Crows are already known for their intelligence, but scientists have just discovered an entirely new talent: vocal counting.
In a recent study, researchers trained crows to produce specific numbers of caws (between one and four) in response to visual cues or sounds. This ability to count vocally has never been seen before in any animal besides humans.
“Counting out loud requires crows to not only understand numbers, but also to control their vocalizations in a specific way to communicate that number,” explains lead researcher Diana Liao, a neuroscientist at the University of Tübingen in Germany.
This is different from simply understanding numbers. It’s similar to how young children sometimes use random sounds to represent quantities before they learn actual number words. They might say “one, one, four” instead of “one, two, three.” The number of sounds is correct, but the order is mixed up.
Because crows have already shown they can grasp complex numerical concepts like zero, the researchers believed they were good candidates for studying more advanced number skills.
The crows were trained to caw a certain number of times (one to four) based on a symbol or sound they were shown. After each sequence of caws, they had to peck a target to signal they were finished.
All three crows successfully produced the correct number of caws most of the time, with occasional errors of one caw too many or too few. This mirrors how human toddlers count, using an imprecise system based on estimated numbers that’s planned out before they start vocalizing.
Interestingly, the first caw in a sequence seemed to be linked to the total number of caws that followed. Each caw also had unique sound features depending on its position in the sequence.
This vocal counting is particularly impressive because it’s harder for crows to produce deliberate vocalizations compared to simpler actions like pecking. It might even hint at a hidden form of communication among crows in the wild. For example, chickadees use more “dee” sounds in their calls when warning about larger predators.
The study suggests that crows can use a non-symbolic system for estimating numbers, similar to what humans and other animals possess. This ability might be an early step towards true counting, where numbers are linked to specific symbols and words.
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