New Study Suggests That Crows Can ‘Count’ Out Loud Up To Four

Published May 30, 2024
Updated May 31, 2024

The study used different cues to test crows' counting abilities, and the birds were rewarded with a treat for cawing the correct number of times.

Crows Counting Study

Aomorikuma/Wikimedia CommonsThe study observed carrion crows like the one seen here.

Crows often display their intelligence. They’re known to use tools, recognize human faces, and even hold grudges. Now, a new study suggests that they’re pretty good at counting, too.

These “counting crows” showed an ability to “count” up to four. What’s more, they demonstrated a level of thoughtfulness in their decision-making that researchers found particularly interesting.

Counting Crows: Inside The New Study

As described in a recent study published in the journal Science, researchers at the University of Tübingen in Germany arranged an experiment to see if crows understood the basic concept of counting.

“We were inspired by these studies of toddlers learning to count,” Diana Liao, an integrative biologist at the University of Tübingen and one of the authors of the study, told All That’s Interesting in an email. “They have yet to master true symbolic counting where there’s an exact cardinal representation of number. At this stage, they use number words instead as a verbal tally.”

Carrion Crow Cawing

Marie-Lan Taÿ Pamart/Wikimedia CommonsA carrion crow cawing. The study found that they could modulate the number of “caws” based on certain audio and visual cues.

She continued: “For example, when shown five apples and asked ‘how many apples are there,’ the child might not answer ‘five’ immediately but produce a sequence like ‘one-two-three-four-five’ or even ‘one-one-one-one-one’ where they are producing one counting word for each object as a sort of verbal tally. Is this ability to control the number of vocalizations shared with non-human animals?”

To find out, they trained three carrion crows (relatives of American crows) using a number of visual and audio cues. The audio cues were the sounds of instruments — for example a guitar chord for one caw, a drum roll for three caws — and the visual cues were Arabic numerals between one and four.

The crows were trained to produce one to four calls when they saw the number or heard the corresponding noise. Then, when they were done, they’d peck a key on the screen. And if they had cawed the correct number of times — e.g., three times for a drum roll or if they saw the number three on the screen — the crows were rewarded with a mealworm treat.

The three crows performed exceptionally well. Over thousands of trials, they demonstrated a 100 percent accuracy rate for counting to one, a roughly 60 percent accuracy rate for counting to two, a 50 percent accuracy rate for counting to three, and a 40 percent accuracy rate for counting to four.

“We found that crows could do it!” Liao told All That’s Interesting.

Three Crows

devra/Wikimedia CommonsThree crows in a tree.

She added: “We had an inkling that crows would be able to do this task because they have previously been shown to be numerically competent and also able to control the production of a single vocalization but it was still surprising how well they were able to accomplish this complex numerical vocal production task.”

The crows also demonstrated thoughtfulness. They seemed to take time to think before making a decision about how many times to caw, and they took more time to produce a long sequence of caws versus a short sequence.

The experiment demonstrates the intelligence of crows. But they aren’t the only animals who have shown a proficiency with counting.

Other Animals That Can Count

In 2005, a study found that chickadees changed their vocalizations based on the size of predators nearby. Known for their “dee” noises, the tiny birds used fewer “dees” when they saw large predators and more “dees” for small predators, which could pose more of a threat.

Chickadee

National Audubon SocietyChickadees have been observed changing the number of “dees” they vocalize depending on the size of the predator nearby, though it’s unknown if this is an involuntary response or not.

Other animals, like lions, frogs, bees, and ants, have also demonstrated a grasp of numbers. Even carrion crows have already been observed “counting” silently — when observing hunters, they can both identify human faces and tell how many have entered or exited a blind.

However, the new study has shown that these intelligent birds can also count out loud. When observing audio and visual clues, they showed surprising proficiency at cawing the correct number of times.

Power over numbers has long been thought to be a human trait — but this study goes to show that we aren’t the only ones who are proficient at counting.


After reading about the study that suggests crows can count to four, discover the stories of these surprisingly scary bird species. Or, learn about the great-eared nightjar, the stunning dragon-like bird found in India and Southeast Asia.

author
Kaleena Fraga
author
A staff writer for All That's Interesting, Kaleena Fraga has also had her work featured in The Washington Post and Gastro Obscura, and she published a book on the Seattle food scene for the Eat Like A Local series. She graduated from Oberlin College, where she earned a dual degree in American History and French.
editor
Cara Johnson
editor
A writer and editor based in Charleston, South Carolina and an assistant editor at All That's Interesting, Cara Johnson holds a B.A. in English and Creative Writing from Washington & Lee University and an M.A. in English from College of Charleston and has written for various publications in her six-year career.
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Fraga, Kaleena. "New Study Suggests That Crows Can ‘Count’ Out Loud Up To Four." AllThatsInteresting.com, May 30, 2024, https://allthatsinteresting.com/crows-counting-study. Accessed June 21, 2024.