Ravens Remember Human Faces for 17 Years: A Remarkable Study

Mistreat a raven and you may gain a feathered enemy for life. A long-running US study reveals the extent of these birds’ intelligence and how long they can remember human faces. Its findings turn our understanding of the “animal brain” on its head.

How intelligent are ravens?

For centuries, ravens and crows have captured people’s imaginations. Legends portray them as harbingers of misfortune, while more recent research presents them as clever strategists. Scientists now place them among a kind of “bird elite”: they solve problems, use tools and maintain intricate social relationships.

Ravens recognise individual people, judge them to be dangerous or harmless, and retain that judgement for many years.

Researchers have long known that corvids can:

• Make tools and use them for specific purposes.
• Tell quantities apart and “count” in simple tasks.
• Plan hiding places and store food.
• Deceive other birds of their species to secure food.

The new research from Washington takes this further, revealing the strength of their long-term memory for faces and how such information spreads through a group.

The long-term raven study: It began with a mask

An unusual experiment began at the University of Washington in 2006. Behavioural researcher John Marzluff set out to discover whether ravens could recognise particular people as threats and remember them.

Wearing a distinctive rubber mask, he and his helpers captured seven ravens, placed rings on their legs and released them. For the birds, the mask was now associated with someone dangerous.

Over the following years, Marzluff and his team repeatedly walked around campus wearing the same mask. They caught no more birds; they simply walked about, sometimes carrying food.

From seven ravens to dozens

After a while, something remarkable happened. The original seven captured ravens were not the only birds to react. When the researcher crossed the grounds wearing the “enemy face”, 47 of the 53 ravens present loudly scolded him, even though most had never been caught.

The birds croaked and scolded in chorus, turning the campus into a raven courtroom.

The researchers concluded that ravens can pass information about dangerous people to other members of their species. They do more than remember a past threat themselves: they warn others too.

17 years of resentment: When the anger fades

For years, the researchers counted the ravens that raised the alarm when they saw the mask. The scolding peaked around 2013, when more birds than ever responded aggressively to the “enemy face”.

Only after that did the protests gradually decline. There are several reasons: birds die or move away, and younger birds take their place. As a result, part of the original chain of knowledge is naturally lost.

Then, in September 2023, a full 17 years after the experiment began, something striking happened. Marzluff walked across campus wearing the same mask without a single raven calling out in alarm or pursuing him.

For 17 years, then, the birds had stored the mask as a threat and carried that information through the population. Only after that did the collective resentment gradually die out.

The role of the “neutral” mask

The team used a second face mask to check that the birds were genuinely recognising a particular face, rather than simply fearing masks in general. This mask was considered “neutral”: its wearer behaved kindly, fed the birds and did not capture them.

When helpers wore the neutral mask, the ravens stayed calm or even approached curiously. The “dangerous” mask prompted angry calls and threatening flights, whereas the second mask produced no negative reaction.

Ravens do more than distinguish between a human being present or absent: they separate “dangerous” from “harmless” and remember the appearance associated with each.

Later, the team also asked volunteers to wear one of the masks at random, without telling them what each represented. Anyone wearing the “dangerous” mask found themselves surrounded by a chorus of raven cries. This confirmed that the birds were reacting to the face, not the individual underneath it.

Attacks on humans: When ravens take action

Reports from other countries suggest that ravens and crows put this knowledge to practical use in everyday life. In one affluent London neighbourhood, for example, residents repeatedly reported aerial attacks. Birds swooped down on particular people and pecked at their heads and shoulders.

One woman said she was attacked several times as soon as she got out of her car. Many locals temporarily preferred to stay indoors to avoid the attacks. Such incidents often occur after birds have had bad experiences, such as someone disturbing nests, frightening away young birds or striking at them.

Brilliant toolmakers with a tactical sense

Research into ravens extends beyond resentment and facial recognition. Numerous experiments demonstrate the flexibility of these birds’ thinking.

Examples from observations in the wild include:

• Ravens deliberately drop nuts onto busy roads, then wait for cars to crack the shells.
• They venture onto the road only when the pedestrian light is green, making use of the human traffic system.
• Some species carve hooks from twigs to pull hidden insects out of crevices.
• Others place suitable stones in water to raise the level in a container and reach food.

Such actions involve planning, imagination and learning across several steps – abilities once attributed almost exclusively to primates.

A complex society: Ravens do not live alone

Ravens do not lead a simple “bird life”. They form stable family groups in which older birds stay with young birds for a long time. Researchers have even observed behaviour resembling mourning ceremonies: when a group member dies, other birds gather near the carcass, call loudly and remain there for a while.

Their communication also appears remarkably nuanced. Different calls can signal food, enemies, rivals or mates. In some regions, researchers can even identify something like “dialects”, with vocal patterns varying from place to place.

Through their calls, ravens appear not only to warn of danger but also to form alliances and drive rivals away.

These social structures create a genuine network through which information circulates, including which bird had what experience with which person, and when.

Cultural learning: Knowledge passes through generations

One particularly fascinating possibility is that ravens have something akin to culture. Researchers do not mean art or music, but learned behaviours that spread through a population and persist across generations.

When a bird learns that a particular mask is dangerous, it passes on that knowledge through calls and reactions. Young birds adopt the behaviour even if they have never been captured or attacked. In this way, the “story” of a threat remains alive without every bird having to experience it first-hand.

Ways of dealing with food, tools or roosting sites can likewise become established within a group. Some tricks appear only in particular regions, while others seem to spread widely, much like traditions.

What treating ravens well means for people

Anyone who regularly encounters ravens in a garden, field or park should remember that these birds “register” behaviour very closely. Throw things at them, hit them or destroy their nest, and you may quickly end up on an internal blacklist – not just for one bird, but potentially for the whole group.

Respectful behaviour, by contrast, can ease the situation. People who do not harass ravens, reach for them or go near their nests are usually ignored or even remembered favourably. In some cases, the birds become so accustomed to particular people that they actively seek their company.

This knowledge also offers opportunities for urban planning and agriculture. Where ravens are regarded as a nuisance, targeted efforts can be made to reduce conflict rather than merely scare the birds away. Protecting nesting sites, setting clear feeding rules and providing quiet areas can all reduce tensions.

Ultimately, the data from 17 years of research show that ravens are not “minor characters” in our surroundings, but alert, thinking neighbours with good memories. Once you attract their attention, they remember you for a long time, whether the experience was good or bad.