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Maybe ‘birdbrained’ isn’t such an insult after all – crows, the ubiquitous urban bird, can vocally count to four, the latest research shows.
Not only can the curious creatures count, but they can also match the number of calls they make when presented with a number, according to a new study led by a team of researchers from 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 how many objects we are looking at. The findings, published Thursday in the journal Science, deepen our growing understanding of crow intelligence.
“Humans don’t have a monopoly on skills like numerical thinking, abstraction, tool making, and planning ahead,” animal knowledge 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 study.
In the animal kingdom, counting is not limited to crows. Chimpanzees, like young children, have learned to count in numerical order and understand the value of numbers. In an effort to court mates, some male frogs count the number of calls made by competing males to match or even increase that number when it is their turn to croak at a female. Scientists have even theorized that ants track their path back to their colonies by counting their steps, although the method is not always accurate.
What this latest research has shown is that crows, like young people, can learn to associate numbers with values –– and count out loud accordingly.
Can crows count like toddlers?
The research was inspired by toddlers learning to count, says lead study author Diana Liao, a neurobiologist and senior researcher in the Tübingen laboratory. Toddlers use number words to count the number of objects in front of them: when they see three toys in front of them, their counting may sound like “one, two, three” or “one, one, one.”
Maybe crows can do the same, Liao thought. She was also inspired by a June 2005 study about chickadees that tailor their alarm calls to the size of a predator. The larger a predator’s wingspan or body length, the fewer “dee” sounds the chickadees used in their alarm calls, the study found. The opposite was true for smaller predators — the songbirds would use more “die” sounds when encountering a smaller bird, which could pose a greater threat to chickadees because they are more agile, Liao said.
The authors of the tit study could not confirm whether the small songbirds had control over 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, demonstrate control over their ability to produce a set number of sounds, and effectively “count” the way toddlers do?
The crows planned their number of crows
Liao and her colleagues trained three carrion crows, a European species closely related to the American crow, for more than 160 sessions. During the training, the birds had to learn associations between a series of visual and auditory signals from 1 to 4 and produce the corresponding number of crows. In the example the researchers gave, a visual cue might look like a bright blue number, and the accompanying audio might be the half-second song of a drum roll.
The crows were expected to perform the same number of crows as the number represented by the cue within 10 seconds of seeing and hearing the cue – three crows for the cue with the number 3. If the birds had stopped counting and scratches, they pecked at an ‘enter’ key on the touchscreen that presented them with signals to confirm they were ready. If the birds counted correctly, they received a treat.
It seemed that as the signals continued, the crows took longer to respond to each signal. Their reaction speed increased as “more sounds were coming,” Liao wrote, suggesting that the crows had planned the number of crows they were going to make before opening their beaks.
The researchers could even tell by the way their first call sounded how many calls the birds were planning to make – subtle acoustic differences that showed the crows knew how many numbers they were looking at and had synthesized the information.
“They understand abstract numbers… and then plan ahead while tailoring their behavior to that number,” Williams said.
Even the mistakes the crows made were somewhat sophisticated: If the crows had cawed one too many times, stuttered over the same number, or submitted their answers prematurely with their beaks, Liao and her researchers could tell from the sound of the first call where they went. wrong. These are “the same types of mistakes people make,” Williams said.
We’re still learning how smart crows are
It was previously thought that birds and many other animals only made on-the-spot decisions based on stimuli in their immediate environment, a theory popularized by 20th-century animal behaviorist BF Skinner. But the latest research from Liao and her colleagues provides more evidence about crows’ ability to synthesize numbers to produce a sound, and suggests that this skill is within their control.
The research team’s findings are highly specific, but still significant. They challenge the once-common belief that all animals are just stimulus-response machines, says Kevin McGowan, a researcher at the Cornell Lab of Ornithology in Ithaca, New York, who has spent more than two decades studying wild crows in their habitat. McGowan was not involved in the investigation.
The study, McGowan told CNN, showed that “crows are not just simple, non-thinking machines that respond to their environment – they actually think ahead and have the ability to communicate in a structured, pre-planned way. It is a kind of necessary precursor to having a language.”
The intelligence of crows has been studied for decades. Scientists have studied New Caledonian crows that created their own composite tools to access food. The birds appear to establish rules, according to a November 2013 study co-authored by the lead researcher at the University of Tübingen laboratory, Andreas Nieder. The crow language has also puzzled scientists for decades, with its widely varying tones and expressions, McGowan said.
The research by Liao and her colleagues is not even the first to investigate whether crows can count. That research began in 1968 with Nicholas Thompson, noted animal science expert Irene Pepperberg. Pepperberg, a research professor of psychological and brain sciences at Boston University, is best known for her work with an African gray parrot named Alex.
Thompson hypothesized that crows could count based on their caws, the duration and number of which the birds seemed to control at a given burst of sound. The crows’ counting abilities “seem to exceed the demands that survival places on such skills,” he wrote.
Another University of Tübingen study on crows’ counting abilities from September 2015 trained the birds to recognize groupings of dots and recorded the activity of neurons in the part of the crows’ brain that receives and understands visual stimuli. The researchers found that the crows’ neurons “ignore the size, shape and arrangement of the dots and only extract their number,” the university said in a statement at the time.
“So crows’ brains can represent different quantities, and crows can quickly learn to associate Arabic numerals with those quantities — something people usually teach their children explicitly,” Williams said.
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