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Maybe “bird brain” isn’t such an insult after all: Crows, the ubiquitous urban bird, can vocally count to four, according to the latest research.
Not only can curious creatures count, but they can also match the number of calls they make when shown a number, according to a new study led by a team of researchers at the Animal Physiology Laboratory at the University of Tübingen in Germany.
The way birds recognize and respond to numbers is similar to a process we humans use, both to learn to count as toddlers and to quickly recognize the number of objects we are looking at. The findings, published Thursday in the journal Science, deepen our growing understanding of crows’ intelligence.
“Humans do not have a monopoly on skills like numerical thinking, abstraction, tool making and planning,” Heather Williams, an expert in animal cognition, said by email. “No one should be surprised that crows are “intelligent.” Williams, a biology professor at Williams College in Massachusetts, was not involved in the study.
In the animal kingdom, counting is not limited to crows. Chimpanzees learned to count in numerical order and understand the value of numbers, just like young children. When attempting to woo mates, some male frogs count the number of calls from competing males to match or even increase that number when it is their turn to croak at a female. Scientists have even hypothesized that ants retrace their path to their colonies by counting their steps, although the method is not always precise.
This latest study showed that crows, like young humans, can learn to associate numbers with values – and count out loud accordingly.
The research was inspired by toddlers learning to count, said the study’s lead author, Diana Liao, a neurobiologist and principal investigator at the Tübingen lab. 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 might look like “one, two, three” or “one, one, one.”
Maybe crows could do the same, Liao thought. She also drew inspiration from a June 2005 study of chickadees adapting their alarm calls to the size of a predator. The greater the wingspan or body length of a predator, the less “dee” sounds the chickadees make during their alarm call, the study found. The opposite was true for smaller predators: Songbirds would use more “dee” sounds if they encountered a smaller bird, which could pose a greater threat to chickadees since they are more agile, Liao said .
The authors of the chickadee study could not confirm whether the small songbirds controlled the number of sounds they made or whether the number of sounds was an involuntary response. But the possibility piqued Liao’s curiosity: Could crows, whose intelligence has been well documented over decades of research, control their ability to produce a certain number of sounds, effectively “counting” as do crows? toddlers?
Liao and his colleagues trained three carrion crows, a European species closely related to the American crow, over the course of more than 160 sessions. During training, the birds had to learn the associations between a series of visual and auditory cues from 1 to 4 and produce the corresponding number of croaks. In the example the researchers provided, a visual cue might look like a bright blue number, and the corresponding audio might be the half-second song of a drum roll.
The crows had to perform the same number of croaks as the number represented by the signal –– three croaks for the signal with the number 3 –– within 10 seconds after seeing and hearing the signal. When the birds had stopped counting and cawing, they pecked at an “enter” key on the touch screen that presented their signals to confirm that they were finished. If the birds counted correctly, they would receive a treat.
It appeared that as the signals continued, the crows took longer to respond to each signal. Their reaction times increased as “more vocalizations were imminent,” Liao wrote, suggesting that the crows were anticipating how many croaks they were going to make before opening their beaks.
The researchers were even able to determine how many calls the birds planned to make by the way their first call was made — subtle acoustic differences that showed the crows knew how many digits they were looking at and had synthesized the information.
“They understand abstract numbers…and then plan ahead by tailoring their behavior to that number,” Williams said.
Even the mistakes the crows made were somewhat advanced: if the crows had cawed one too many times, stuttered on the same number, or submitted their responses with their beaks prematurely, Liao and his researchers could detect by the sound of the first call where they were going. . fake. These are “the same types of mistakes that humans make,” Williams said.
It was previously thought that birds and many other animals only made decisions on the spot, based on stimuli present in their immediate environment, a theory popularized by 20th-century animal behaviorist B.F. Skinner. But the latest research by Liao and colleagues provides more evidence about crows’ ability to synthesize numbers to produce sound and suggests that this skill is within their control.
The study team’s findings are very specific but nonetheless significant: They challenge the once-widespread belief that all animals are just stimulus-response machines, said Kevin McGowan, a researcher at the Cornell Lab of Ornithology in Ithaca, New York, who spent more time studying. more than two decades studying wild crows in their habitats. McGowan was not involved in the study.
The study, McGowan told CNN, demonstrated that “crows are not simple non-thinking machines that react to their environment – they actually think about the future and have the ability to communicate in a structured and planned. It’s sort of a necessary precursor to having a language.
The intelligence of crows has been studied for decades. Scientists have studied New Caledonian crows by creating their own compound tools to access food. Birds appear to make rules, according to a November 2013 study co-authored by Andreas Nieder, lead researcher at the University of Tübingen lab. Crow language has also baffled scientists for decades, with its widely varying tones and expressions, McGowan said.
The study by Liao and colleagues isn’t even the first to question whether crows can count. This research began with Nicholas Thompson in 1968, noted animal cognition expert Irene Pepperberg. A research professor of psychological and brain sciences at Boston University, Pepperberg is best known for her work with an African gray parrot named Alex.
Thompson hypothesized that crows could count based on their cawing, the duration and number of which the birds seemed to control within a given burst of sound. Crows’ counting abilities “appear to exceed the demands that survival places on such abilities,” he writes.
Another University of Tübingen study of crows’ counting abilities, carried out in September 2015, trained the birds to recognize groups of dots and recorded the activity of neurons in the part of the crows’ brain that receives and gives meaning to visual stimuli. The researchers found that ravens’ neurons “ignore the size, shape and arrangement of dots and only extract their number,” the university said in a statement at the time.
“So the crows’ brains can represent different quantities, and the crows can quickly learn to match Arabic numerals to these quantities – something that humans usually teach their children explicitly,” Williams said.