Not called Barn Owl for nothing, these birds are drawn like magnets to disused old barns like this one on Twenty Four Rivers Farm. If a nest box is placed against an inside wall of such a barn the birds will breed in it year after year and provide the landowner with a free rodent-catching service. An analysis of the prey remains in pellets collected in this barn yielded 440 prey items of which 85% were rodents (246 items) and shrews (126 items). Here, musk shrews and climbing mice were the most frequently taken species, but this varies according to site.