Surrey

It hunts by flying low and slowly over an area of open ground, hovering over spots that conceal potential prey. They may also use fence posts or other lookouts to ambush prey. The Barn Owl feeds primarily on small vertebrates, particularly rodents. Studies have shown that an individual Barn Owl may eat one or more rodents per night; a nesting pair and their young can eat more than 1,000 rodents per year. Locally superabundant rodent species in the weight class of several grams per individual usually make up the single largest proportion of prey, no matter whether they are Muridae, Cricetidae, or Geomyidae (pocket gophers). Such animals probably make up at least three-quarters of the biomass eaten by each and every T. alba, except in some island populations. In Ireland, the accidental introduction of the Bank Vole in the 1950s has led to a major shift in the Barn Owl's diet: where their ranges overlap the vole is now by far the largest prey item.

The diet is supplemented with local small vertebrate and large invertebrate life. A Barn Owl will eat anything it can subdue and that is more than a beakful, from small invertebrates weighing less than 0.05 grams to birds weighing as much as the owl itself, like the Spotted Nothura (Nothura maculosa). Small prey is usually torn into chunks and eaten completely with bones and all, while prey larger of about 100 g or more (such as baby rabbits, Cryptomys blesmols, or Otomys vlei rats) is usually dismembered and the inedible parts discarded. Contrary to what is sometimes assumed, the Barn Owl does not eat domestic animals on any sort of regular basis; it might snatch a young chicken or guinea pig once or twice in its life, if at all. Regionally, different foods outside of rodents are utilized as per availability. On bird-rich islands, a Barn Owl might contain some 15–20% birds in its diet, while in grassland it will gorge itself on swarming termites, or on Orthoptera such as Copiphorinae katydids, Jerusalem crickets...