There are differing views in the literature regarding the feeding strategy of the barn owl (Tyto alba, Strigiformes). Whereas some authors conclude that the barn owl is a selective predator, selecting to prey on certain species, oth- ers maintain that it is an opportunist. We studied the diet composition of barn owls from agricultural fields in northern Israel, using pellet analysis. Over 4,000 prey items were identified, comprising a total of at least 27 species. We found that during 1997–2001 there was a significant change in the barn owl’s diet: it switched its main prey species from the Levant vole (Microtus guent theri) to two other Myomorpha species, the house mouse (Mus musculus) and Tristram’s jird (Meriones tristrami), probably as a result of changes in the field abundance of the main prey items. Hence, although our barn owls select one prey species at a certain period of time, they exhibit an opportunistic feature in their ability to easily switch between prey items in their diet.