Crows have a skill once thought to be uniquely human: recognizing geometrical shapes and spotting pattern differences.
A new study by researchers at the University of Tübingen reveals that carrion crows can identify geometric regularities without prior training. These findings were published in the journal Science Advances.
Led by Philipp Schmidbauer, Madita Hahn, and Andreas Nieder, the team tested whether crows could detect when one shape stood out.
Videographed at Piper’s Lagoon in Nanaimo.
These intelligent and resourceful birds have many unique characteristics, one of which is their vision. While most animals, including humans, rely on binocular vision (using both eyes simultaneously) for optimal depth perception and… pic.twitter.com/or6AbuOZTR— Brad Wildlife Photographer (@BradBlakley3) March 4, 2024
This skill, known as recognizing geometric regularity, is being able to identify when something doesn’t follow a visual pattern—like spotting a plastic star among plastic moons.
Scientists tested this ability in primates such as chimpanzees and bonobos in the past. Until now, no other creature besides humans has been known to possess this ability
Given how rare this skill is, the researchers cautiously approached this study. They designed a series of digital tests using computer screens.
The crows were shown sets of shapes and asked to peck the ones that looked different. A correct choice earned them a food reward.
The team picked carrion crows because earlier research indicates they are extremely intelligent. These birds have already demonstrated skills in problem-solving, memory, and even basic counting.
The results were clear from the start. Each bird quickly learned to select the shape that didn’t match. For example, they could easily pick out a star placed among rectangles.
The researchers introduced more subtle differences to explore the limits of their perception. In one test, a single box tilted slightly among identical upright boxes. Even then, the crows picked out the odd shape more often than chance would allow.
The surprising intelligence of crows demonstrated in an experiment showing they have a causal understanding level of a 5 to 7-year-old child. Full video: pic.twitter.com/LKqAmRjuoe
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Though accuracy dropped with difficult tasks, their performance stayed well above random guessing.
Further testing revealed even more impressive results. The birds could recognize visual elements such as right angles, parallel lines, and symmetrical shapes. These are essential features of geometry that humans typically learn in early education.
Most strikingly, the crows completed these tasks without any prior training to understand shapes. This suggests that their ability to detect regularity might be instinctive rather than learned.
According to the researchers, the findings offer strong evidence that this type of visual reasoning is not limited to humans. It may exist naturally in other intelligent species as well.
The study adds to a growing body of work showing that bird intelligence—particularly in species like crows and ravens—is more advanced than once believed.
