
Crows, often depicted as harbingers of mystery in folklore, are now at the center of a revelation that may unravel the enigma of animal cognition. The term “birdbrained” might not be such an insult after all, as recent research reveals that crows can vocally count up to four.

These inquisitive urban birds can not only count but also match the number of calls they make when shown a numeral. This discovery, led by researchers from the University of Tübingen’s animal physiology lab in Germany, highlights a process similar to how humans learn to count and recognize quantities. Published in the journal Science, these findings enhance our understanding of crow intelligence.

“Humans do not have a monopoly on skills such as numerical thinking, abstraction, tool manufacture, and planning ahead,” said Heather Williams, an animal cognition expert and professor of biology at Williams College in Massachusetts. Although not involved in the recent study on crows, Williams emphasized that it’s unsurprising that crows are intelligent. In the animal kingdom, numerical abilities aren’t exclusive to crows.

Chimpanzees can count in numerical order and understand numeral values, similar to young children. Male frogs count competing calls to attract females, and scientists theorize that ants may retrace their paths by counting their steps, albeit imperfectly.

The research drew inspiration from the way toddlers learn to count, explained lead study author Diana Liao, a neurobiologist and senior researcher at the Tübingen lab. Toddlers use number words to count objects, so when they see three toys, their counting might sound like “one, two, three” or simply “one, one, one.”

Liao speculated that perhaps crows could exhibit similar behavior. Her inspiration stemmed from a study in June 2005, which observed chickadees adjusting their alarm calls based on a predator’s size.

Larger predators prompted fewer “dee” sounds, while smaller ones elicited more, indicating potential threats to chickadees. This observation intrigued Liao, who wondered if crows, known for their intelligence, could also have control over the number of sounds they produce.

Building on decades of research showcasing crow intelligence, Liao questioned whether they might possess the ability to effectively “count” through vocalization, akin to toddlers.

Over the course of more than 160 sessions, Liao and her colleagues trained three carrion crows, a European species closely related to the American crow. During these sessions, the birds learned associations between visual and auditory cues ranging from 1 to 4, and they had to produce the corresponding number of caws. For instance, a visual cue could be a bright blue numeral paired with the sound of a half-second drumroll.

The crows were tasked with matching the number of caws to the numeral shown, such as three caws for the numeral 3, within a 10-second timeframe after seeing and hearing the cue. Once they finished counting and cawing, they would peck at an “enter” key on a touchscreen to confirm their response. If their count was correct, they’d receive a treat.

Interestingly, the crows’ reaction times lengthened as the cues continued, indicating that they were planning their caws before vocalizing. This observation suggests that the crows were strategizing the number of caws they would produce in advance.

The researchers could discern the number of calls the birds intended to make based on subtle acoustic differences in their initial call. This indicated that the crows not only grasped the concept of abstract numbers but also planned their actions accordingly to match the given number. “They understand abstract numbers … and then plan ahead as they match their behavior to match that number,” explained Williams.

Even the errors made by the crows showed a level of sophistication. Whether they cawed one time too many, stumbled over the same number, or prematurely submitted their responses with their beak, Liao and her team could identify where the mistake occurred from the sound of the initial call. Williams noted that these errors resembled those made by humans, suggesting a high cognitive capacity in the crows’ numerical abilities.

According to McGowan, the study revealed that crows are not merely reactive creatures but rather possess forward-thinking abilities and structured communication skills, suggesting a fundamental prerequisite for language development.

This insight into crow intelligence adds to decades of research in the field. Studies on New Caledonian crows, for example, have shown these birds creating compound tools to obtain food, indicating a capacity for rule establishment as observed in a November 2013 study co-authored by Andreas Nieder, lead researcher at the University of Tübingen lab. The complexity of crow communication, characterized by diverse tones and expressions, has long puzzled scientists, highlighting the richness of crow language.
Relevant articles:
– These crows have counting skills previously only seen in people, Nature
– Crows can count much in the same way as human toddlers, study finds, cnn.com
– Crows can count much in the same way as human toddlers, study finds, CNN
– Crows can count out loud, startling study reveals, Live Science