Amazing abilities Crows recognize geometric shapes and parallel lines
Another piece in the puzzle of the amazing abilities of corvids: Crows are even able to recognize subtleties such as non-parallel lines in geometric figures.
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- Researchers at the University of Tübingen have been able to prove that crows can distinguish between different geometric shapes.
- And that the crows did not acquire their perception of regularity through learning during the experiments.
- The researchers' conclusion: Core knowledge about orders of magnitude and geometry is rooted in biological evolution
Five squares and a trapezoid in between - many children would find it difficult to recognize the different geometric shapes. Crows, however, manage this amazingly well, as a team led by Andreas Nieder from the University of Tübingen reports in the journal "Science Advances".
Nieder's team trained two ten and eleven-year-old crows (Corvus corone) to recognize the deviating shape on a screen among six shapes. Once the birds had recognized the "deviant", they pecked at this shape. They were given food as a reward.
Initially, the crows learned to recognize a clearly different image from a series of six images, for example a star among five circles. Once the crows had understood the principle, square shapes were shown in one half of the test runs without further training - for example five squares with an asymmetrical square in between.
That's not a square!
The birds spontaneously recognized the shapes, which differed due to geometric parameters such as asymmetry, more frequently than would be expected from the random statistical distribution. For example, one crow recognized a "wrong" square in almost 50 percent of cases, the other in almost 60 percent of cases. The value for purely random hits would be 16.7 percent. For more complex squares with more variable angles and less symmetry, the success rates were lower - an effect that also occurs in humans, as Nieder explains.
According to the researchers, a detailed analysis of their performance indicates that the crows did not acquire their perception of regularity through learning during the experiments, but that this ability was already present beforehand.
Crows, like humans, spontaneously recognize geometric regularity in visual shapes, the researchers conclude. This basic intuition illustrates that core knowledge of scale and geometry is rooted in biological evolution, the team explains.
And now: Three croaks please
Geometry is not the only strength of crows: although the dark birds are not celebrated for their singing, researchers are enthusiastic about their learning ability.
Experiments have shown that crows have a rudimentary ability to count - so if four hunters enter a wooded area, they can wait until all four have left. Nieder's team also showed that the animals can learn how often they should call: After being presented with certain picture symbols or sounds, they made one to four calls depending on the request and then pressed a final button.
In the wild, New Caledonian crows (Corvus moneduloides) use small branches to make tools. In experiments, they were presented with a water-filled Plexiglas cylinder in which food floated inaccessibly deep. The animals then threw things like stones into the water until they were able to grab the chunk. They preferred heavy objects and solid rather than hollow ones. In addition, they chose the water cylinder that was already filled to the highest level out of two.
In another study, researchers showed that the birds think through problems. They manage to use three different types of tools in succession to reach food - without having practised this beforehand.
I'll save this pebble for tomorrow
Counting, geometry, basic physics - already quite impressive? There's more: humans look into the future when making decisions - ravens (Corvus corax) do too. According to the motto: I can still use this later and I'll swap this for something better later.
This was shown by researchers in a study in which ravens had to store objects for hours that were used to obtain food - either directly as tools or as objects to be exchanged. One example was a stone of a certain size which, when thrown into the top of a special apparatus, caused a treat to fall out of the bottom.
Personally, you should bear in mind that crows have an incredibly good memory for nasty things that have happened to them. You shouldn't throw things at them or annoy them in any other way anyway, but even more so in view of possible revenge attacks. On the other hand, wild crows often come very close to friendly people they know and allow themselves to be fed.
