At ScienceAlert, Jess Cockerill reports that crows are the first non-human animal identified as able to recognize geometric shapes:

They can detect the ‘odd one out’ in a set of geometric shapes, and have an affinity for geometric regularity – shapes with consistent features, like squares, as opposed to irregular ones, like rhombuses.

“Crows Are So Smart They Can Identify Geometric Shapes, Study Finds,” April 22, 2025

How did researchers determine this?

[Andreas] Nieder and his colleagues from the University of Tübingen in Germany worked with two male carrion crows (Corvus corone), aged 11 and 10 years old, for the experiment.

The crows were trained to detect a single outlier shape that didn’t match the five otherwise identical two-dimensional shapes displayed on a computer screen. To demonstrate which shape they determined to be the ‘intruder’, the crows pecked on its on-screen position…

The crows found it easier to detect an outlier among four-sided shapes with regular features, like the even length of sides in a square, or the consistent 90-degree angles of a rectangle. The more regular the shape’s angles and sides, the more accurate ‘intruder’ detections the crows made. Identify Geometric Shapes,

From the open-access study:

The crows exhibited a geometric regularity effect, showing better performance with shapes featuring right angles, parallel lines, or symmetry over more irregular shapes. This performance advantage did not require learning. Our findings suggest that geometric intuitions are not specific to humans but are deeply rooted in biological evolution.

Philipp Schmidbauer et al. ,Crows recognize geometric regularity. Sci. Adv.11,eadt3718(2025).DOI:10.1126/sciadv.adt3718

Are crows really unique?

Detecting shapes, especially from overhead, could benefit many flighted birds. Thus some of us suspect that discovering this talent in crows may be due to the fact that crows are so often studied rather than that they are unique in detecting shapes.

Calling it a “geometric intuition” is a bit of a stretch though. Let’s save that for Pythagoras (ca. 570 to ca. 490 BC) and his famous theorem.

Here’s a less scientific example of a crow’s talents in shape detection: