After a three-hour walk through a British Columbia nature reserve, photographer Tony Austin had a stroke of luck when a murder of crows landed about 40 feet up the path from him.
As one bird began violently rolling in the dirt and gravel, Austin snapped photos, he tells Cathy Kearney at CBC News. A closer look at the photos later revealed that the crow wasn’t just getting dusty. Its body and wings had become covered in black ants.
"You don't often see crows that close. They were all strutting around," says Austin to NPR’s Bill Chappell. "Only the one was taking this dirt bath, which I thought was quite interesting. The others were walking around looking at it. They were certainly quite interested in what was going on, but they didn't seem alarmed."
The bird was flapping its wings on the ground, jumping into the foliage on the side of the path, then returning to the gravel and starting over, Austin tells NPR. When Austin shared the photos with a birding community on Facebook, a few fellow birders told him that the crow was anting, purposely covering itself with the insects.
"It seems that no one is really clear on why they do that, which is kind of mystifying, but exciting as well," says Austin to NPR.
More than 200 bird species show anting behavior, which involves fanning their wings out on the ground and picking up insects, usually ants. But capturing a photo of the behavior is rare, CBC reports. Ornithologists have known about anting since about the 1830s, and they have several theories about why birds might want to cover their feathers in the six-legged critters. Birds might use the ants to soothe their skin during molting, or they might be encouraging the ants to release formic acid, which keeps pests away.
Crows have a plethora of odd and impressive behaviors for researchers to investigate. They can solve puzzles, like one that requires displacing water in a glass tube by adding objects, and they can be trained to dispose of trash. On the macabre side, they often avoid or signal danger around crow corpses—but sometimes attempt to mate with them. Research published in September suggests that crows have a form of consciousness because they are capable of subjective experiences.
But the explanation behind anting remains elusive. A study published in 2015 in the journal Northwestern Naturalist suggested that a bird could begin anting for several different reasons, depending on its context.
"I don't think anyone has done a definitive study on anting behavior yet. I don't think we have the full answer yet,” says McGill University wildlife biologist David Bird to CBC. But at the end of the ordeal, “the ant also becomes something to eat.”