Diet and Breeding Success of American Kestrels in Natural and Agricultural Lands in Central Argentina

OROZCO-VALOR, P. M.; GRANDE, J. M.

Boise, virtual

Conferencia; Raptor Research Foundation 2021 Annual Conference; 2021

Raptor Research Foundation and The Peregrine Fund

Agricultural expansion and intensifi cation can alter food provisions for birds and havenegative consequences on their diet and breeding performance. The American Kestrel (Falcosparverius) is one of the commonest birds of prey across its breeding range. Recent evidenceindicates that they are declining in areas of North America, and the effects of agriculturalintensifi cation are one of the studied candidate factors. In Argentina, where intenseagricultural intensifi cation has taken place over the last decades, the species occursthroughout the country primarily in areas of agroecosystems. We analyzed the diet ofAmerican Kestrel nestlings and species breeding performance across native forest, traditionalfarmland, and intensive farmland. We found no differences in diet diversity but did fi nddifferences in composition. Diet was dominated by arthropods in all three areas, withOrthoptera and vertebrates found more frequently in native forest. Diet was complemented byother groups of arthropods in both agricultural areas, suggesting that changes in land usegenerate a functional response in the American Kestrel?s diet. The extension of pasturessurrounding nest boxes had positive effects on the probability of breeding success, whileclimatic variables had strong effects on the species breeding timing, productivity andprobability of breeding success. Our results highlight the relevance of pastures and grasslandsfor American Kestrel reproduction. These environments are the most affected by land-usechange to intensive agriculture in Argentina indicating a potential large-scale effect on thespecies breeding output. Long-term analysis of diet variation in relation with land-uses and itseffects on breeding performance may shed light on the way through which agriculturalintensifi cation shapes American Kestrels? reproduction.