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Maybe “birdbrained” isn’t such an insult after all—crows, the ubiquitous city bird, can vocally count to four, according to recent research.
Curious creatures can not only count, but also match the number of calls they make when shown a digit, according to a new study led by a research team from the animal physiology laboratory of the University of Tübingen in Germany.
The way birds recognize and respond to numbers is similar to the process we humans use; both to learn to count as a toddler and to quickly recognize how many objects we are looking at. The findings, published Thursday in the journal Science, deepen our growing understanding of crow intelligence.
“Humans do not have a monopoly on skills like computational thinking, abstraction, tool manufacturing, and forward planning,” animal cognition expert Heather Williams said via email. “No one should be surprised that crows are ‘smart’.” Williams, a professor of biology at Williams College in Massachusetts, was not involved in the research.
In the animal kingdom, counting is not limited to crows. Chimpanzees were taught to count in numerical order and understand the value of numbers, just like young children. Some male frogs count the number of calls of rival males when trying to court their mates, and even increase that number by one when it is their turn to croak at a female. Scientists have even theorized that ants track their way to their colonies by counting their steps, but the method isn’t always accurate.
What this latest study shows is that crows, like young humans, can learn to associate numbers with values and count out loud accordingly.
Can crows count like little children?
Lead study author Diana Liao, a neurobiologist and senior researcher at the Tübingen laboratory, said the research was inspired by young children learning to count. Toddlers use number words to count the number of objects in front of them: If they see three toys in front of them, their counting may sound like “one, two, three” or “one, one, one.”
Maybe crows could do the same, Liao thought. It was also inspired by a study conducted in June 2005 on how mockingbirds adapt their alarm calls to the size of predators. The research found that the larger the predator’s wingspan or body length, the less likely it is to make the “dee” sound that mockingbirds use in their alarm call. The opposite was true for smaller predators; Songbirds will make more “dee” sounds when they encounter a smaller bird, which could be a greater threat to chickadees because they are more agile, Liao said.
The authors of the mockingbird study could not confirm whether small songbirds have control over the number of sounds they make or whether the number of sounds is an involuntary response. However, this possibility aroused Liao’s curiosity; Could crows, whose intelligence has been documented by decades of research, demonstrate control over their ability to produce a certain number of sounds by effectively “counting” like toddlers?
Crows planned the number of caws
Liao and his colleagues trained three carrion crows, a European species closely related to the American crow, over more than 160 sessions. During training, the birds had to learn the relationships between a series of visual and auditory cues, from 1 to 4, and produce the corresponding number of caw sounds. In the example the researchers provided, a visual cue might look like a bright blue number and the corresponding sound might be a half-second-long song of a drum.
The crows were expected to make the same number of caws as the number represented by the sign—three caws for the sign with the number 3—within 10 seconds of seeing and hearing the sign. When the birds stopped counting and cawing, they pecked at the “enter” button on the touch screen, offering cues to confirm they were done. If the birds had been counted correctly they would have received a reward.
It turned out that as the signs continued, the crows took longer to respond to each sign. Liao wrote that response times increase “as more vocalizations approach,” suggesting that crows plan the number of caws they will caw before opening their beaks.
Researchers were even able to tell how many songs the birds were planning to make by looking at the sound of their first song; These were subtle acoustic differences that showed the crows knew what number they were looking at and were synthesizing the information.
“They understand abstract numbers … and then they plan ahead by matching their behavior to fit that number,” Williams said.
Even the crows’ mistakes were somewhat advanced: If the crows cawed too much, stammered over the same number, or prematurely presented their beak responses, Liao and his researchers could detect where they were going from the sound of the initial call. wrong. These are “the kinds of mistakes people make,” Williams said.
We’re still learning how smart crows are
It was previously thought that birds and many other animals made only immediate decisions based on stimuli in their immediate environment; This theory was popularized by 20th-century animal behaviorist B.F. Skinner. But recent research by Liao and colleagues provides further evidence about crows’ ability to synthesize numbers to produce sounds, and suggests that this ability is under their control.
The study team’s findings are extremely specific but still important; Researcher Kevin McGowan of the Cornell Laboratory of Ornithology in Ithaca, New York, challenges the once-common belief that all animals are merely stimulus-response machines. We have been studying wild crows in their native habitat for more than two decades. McGowan was not involved in the study.
McGowan told CNN that the study shows that “crows are not simple, unthinking machines that just react to their environment, they actually think ahead and have the ability to communicate in a structured, pre-planned way.” “It’s a necessary precursor to having a language.”
Crow intelligence has been studied for decades. Scientists investigated how New Caledonian crows create their own composite tools to access food. Birds appear to set rules, according to a November 2013 study co-authored by Andreas Nieder, principal investigator of the University of Tübingen laboratory. Crow language has puzzled scientists for decades with its wide variety of tones and expressions, McGowan said.
Liao and colleagues’ study isn’t even the first to assess whether crows can be counted. Animal cognition expert Irene Pepperberg noted that this research began with Nicholas Thompson in 1968. Pepperberg, a research professor of psychological and brain sciences at Boston University, is best known for his work on an African gray parrot named Alex.
Thompson hypothesized that crows could count based on their caws, in which they controlled the duration and number in a given burst of sound. Crows’ counting abilities “appear to exceed the demands of survival on such abilities,” he wrote.
In September 2015, another study on the counting abilities of crows at the University of Tübingen trained the birds to recognize groups of dots and recorded the activity of neurons in the part of the crows’ brain that receives and makes sense of visual stimuli. The researchers noted that the crows’ neurons “ignore the size, shape, and arrangement of the dots and only infer their number,” the university said in a statement at the time.
“So crows’ brains can represent different quantities, and crows can quickly learn to match Arabic numerals to those quantities, something that humans often explicitly teach their children,” Williams said.
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