We've been feeding a small family of four crows (mated pair and their two year old kids) for several years. Last week two days in a row they left these gifts, pull tabs threaded onto pine twigs. This isn't only generous, it's creative, it's art.

My mind is blown. pic.twitter.com/tT5ORZ3AHL — Stuart Dahlquist (@StuartDahlquist) March 24, 2019

Stuart Dahlquist had been feeding a family of American Crows in his backyard for more than four years before the crows gave him something back. At least, in his view.

One recent morning in March, Dahlquist stepped outside his home northeast of Seattle and noticed a short pine sprig with a soda tab threaded through the end. It was positioned right by his backdoor, exactly where he leaves an offering of dried cat food each day. The next day he found a second sprig identical to the first in the same spot. He and his wife walked the neighborhood, but couldn’t find another explanation for the strange objects. The crows, they reasoned, must have looped the tags onto the pine stems and left them behind for their human benefactors to find.

Dahlquist, a musician and handyman who runs a pet door installation business, shared a picture of the twigs on Twitter. “This isn’t only generous, it’s creative, it’s art,” he wrote. It went viral, with more than 9,000 retweets and 33,000 likes.

But is it truly possible that crows crafted these objects and purposefully left them for Dahlquist to find?

“It’s definitely not a behavior that I’ve ever seen before,” says Kaeli Swift, an animal behaviorist who studies corvids at the University of Washington. “But it wouldn’t necessarily surprise me if a crow did it.”

Crows, as members of the corvid family, are highly intelligent creatures that make tools, recognize individual humans, and learn from one another. Wild crows are not known to create or display art. But they do occasionally leave behind objects like keys, lost earrings, bones, or rocks, for the people who feed them, a behavior that John Marzluff, conservation ecologist and Swift’s colleague at the University of Washington, calls “gifting.”

Marzluff first learned about gifting in the early 2000s when collecting stories for a new book about crow intelligence. A man who had fed crows in his backyard for years told Marzluff that, one day, he found a candy heart perched on his bird feeder. Although skeptical at first, Marzluff couldn’t find another reasonable explanation for the heart’s appearance other than the crow had left it there.

Not everyone who feeds crows receives strange objects, but there is enough anecdotal evidence that Marzluff has no doubt it happens. The behavior isn’t well studied, but limited evidence suggests corvids act differently around people they are familiar with. For example, a 2014 study from the Konrad Lorenz Institute in Austria showed ravens and crows were more motivated to exchange objects with human experimenters they knew, rather than humans they didn’t.

Learn more about the behaviors of crows, ravens, and other corvids with our free Audubon bird guide app.

What scientists can’t know, however, is why the birds leave behind these objects. “In animal behavior that is always the sticky point— intention — because we cannot ask them,” says Jennifer Campbell-Smith, a behavioral ecologist who earned her PhD studying crows at Binghamton University.

Humans are quick to assume that the crows leave behind objects as acts of gratitude. After all, people often find “gifts” where they feed the corvids, implying some kind of reciprocity. But when we assume gratitude, we project human emotions onto animals, says Swift.

Rather, gifting behavior could easily start out as an accident, she says. Curious crows will often fly off with an object, then lose interest and leave it behind. If the crow happened to leave an object where humans put out food, those humans might get excited and lay out even more food. The crow would learn that leaving behind random objects means a bigger meal and could teach other crows in the family to do the same. “If you’ve ever trained a dog, you know food is an amazing motivator to reinforce behavior,” Swift says.

Creating a “gift” by purposefully threading metal soda tabs onto twigs would take this behavior a step beyond what these scientists have seen before. But Marzluff and Campbell-Smith also would not rule out that Dahlquist’s crows had made the soda-tab twigs. “I am very skeptical of random internet sources, but knowing these birds and how intelligent they are, I wouldn’t be shocked,” says Campbell-Smith.

We may not know why crows do what they do, but that doesn’t make these creatures any less fascinating, says Swift. “It’s still an amazing example of the way crows are really watching us and are mindful of us—and, in their own way, [are] data mining for the best way to manipulate us," she says.

For his part, Dahlquist plans to continue feeding the crows and is considering getting a tattoo of the pine sprigs. He wishes he could tell the crows about his viral post. But the crows are still crows, and you can’t eat a tweet.