Counting Crows: These Smart Birds Can Count Out Loud, According to Science

Some basic accounting is well within reach for these corvids.
'You've got three days to get me those walnuts, Marty. I know you know what that means.'
'You've got three days to get me those walnuts, Marty. I know you know what that means.' / Santiago Urquijo/Moment via Getty Images

Calling someone a “bird brain” isn’t really much of an insult. Birds possess extraordinary intelligence, and crows, in particular, have demonstrated keen abilities that continue to surprise researchers. The latest discovery: carrion crows can count out loud.

In a paper [PDF] published in the journal Science, researchers at the University of Tubingen in Germany recruited three Corvus corone subjects to analyze whether they could comprehend and vocalize numerical values in objects and sounds. The crows responded to these cues with anywhere from one to four “caws.” It’s a counting behavior similar to toddlers, in which the human children might single out three LEGO bricks by saying “one” three times, a kind of bridge approach to counting before they’re able to count to a total in their heads.

The crows were shown a numeral as well as a distinctive sound (like a guitar or drum roll) and were trained to respond to each with a set number of caws. Then, when shown the prompt again, the crows were expected to make the same number of sounds in order to get a reward. The idea was to get the crow to assess how many inflections were needed to reach their goal.

The crows performed the task successfully, but researchers were concerned the birds might just be cawing until their treat was delivered. So they added what amounted to a “submit” button, tasking the crows with pecking it after cawing as a way of saying they were done.

In the experiment, the crows demonstrated accuracy above the threshold of mere chance. When they got an answer wrong, it was typically within one caw, meaning the mistake was more likely a lapse in concentration rather than confusion.

But isn’t it possible the crows are simply mimicking the desired sound without truly understanding numbers? Researchers also observed a kind of tell: When more caws were expected, the crows hesitated before vocalizing, signaling they had to weigh the number needed.

In the past, crows have displayed abilities ranging from recognizing traffic lights to human faces. New Caledonian crows (Corvus moneduloides) can even craft simple tools—a tiny hook made from a twig that helps root out insects from crevices.

Proportionally, their brains are significantly larger than their interrogators’ at an average of 2.7 percent of its body weight compared to 1.9 percent for humans. So long as researchers continue studying crows, the more they’ll likely continue to surprise us.

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