Burrowing owls commonly bring cattle or other mammal dung to the burrow and scatter it at the mouth and in the tunnel. Older explanations proposed that the dung masked the owls' scent from predators or served as nest lining.
A 2004 experiment by Levey and colleagues tested this directly. Dung was cleared from burrows, then replaced at some and withheld at others, and pellets and prey remains were compared. Burrows with dung yielded around ten times more dung beetles in the owls' diet, and no matching effect on predation was found. The interpretation is that the owls are baiting: dung attracts beetles, and the owl waits at the entrance.
The result has held up as one of the few clear cases of tool-like prey attraction in a bird, but it is a single system and some later work has questioned how general the effect is across populations. The owls also give a rasping call resembling a rattlesnake when threatened underground, a widely reported but less rigorously tested defence.