"Crows Can Count Out Loud - Scientists Are Stunned by This Study"

Crows Can Count Out Loud, Startling Study Reveals

This is the first time an animal other than humans has been seen performing the feat of vocal numeracy. A photograph of a carrion crow perched on a log

A photograph of a carrion crow perched on a log. (Image credit: CreativeNature_nl via Getty Images) Crows can count out loud, a surprising new study has revealed. They might even have the same counting skills as young children.

Researchers found that carrion crows (Corvus corone) can make a specific number of caws in response to what they see or hear. This lets them count out loud between one and four.

This discovery is the first time animals have been clearly shown to count by making distinct vocalizations. The researchers published their findings Thursday (May 23) in the journal Science.

"Making a specific number of vocalizations on purpose needs a complex mix of numerical skills and vocal control," the researchers wrote in the study. "Our results show that crows can flexibly and deliberately produce a set number of vocalizations using the 'approximate number system', a non-symbolic number estimation system shared by humans and animals."

Many studies have shown that animals, like honeybees, lions, frogs, and ants, have a natural sense of numbers. Another study found that black-capped chickadees (Poecile atricapillus) add more "dee" trills to their alarm calls to warn of bigger threats. But none of these provide enough proof that animals can count out loud like humans. For example, the chickadees might just be calling more because they are more stressed.

Related: Crows Outthink Monkeys, Can Grasp Recursive Patterns

To find stronger proof of vocal animal counting, the researchers studied carrion crows. These birds are a good choice because they have great vocal abilities and understand complex mathematical ideas like zero.

In the new study, the researchers presented three crows with random visual and auditory stimuli. The visual stimuli were Arabic numbers, and the auditory cues were different instrument sounds.

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Through trial and error, the birds learned that each cue matched a set number of caws between one and four. After making the caws (cawing four times for a sound or symbol linked to four caws, for example), the birds pecked the screen displaying them to signal they were done. If the crows gave the right number of caws, they got a treat.

Once trained, the counting crows gave accurate responses. They made the correct number of caws to the prompts more often than by chance. Even when the crows were wrong, their mistakes were usually between numbers close together (like three and four) rather than far apart (like one and four).

The researchers say that the birds' counting skills are like those of young children, who often count based on vocalizing numbers rather than using numbers themselves.

"This skill in crows is similar to toddlers' counting abilities before they learn to understand number words. It may be an evolutionary step towards true counting, where numbers are part of a symbol system," the scientists wrote.