienced birds with the same practical options, but in a situation that we hoped would make no sense to them. That is, the wire was placed so that they had to pull it down to bring the food up.
Even in this situation the crows showed interest in the food. They explored the device and poked and pulled the string and thus sometimes brought it a little closer to them. But they soon gave up, and no bird learned to get the food, although the same pull-step-release sequence that had previously enabled them to get the food easily could have made it possible again.
אנו סבורים אפוא שהמשיכה היישר למעלה נלמדה מהר ולעתים כמעט "מיד" רק מפני שנסמכה על היגיון. העורבים מסוגלים ככל הנראה לבחון פעולות בראשם ולדמיין את תוצאותיהן. נראה שלרוב בעלי החיים אין יכולת כזו, או שהיא קיימת אצלם במידה מועטה בלבד, ויש לכך סיבה הסתגלותית טובה.

What are the crows thinking about?
Studying the mental states of animals, who cannot tell us what they are thinking, is fraught with difficulties. And in practice we do not know, and perhaps we will not be able to know, what is going on in the mind of another animal, and perhaps not in the minds of other individuals of our species. But if we adopt the principle of Occam's razor and adopt the simplest explanation, according to the best scientific tradition, we can conclude that the experiments we conducted provide consistent confirmation of the hypothesis that crows use some mental representation that guides their actions.
The results of the tug-of-war experiments require the use of logic. And the tactics of robbery and guarding against it show that the crows remember the things that their competitors noticed and they estimate the expected threat as a result. They attribute to their competitors the ability to know, and combine this knowledge with the dominance status, to make strategic decisions about establishing food caches and emptying them.
Learning does exist, but it cannot explain all the observed behavior, because this behavior is manifested very quickly, almost immediately, without trial and error at all. We therefore hypothesize that the crows start with a game behavior pattern inherent in them from birth that produces the experience that is a necessary condition for learning. The learning may then be translated into conscious awareness, that is, the ability to use logic. Such an ability is useful in the highly unpredictable social environment of predators and competitors, and it can also be transferred and applied to any other state of affairs, such as pulling up food hanging on a string.

We don't know how unusual behavior like that of the crows is among animals.

About the authorsבֶּרְנְד היינריך (Heinrich) ותומס בוגניאר (Bugnyar) מוקסמים מכישוריהם השכליים של עורבים. הם חקרו ביחד את הציפורים כשבוגניאר היה עמית מחקר באוניברסיטת ורמונט שבה מכהן היינריך כפרופסור לביולוגיה מאז 1980. היינריך קיבל את תואר הדוקטור שלו באוניברסיטת קליפורניה בלוס אנג'לס ובילה 10 שנים במחלקה לאנטימולגיה באוניברסיטת קליפורניה בברקלי לפני שעבר לוורמונט. הוא חיבר כמה ספרים ידועים, ובהם "עורבים בחורף" (הוצאת סיימון ושוסטר, 1989) ו"שכלו של העורב (הוצאת הרפר-קולינס, 1999) שעומד לצאת שוב במהדורה חדשה בקיץ 2007. בוגניאר קיבל תואר דוקטור מאוניברסיטת וינה על מחקר שערך על עורבים בתחנת המחקר על שם קונרד לורנץ בגרונאו שבאוסטריה. היום הוא מרצה בבית הספר לפסיכולוגיה באוניברסיטת סנט אנדרוז שבסקוטלנד.

But we hypothesize that, although it is probably not rare, it is usually limited to certain types of tasks, because there is a rich variety of basic instincts and learning tendencies that are precisely adapted to the animal's living environment. However, in crows it may be more general than in most other animals.
We think so because we don't know of any game-loving bird like the crow that is exposed to such a wide variety of unexpected scenarios. Perhaps thanks to these tendencies, the crows became the bird whose natural distribution is the largest in the world, a bird that inhabits the same continents as humans, and integrates easily, like them, in many different habitats.

From the August-September issue of Scientific American Israel