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The diets of Little Owls (Athene noctua) and Long-eared Owls (Asio otus) have been studied extensively, although seldom in desert habitats where they coexist. We compared diets of these two species near the Minqin Desert Experimental Research Station in northwestern China. Diets differed significantly by frequency: Little Owls fed mainly on mammals (56%) and beetles (42%), and Long-eared Owls fed almost exclusively on mammals (97%). Dietary overlap was 0.62. Diets differed significantly in four dimensions: prey size, feeding time, feeding habitat, and prey mass, and the overlaps for these dimensions were less than 0.74. However, at the generic level for mammals, the difference was not significant, and dietary overlap was 0.97, indicating that they fed on similar mammal assemblages. The overlap for presumed feeding time and habitat was almost complete for mammals. However, owls consumed mammals of different size; overlap of mammal size was 0.74. Our results indicate that although the roost sites of the two owl species were in close proximity and the main prey species overlapped extensively, the owls coexisted mainly by consuming prey of different size.