This Animal Can Hold a Grudge for Nearly Two Decades — And It Might Be Watching You

Crows, long recognized for their striking black plumage and sharp caws, have now been confirmed to possess extraordinary memories and a startling ability to hold grudges — even for nearly two decades. What an animal !

A groundbreaking study from the University of Washington has revealed that crows can remember individual human faces associated with negative experiences for up to 17 years, and can pass this information along to others in their group. This remarkable feat of memory highlights the bird’s surprising intelligence and social complexity.

The research, led by Professor John Marzluff, began in 2006 when he and his team donned a distinct, menacing mask while capturing and tagging seven crows on campus. The birds were released unharmed, but the mask left an impression. Over the years, researchers occasionally wore the same mask while walking through campus and feeding the local crow population. What began as wary scolding from a few crows quickly spread — at one point, nearly 90% of the crows they encountered responded aggressively.

This increase suggested that the crows not only remembered the threatening face but also communicated the danger to others, including offspring. Even birds that had never directly encountered the masked humans joined in the scolding, demonstrating a sophisticated form of social learning.

By 2013, the intensity of the crows’ response had peaked, but over the following decade, the birds’ aggressive behavior began to wane. By 2023, 17 years after the original experiment, not a single crow reacted during a masked walk, indicating the gradual fade of the memory over time.

To control for bias, researchers also used a “neutral” mask — modeled after former U.S. Vice President Dick Cheney — worn by individuals who treated the birds kindly. These wearers were largely ignored by the crows, further emphasizing the birds’ ability to distinguish between friend and foe.

Unwitting volunteers, unaware of the mask’s role in the study, were sometimes startled when wearing the “threat” mask, only to be met with angry caws and dive-bombing birds — powerful evidence of the birds’ long-term recognition skills.

This phenomenon isn’t limited to the laboratory. Similar incidents have occurred globally. In Dulwich, an upscale suburb in London, residents reported being targeted by crows, including dive-bombing attacks that forced some to stay indoors. One woman, Alison Frean, recounted being ambushed three times while exiting her car.

Crows have long impressed scientists with their intelligence. Known for tool use, problem-solving, and even counting, they’ve been observed cracking nuts by placing them in traffic lanes and waiting for cars to do the hard work. Some craft hooks from twigs to fish out food, and others use sticks to extract insects from tree bark.

Beyond tool use, crows exhibit complex social structures and emotional depth. They live in close-knit family units and appear to mourn their dead, sometimes gathering around fallen companions in what researchers describe as “funeral-like” behavior.

Perhaps most striking is their ability to engage in cultural transmission — the passing of knowledge from one generation to the next. When a crow learns to identify a threat, that knowledge doesn’t die with it. Instead, it spreads throughout the flock, equipping even the youngest members with crucial survival strategies.

These findings affirm crows as one of the most cognitively advanced bird species, capable of memory, emotion, learning, and community defense. It’s little wonder they’re regarded in many cultures as symbols of intelligence, vigilance, and adaptability.