Field notes / Social learning

How a whole crow flock can learn about a person

A famous Seattle-area experiment showed that American crows can learn from each other—which helps explain why a response to one person may spread well beyond the birds who first met them.

Featherence JournalOctober 20, 20266 minute read

The surprising result: crows that were never trapped later scolded a masked human associated with danger. Young crows also learned the response from their parents.

What did the researchers do?

At five sites near Seattle, researchers used a distinctive mask while trapping, banding, and releasing small groups of American crows. Later, they walked through the area wearing either the danger-associated mask or a neutral one and recorded the crows’ responses.

Some birds had directly experienced the capture. Others had not. When a crow scolded, other crows often joined the mobbing response, giving nearby birds social information about the person and the situation.

What spread through the community?

Over time, crows that had never been captured also responded to the danger-associated mask. The researchers found that young crows could distinguish the mask after their parents had learned to scold it. That is social learning: a young bird does not need its own capture experience to learn the cue.

At one site, scolding toward the mask doubled and spread at least 1.2 kilometres from where the original trapping began over a five-year period. That result is often paraphrased online as crows “teaching the whole city.” The actual study measured a specific response around several study sites—not a citywide count or a memory passed down unchanged for generations.

Primary studyCornell, Marzluff & Pecoraro (2012), “Social learning spreads knowledge about dangerous humans among American crows,” Proceedings of the Royal Society B. Read the paper.

Does this mean a whole murder will recognize a feeder?

It makes flock-level learning plausible, but the study was about danger. It does not show that a flock will automatically learn that a particular person is friendly, or that crows will arrive on command.

Research on food associations gives a complementary piece of the picture. Crows in a separate controlled experiment learned to distinguish faces associated with caretaking and food from faces associated with capture. In everyday life, a consistent person and a reliable resource can become part of a bird’s learned map. Which birds notice the routine—and whether they approach—depends on that place and those birds.

Related researchMarzluff et al. (2012), brain imaging of crows viewing familiar food-associated and threatening faces. Read the open-access paper.

Why the finding matters

Crows are social, observant neighbors. Their ability to learn from others means experiences can influence more than one individual. It also means the quality and consistency of human interactions matter: birds learn from what they see happen around them.

For someone building familiarity with a local flock, that is a reason to be patient and predictable. It is not a shortcut to recruiting a crowd. Let each bird choose how to respond and keep your routine calm.