Diet and breeding success of American kestrel in central Argentina

PAULA MAITEN OROZCO VALOR; GRANDE JUAN MANUEL

boise, idaho

Conferencia; Raptor Research Foundation and neotropical raptor network 2021 Annual Conference; 2021

Agricultural expansion and intensification can completely alter food provision for birds and have negative consequences on their diet and breeding performance. The American kestrel is one of the commonest birds of prey across its breeding range in the American continent although recent evidences indicate that they are declining in areas of North America and the effects of agricultural intensification are one of the studied candidate factors. In Argentina, where an intense process of agricultural intensification took place in the last decades, the species occurs throughout the country, being traditionally linked to agroecosystems. We analyzed the diet of American kestrel nestling and the species breeding performance across a gradient of agricultural intensification from native forest, traditional farmland to intensive farmland. We found no differences in diet diversity among areas although it did change in composition. Although it was dominated by arthropods in the three areas, Orthoptera and vertebrates were more frequent in the forest while they were complemented with other groups of arthropods in both agricultural areas, suggesting that changes in land use generate a functional response in the American kestrel?s diet.The extension of pastures surrounding nest boxes had positive effects on the probability of breeding successfully while climatic variables had strong effects on the species breeding timing, productivity and probability of breeding successfully. Our results highlight the relevance of pastures and grasslands for American kestrel reproduction. These environments are the most affected by land-use change to intensive agriculture in Argentina indicating a potential large-scale effect on the species breeding output. Long-term analysis of diet variation in relation with land-uses and its effects on breeding performance may shed light on the way through which agricultural intensification shapes American kestrels? reproduction.