SARASOLA, J.H., M.A. SANTILLAN & M.A. GALMES. 2003. Food habits and foraging ecology of American Kestrels in the semiarid forests of Central Argentina. Journal of Raptor Research 37(3):236-243.
Abstract: The annual diet of the American Kestrel (Falco sparverius) was studied by analyzing 705 pellets and prey remains collected in a semiarid forest area of central Argentina. The diet composition fluctuated seasonally but was composed primarily of invertebrates, followed by small mammals, birds, and reptiles. Based on biomass, vertebrate prey was the major component of the diet in winter and spring. We found signiﬁcant numerical differences between prey consumed by adult and nestling kestrels. Percentages of small mammal prey were higher in the diet of adults than in the nestlings, but rodents consumed by nestlings were larger in size than consumed by adults. Nestlings also ate more birds and reptiles than adults. Based on biomass contribution of vertebrate and invertebrate prey to the diet during non-breeding and breeding seasons, American Kestrels in semiarid forest of Central Argentina were more carnivorous than insectivorous predators. Differences between adult and nestling diets emphasized the importance of collecting samples from perches and nests when kestrel food habits are being studied during the breeding season.
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