There's an unusual but known behavior among crows, that they gather around the bodies of their dead. A crow dead on the street or in a field will be surrounded by a few to a dozen or more crows, all seeming to contemplate their fallen comrade. The notion of crow funerals has been documented but not necessarily understood, so University of Washington biologists Kaeli Swift and John Marzluff decided to create experiments to find out what exactly is happening.

If you've ever read about experiments with crow behavior, you'll know the experiments often involve researchers wearing incredibly creepy masks. Crows learn to recognize individual faces and teach their offspring who (or what) to be concerned about. And because crows have a long memory, a researcher could be disliked by local crows for decades. To avoid a long-running feud, the Washington research volunteers donned masks. They also wore signs that explained that the exercise was all part of a crow study. (The signs were for humans, of course, not the crows, but not a bad idea: Along with the creepy masks, researchers carried around a dead crow. The things researchers do for science...)

New York Times reports:

"It begins with a woman named Kaeli N. Swift sprinkling peanuts and cheese puffs on the ground. Crows swoop in to feed on the snacks. While Swift observes the birds from a distance, notebook in hand, another person walks up to the birds, wearing a latex mask and a sign that reads “UW CROW STUDY.” In the accomplice’s hands is a taxidermied crow, presented like a tray of hors d’oeuvres."

Swift watches what happens when a volunteer approachs the crows. When someone is carrying the crow, the person is mobbed almost every time. The crows will continue to scold that figure for as long as six weeks later, even if the person is empty-handed. The crows also take a longer time to approach the food source again after seeing a person with a dead crow in that area.

On the other hand, if a masked volunteer is carrying a taxidermied pigeon, the figure will be mobbed only about 40 percent of the time by the crows, and the crows won't really hesitate to return to the food source after the person leaves.

The conclusion? The sight of a dead crow leaves a lasting impression on living crows.

Swift and Marzluff suggest that the reason crows pay such close attention is because it's a learning opportunity for survival, a chance to know which individual humans, animals or situation are dangerous. Gathering together may be a way to share this information with the group, protecting the remaining members of the flock.

It's clear crows know how to recognize a friend versus an enemy. In one famous recent example, crows began bringing gifts to a little girl who regularly fed them, whereas they continue to scold people they recognize have done them harm and teach other crows to scold the same individuals. What have been called "crow funerals" may be more aptly considered crow study sessions, where they learn lessons about what caused a fellow crow harm so they can avoid a similar fate.

The research is particularly compelling because only a small handful of species are known to pay attention to their dead. “It’s pretty consistently animals that live in social groups and are known for having more advanced cognitive skills,” Swift told the New York Times. “It’s amazing to think a crow — a bird — is doing something like this that so few other animals are doing that we know.”

The study is published in the recent issue of Animal Behaviour.

Jaymi Heimbuch ( @jaymiheimbuch ) focuses on wildlife conservation and animal news from her home base in San Francisco.