Many who have heard the melancholy cry of the mourning dove might wonder: Do birds grieve for their loved ones?
For this Saturday’s Weird Animal Question of the Week Emilie Bouef commented via Facebook: "I heard that ravens do some kind of funeral when one of them dies. I’d love to know more about this."
Calling to each other, gathering around, and paying special attention to a fallen comrade is common among the highly intelligent corvids, a group of birds that includes crows, jays, magpies, and ravens, says Kaeli Swift, a Ph.D student in environmental science at the University of Washington. (See "Are Crows Smarter Than Children?")
But it doesn't necessarily mean the birds are mourning for their lost buddy. Rather, they're likely trying to find out if there's a threat where the death occurred, so they can avoid it in the future.
Man Behind the Mask
At the start of her two-year experiment, Swift put out food at over a hundred sites where in Washington State, which attracted breeding and nesting crows.
Swift then had about 25 human volunteers don masks and asked them to stand near the food for 30 minutes, in clear view of the crows. The masks obscured the volunteers' facial expressions, as well as allowed a rotating cast of people to be involved in the experiment.
Each volunteer was either holding a dead crow, standing near a dead red-tailed hawk—a crow predator—or standing near a dead red-tailed hawk holding the dead crow. (All the birds used in the experiment were taxidermied.) As the control variable in the experiment—the element that's unchanged—there was either no volunteer present or one who was empty-handed.
Almost universally, the crows responded to seeing the people and dead birds by “scolding”—or putting out an alert call to other crows. Of the four situations, the hawk-and-dead-crow combination provoked the most reaction. The crows did not react to the empty-handed control volunteer. (See National Geographic’s photos of brainy animals.)
The volunteers to whom the crows reacted returned to the site periodically for six weeks, though they went empty-handed. Even so, the crows continued to scold that person the entire length of the experiment, and were more wary of the area for several days—suggesting they consider people handling dead crows a threat.
In a second experiment, Swift also found the crows had a much milder response to a masked person holding a taxidermied pigeon, indicating "that crows are more sensitive to dead crows than to other kinds of birds,” Swift says.
Overall, the research showed that just the inference of danger was enough to make the crows skeptical of people. (Discover how a crow solved a challenge from Aesop's fables.)
Forget You Not
Other experiments have revealed that American crows never forget a (human) face—even for nine-and-a-half years and counting, John Marzluff, a biologist at the University of Washington and co-author on the new study, (Also see "Clever New Caledonian Crows Use One Tool to Acquire Another.)
Such a skill is beneficial for these long-lived, social birds, partly because they have to deal with unpredictable people.
If you're a crow "some people will kill you, other people will feed you," and that can switch if, say, a bird lover moves out of a house and someone less bird friendly moves in, Marzluff notes.
So crows have to be "nimble" in their interactions with us—and the study supports the idea "that these crows do pay attention" to individual people.
In previous research, Marzluff and his team have imaged brains of American crows and shown that the hippocampus—a part of the brain associated with learning and memory —is activated by the sight of a person holding a dead crow..
"These associations may be renewed" if the threat is seen again, he says.
For instance, in 2008 Marzluff had researchers in caveman masks capture crows while others in a control mask—Dick Cheney—let the birds be. Afterward the birds ignored the harmless Cheneys but scolded and chased the cavemen, and did so for years.
Poor birds! Probably thought they could trust a Crow-Magnon.
Weird Animal Question of the Week answers your questions every Saturday. If you have a question about the weird and wild animal world, tweet me, leave me a note or photo in the comments below, or find me on Facebook.