The barn owl is generally nocturnal, though it can sometimes be seen hunting during the day, or the early evening. It hunts by flying slowly, then hovering over a patch of ground that it believes may conceal prey. It may also find a tree or post to use as a lookout point so that it can scan for food. When it spots its prey, the barn owl can swoop down to grab the creature using its talons. Barn owls hunt over open fields, generally within a range of a kilometre from their roosting or nesting site. As well as its good eyesight, the barn owl has extremely sensitive hearing, to help it hunt.
It is possible to determine the diet of a barn owl by studying its pellets, the parts of the prey that cannot be digested and are, instead, regurgitated. The preferred diet of a barn owl in the UK is small mammals such as voles and shrews. However, in other parts of the world, barn owls may eat a range of insects, amphibians and lizards. They will also eat smaller birds and bats.
Smaller prey is usually torn into chunks by the owl and then eaten completely, including bones and fur, whilst larger prey might be dismembered and unwanted parts discarded. Studies show that a barn owl will eat at least one vole a night, roughly 23% of its own bodyweight. Extra prey is sometimes stashed away at the roosting site to be eaten at times when food is scarce.
Barn owls consume huge numbers of the rodents that are often considered a pest by humans, making them one of the most economically valuable wild animals for farmers.