CROWS COUNT

IN TEACHING MATH FOR ELEMENTARY TEACHERS, I oft shared the tale of a farmer plagued by crows feasting on his crops. The corvids weren’t fooled by a scarecrow.  And they’d scatter whenever he brought out a shotgun.

The farmer tried hiding in a nearby shed, only to find the birds would high-tail it when he came out armed. Then he tried confounding them by having his son accompany him entering the shed, followed by one of them exiting. The clever corbies weren’t deceived. 

Nor were they fooled when three people entered the shed and two left. Finally, the farmer assayed four people entering, then two leaving, then the third. 

This time, the crows apparently lost count. But, so impressed was he by their evident numerical skills that he decided to let them share his crops.

Celebrating Corvids. SimanaitisSays has previously celebrated “Corvid Lore.” And, this time around, AAAS Science, May 23, 2024, confirms the farmer’s tale in Virginia Morell’s “These Crows May Count in a Way Similar to Human Toddlers.”

Virginia Morell writes, “Carrion crows are known as “feathered apes” for good reason. They can recognize human faces and voices, open nuts by dropping them on highways for cars to crush, and count up to 30. When hunters stake them out, the black-plumaged birds know how many people—and which ones—have entered or left a blind. Now, scientists have discovered another remarkable skill.”

Image by Andreas Nieder from Science.

Morell continues, “Carrion crows can count out loud, effectively calling ‘one, two, three’ as they caw, researchers report today in Science. The work suggests the birds understand numbers and counting in a similar way to what humans do, making them the only other species known with this ability.”

The referenced paper is “Crows ‘Count’ the Number of Self-generated Vocalizations,” by Diana Liao et al., Science, May 23, 2024. From its Abstract: “Producing a specific number of vocalizations with purpose requires a sophisticated combination of numerical abilities and vocal control. Whether this capacity exists in animals other than humans is yet unknown. We show that crows can flexibly produce variable numbers of one to four vocalizations in response to arbitrary cues associated with numerical values.”

How Toddlers Do It. “In human ontogeny,” Liao and her colleagues say, “toddlers learning to verbally recite the counting list initially use number words not to represent cardinalities but as simple verbal tallies. When asked ‘how many?’ they produce as many vocalizations as there are objects (e.g., ‘one, one, one’ or ‘one, two, three’ for three).” 

More Than Chickadees. The researchers contrast this with some animals’ non-symbolic means of keeping track of quantities: “Similarly, some animal species convey information essential for survival through differing numbers of vocalizations. Chickadees, for example, scale the number of ‘dee’ notes in their alarm calls with the size of the predator, thereby conveying the magnitude of perceived threat. 

However, the researchers say, “We hypothesized that carrion crows, one of the few bird species that possess not only numerical competency but also volitional vocal control, can deliberately control the number of produced vocalizations.” 

That is, they’re doing something along the lines of a toddler’s “one, two, three.”

The Twa Corbies, 1919, by Arthur Rackham. Image from fromoldbooks.org.

Methodology. The researchers describe, “We trained three carrion crows (Corvus corone) to flexibly produce a variable number of one to four vocalizations in response to visual and auditory cues. After the crows initiated a trial, a vocalization cue (visual: colored Arabic numerals; auditory: distinct 500-ms sounds) instructed the production of a specific number of vocalizations.”

This and the following image from Liao et al., Science. 

Researchers continued, “The crows had to produce a target number of vocalizations and indicate the end of the vocal sequence by pecking at a confirmation stimulus (“enter key”). Correct trials in which the produced number of vocalizations matched the cued number were followed by a reward; more or fewer vocalizations than the target number were counted as errors and remained unrewarded.”

Bored Corvids? “Our previous analyses examined only correct trials, Liao and her colleagues recounted. “Next, we explored whether errors—when the crows produced more or fewer vocalizations than instructed—occurred because the motor plan was incorrect from the start or because the crows started out with a correct plan but ‘lost track’ while vocalizing.”

Indeed, the researchers’ analyses suggested “that crows started out correctly but ‘lost track’ during production.”

I wonder if the farmer’s corvid pals felt the same? ds

© Dennis Simanaitis, SimanaitisSays.com, 2024