Crows really can count out loud, astonishing new research shows

It’s no secret that corvids are capable of astonishing feats of creative and intelligent thinking, but a newly discovered ability has us baffled.

A team of scientists has shown that crows can ‘count’ out loud and produce a specific and purposeful number of crows in response to visual and auditory cues. Although other animals, such as honey bees, have demonstrated the ability to understand numbers, this particular manifestation of numerical literacy has not yet been observed in any other non-human species.

“Deliberately producing a specific number of vocalizations requires an advanced combination of numerical skills and vocal control,” writes the team of researchers led by neuroscientist Diana Liao of the University of Tübingen in Germany.

“Whether this ability also exists in animals other than humans is still unknown. We show that crows can flexibly produce variable numbers of one to four vocalizations in response to arbitrary cues associated with numerical values.”

The ability to count out loud is different from understanding numbers. It requires not only that understanding, but also deliberate voice control for the purpose of communication. People are known to use speech to count numbers and communicate quantities, a skill that is learned young.

When toddlers are learning to count, it can take some time to learn the specific numbers associated with specific quantities. In the meantime, kids can sometimes use random numbers to make a vote count. Instead of counting “one, two, three,” they could say “one, one, four” or “three, ten, one.” The number of vocalizations is correct, but the words themselves are confused.

The biological origins of symbolic counting are unknown, but because crows are known to understand difficult numerical concepts such as zero, Liao and colleagues thought they were a good candidate for investigating more advanced number skills.

A diagram illustrating the experiment. (Liao et al., Science2024)

They conducted their research on three carrion crows (Corvus corone), which the researchers trained to produce a variable number of vocalizations, between one and four, after being shown a random symbol or audio signal. Once they had produced the required number of crows, the crows had to peck a target to indicate they were done.

The researchers found that all three crows were able to produce the correct number of crows in response to the signals, with the occasional error usually occurring as one crow too many or too few.

According to the researchers, this is similar to the way human toddlers count, using a non-symbolic approximation system that is planned in advance before the first vocalization.

Interestingly, the timing and sound of the first vocalization in a sequence was linked to the number of vocalizations made afterwards, and each vocalization in a sequence had acoustic characteristics specific to its place in that sequence.

This feat is especially impressive for crows, because intentional vocalizations are more difficult to produce and have longer reaction times than, for example, pecks or head movements.

It could indicate a previously unknown channel for bird communication in the wild. For example, chickadees produce a greater number of “dee” sounds in their alarm calls for larger predators.

“Our results demonstrate that crows can flexibly and purposefully produce an instructed number of vocalizations using the ‘approximate number system,’ a non-symbolic number estimation system shared by humans and animals,” the researchers write in their paper.

“This competence in crows also reflects toddlers’ enumeration skills before they learn to understand cardinal numbers and may therefore represent an evolutionary precursor to true counting, where numbers are part of a combinatorial symbol system.”

The research was published in Science.

Leave a Reply

Your email address will not be published. Required fields are marked *