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A wide literature exists on the food habits of the Burrowing Owl (Athene cunicularia) in South America. However, this information is scarce for the arid lands of Argentina. Owl’s diet composition in the Somuncura Plateau and its seasonal variations were estimated. The Somuncura landscape is a volcanic plateau conformed by superimposed layers of basalt flows. The climate is arid and cold and the vegetation is characterized by a grassy steppe of the Patagonian Phytogeographical Province. Pellets were collected during late spring and late summer around two lagoons from upper elevations (41 degrees 25’35’’s, 66 degrees 57’27’’W, 1412 m a.s.l.). These were measured, dissected and prey were identified and quantified. Sample richness, biomass and food-niche breadth were calculated as dietary parameters. Small mammals availability was estimated by trapping. The Burrowing Owl showed a generalist diet, including a wide variety of prey from invertebrates to vertebrates. Coleopterans were dominant in the spring diet, while rodents and arachnids became important in the late summer diet. The high species richness detected in this study through the analysis of raptor pellets is valuable for biodiversity assessments of unexplored areas such as Somuncura.