How ravens and crows remember faces for 17 years

Many people see ravens and crows as sinister omens of misfortune. New research suggests that beneath their black feathers lies a memory capable of keeping humans in mind, quite literally, for many years.

Crows that remember faces

Carrion crows and their relatives rank among the most intelligent birds. They recognise themselves in mirrors, plan actions and solve complicated puzzles. Their dealings with humans are particularly striking: a person who harms them can remain in their memory for a very long time.

Ravens can remember hostile humans for up to 17 years and direct aggressive responses at those faces.

The finding comes from a long-term University of Washington study. Researchers followed a population of ravens on campus over many years, testing how well the birds remembered particular people.

The mask study: where it began

The experiment began in 2006, when a research team wearing a distinctive rubber face mask captured seven ravens, fitted them with rings and released them. For the birds, the message was clear: the person with that face meant stress and danger.

In the years that followed, researchers returned to walk across the campus at irregular intervals. Sometimes they wore the “dangerous” mask; at other times they wore no mask or chose a neutral one. They behaved peacefully and fed the birds.

Even the experts were surprised by the result. After a while, far more ravens scolded and circled the person wearing the dangerous mask than had originally been captured.

The number of birds responding aggressively rose at times to nearly fifty, from the original seven captured ravens.

The birds had apparently not only remembered the mask but also passed the information on to others of their kind.

Vengeful, but not forever

The longer-term picture was particularly intriguing. Researchers continued the experiment for many years, counting the ravens that raised the alarm on each walk involving a mask.

• 2006: The first seven ravens are caught by someone wearing the “enemy mask”.
• 2007–2012: The number of ravens responding aggressively steadily grows.
• 2013: Hostility reaches its peak, with the most alarm calls.
• From 2014: Attacks gradually decline.
• 2023: The mask prompts hardly any response.

For 17 years, the birds kept the dangerous face in their collective memory. Yet its significance appeared to diminish with each new generation. Eventually, holding a “grudge” apparently no longer pays off, at least when the mask has long ceased to represent a real threat.

Good mask, bad mask

The researchers also used a neutral mask to check that the birds really were associating faces with either “dangerous” or “harmless” behaviour. One example bore the face of a prominent politician, which initially meant nothing at all to the birds.

Wearing this neutral mask, helpers regularly fed the ravens without capturing or harassing them. There were no alarms or attacks, only curious looks and expectant croaking.

Ravens do not distinguish between humans simply as people; they judge particular faces as friendly or dangerous according to previous experience.

Later, the researchers recruited unsuspecting volunteers who knew neither the background nor whether they were wearing the “bad” or “good” mask. Anyone who happened to cross the campus in the enemy mask encountered an angry crowd of black birds overhead. With the neutral mask, everything remained peaceful.

When ravens frighten entire neighbourhoods

Reports from several cities show that this power of recall matters outside the laboratory too. In one London neighbourhood, some residents were at times almost too frightened to leave their homes. Ravens repeatedly targeted particular people as they got out of their cars or walked along a certain street.

Such attacks usually have a trigger: a nearby nest, young birds someone has unintentionally startled, or an earlier attack on a bird. Anyone who has become an “enemy” can feel the consequences clearly later on.

Tools, tricks and road traffic

Remembering faces is just one of the ravens’ remarkable abilities. For years, researchers have documented their use of tools and their strategic exploitation of their surroundings.

• They drop nuts onto busy roads, wait for cars to crack them open and collect the kernels when the traffic lights next turn red.
• They fashion small hooks from twigs to extract insects from crevices and tree bark.
• They hide food in several places while watching to see whether other ravens are observing them.

Birds that watch them feeding are often deliberately misled. Some pretend to bury something while the real food is hidden elsewhere. This “deception” requires the bird to have at least a rough understanding of what the other bird might see and know.

Family ties and “funerals”

Their social organisation is as notable as their cognitive abilities. Ravens often live in family groups, with young birds staying with their parents for a long time and helping to raise the next generation.

Observations suggest that they respond to dead members of their species. Groups gather, screech and watch both the dead bird and the surrounding area. To researchers, this looks like a combination of an alarm gathering and an exchange of information: what happened, and where is the danger?

Such “gatherings” could help the birds commit a specific danger to memory and recognise it later, much as they do in the mask experiment.

Their vocal communication is considerably more complex than simple croaking. Distinct dialects can be identified in some regions, and young ravens learn this “language” from older members of their group.

Knowledge passed from generation to generation

Ravens do more than store experiences individually: they actively share them. Once one bird identifies a particular person as a threat, others that have never had a direct encounter with that person soon react too. This apparently amounts to a form of social learning.

Researchers often call this “cultural transmission”: behaviour and knowledge of danger pass from one generation to the next. Similar effects are known in some monkey species and whales, but among birds they are comparatively rarely documented so clearly.

What this means for everyday life with ravens

The research carries a practical message for people. Anyone who annoys, chases or hurts ravens is dealing not just with one bird but with an entire network of eyes and beaks. A face remains in memory and can provoke negative reactions for years.

By contrast, someone who regularly behaves kindly, perhaps by feeding the birds or remaining calm, is more likely to make the “positive list”. Some birds deliberately seek out people they associate with food or safety.

Why these birds come so close to us

Ravens have lived alongside us for centuries, from city parks to motorway junctions. They understand our habits better than many people might like, using everything from bin collection times and commuter flows to leftover food to their advantage.

Their ability to remember faces and share experiences within the flock makes them silent chroniclers of our behaviour. Anyone walking to the station in the morning under the critical gaze of a raven family can be sure the birds know how often they have seen them before, and whether anything happened that they disliked.