Meet the Owl that Fishes with Feces
Back in the early 2000s, ornithologist Doug Levey was teaching a course at the University of Florida when he had a weird idea about poop.
He and some of his students were on a field trip observing burrowing owls—a tiny, long-legged species that makes its home in underground burrows. If you’ve seen photos of burrowing owls, you know they’re pretty cute. If you’ve seen them in the wild, you know they’re also pretty weird. Unlike most of their cousins, burrowing owls are active during the daytime, and spend most of their day standing around the entrances of their burrows doing what seems to be a whole lot of nothing.
All of this standing around is done amid piles of dung, which the owls collect and arrange around their homes like bizarre lawn decorations. Cow dung. Horse dung. Dung from dogs, cats, antelope—you name it. If an animal shares territory with burrowing owls and poops, chances are the owls will take it home; they don’t seem to be picky about whose feces they’re collecting. But what do they do with all of it?
One of Levey’s students pointed out that there were lots of dung beetle parts scattered throughout the owls’ pellets, the masses of undigested food that some birds regurgitate. Levey quickly put two and two together. If you want to catch a dung beetle, he figured, you’d leave some dung out. Maybe the owls were using the poo piles as bait to lure in their prey.
To test the idea, Levey and his beetle-spotting student Scot Duncan cleared all the burrows of two different owl populations of their dung, pellets, and beetle pieces. Then they went back and scattered cow dung around half of them and left the other half alone. A few days later, they collected the regurgitated pellets and prey remains from all the burrows and kept them for analysis. Then they repeated the experiment, this time switching the burrows that got fresh dung and those that didn’t get any.
They found that the owls who had dung at their burrows ate much better than their dung-less neighbors; their pellets suggested that they consumed ten times as many beetles and six times as many different beetle species.
While it might look like the owls are standing around doing nothing, they’re really fishing for beetles with some unconventional bait.
It’s a fascinating bit of tool use, but no one can tell if the owls are consciously collecting the dung as bait, acting on instinct, or even bringing the dung home for another reason (like masking the odor of their eggs or chicks) and simply enjoying the beetle-luring effect as a bonus.