Birds might be listening to your conversations

Of all the crows in her lab, Sabrina Schalz’s favorite wasn’t the friendliest one, it was the one that was hardest to handle. When this particularly wily crow didn’t want to be grabbed for an experiment, it would perch with one foot on each of her hands, preventing Schalz from getting a secure, two-handed grip around the crow’s wings. “It was totally calm about it, and was like ‘yeah, whatcha gonna do now?’” recalls Schalz, a doctoral student in evolutionary ecology at Middlesex University in the U.K.

But that’s only the beginning of crows’ cleverness, says Schalz. Her recent research suggests that large-billed crows may be able to tell the difference between different human languages and pay closer attention to an unfamiliar human language over one they’ve heard before — almost as if they are trying to learn it. 

While crows are a long way from understanding human language, much less speaking it, their altered behavior in the presence of unfamiliar speech suggests they’ve learned to pay attention to it, perhaps as a protective mechanism, says Schalz. “It might be beneficial for crows to use speech to be aware of their surroundings,” explains Schalz, who discussed her research Oct. 29 at a virtual event titled “Avian Eavesdropping” that was presented by the London Natural History Society in the U.K. Schalz’s work on crow language discrimination is preliminary, and future work will need to be done to confirm her results.  

Yet, Schalz’s findings are remarkable, according to one other expert in the field. “I was really surprised by that finding,” says Kaeli Swift, an animal behaviorist at the University of Washington in Seattle, Washington who studies corvids, the family of birds that includes crows, jays, ravens, and others. “It is really interesting that [crows] would distinguish between human language.”

Scientists have long known that crows are highly intelligent. Crows create and use complex tools and even have funerals. But there’s a lot we still don’t understand about their behavior — including their own vocalizations. “We’re really good at parsing the communication of chickadees or vervet monkeys … but crows are still so mysterious,” says Swift.

Schalz’s work shows that, while we study crow communication, crows might be studying our language as well. The birds in her study were captured in Tokyo, Japan. In an outdoor cage, Schalz and her team played recordings of Japanese or Dutch sentences in short bursts and video-recorded the responses of seven crows over multiple trials. According to Schalz, the Japanese crows presented significantly more attentive behavior, and got closer to the speaker, when Dutch — the language they were less familiar with — was played. When Japanese was played, the crows showed less attentive behavior.

Vigilant crows, upon hearing Dutch, “will be looking around and kind of scanning the environment,” says Schalz, “they wouldn’t be looking down.”

Schalz and her team did not compare crow response to sounds other than recorded Dutch and Japanese in their experiment, and so these results don’t necessarily demonstrate that crows understand that Dutch is a human language. The results do, however, show that the birds might perceive Dutch as distinct from Japanese. 

Language discrimination has been tested in other animals, including Java sparrows, rats, tamarin monkeys, and even human babies. However, in those previous studies the subject animals were trained prior to testing — meaning they were exposed to both languages and given a reward for correct “answers.”Schalz’s study is the first of its kind to suggest language discrimination in non-human animals without prior training or rewards.

Now, Schalz has moved on to studying the carrion crows of London to try to replicate her findings in the wilds of local city parks and to try to determine why crows might benefit from listening in on their human co-habitants. Her leading hypothesis is that it’s a defense mechanism. In a densely populated urban environment, where humans and crows have lots of interaction, hearing human speech could be an indicator of potential danger.

That may be especially true in a city like Tokyo, which has a municipal crow capture program, aimed at reducing populations. The crows might pay attention to new languages more than familiar ones, not because overheard Japanese isn’t a warning of danger, but because — to a crow — unfamiliar languages could pose an unknown level of additional risk.

Crows “don’t just adapt to living in human environments, they really thrive,” says Swift. And a big part of that ability to thrive could be related to paying attention to people. Swift calls it “cultural co-evolution,” suggesting that overheard language may communicate not just general danger, but also possible reward. 

For example, Swift suggested that people speaking languages other than Japanese in Tokyo — namely, tourists — might be more likely to feed the crows they see because they consider them more of a novelty than a nuisance. Because of the possibility that people speaking different languages might act differently toward the Tokyo crows, Swift says, the birds may be motivated to find ways to tell tourists and locals apart in their search for food handouts. 

Schalz acknowledges that her research is in its early stages. “There’s so many question marks left,” she says, adding that she’s looking forward to expanding her studies to other animals in the urban environment. By scrutinizing the behavior of animals that thrive in cities, Schalz hopes we can learn more about how to improve urban conservation practices for all animals. “Hopefully at some point in the future, we can all coexist happily in the city together,” she says, eavesdropping and all.