Diet and provision rates of American kestrel in natural environments and Pampean agroecosystems

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

Fort Collins

Congreso; Raptor Research Foundation Annual Conference 2019; 2019

Raptor Research Foundation

Argentinean agroecosystems have suffered a marked process of agriculture expansion and intensification in the last decades. The substitution of natural habitats by crops can completely alter food abundance and availability for raptors. We searched for changes in diet composition and in parental investment of American Kestrels (Falco sparverius) in areas of intensive agriculture, traditional agriculture and natural semi-arid forests of central Argentina. We analyzed video recordings at 30 nest boxes during the nestling period in the 2017 breeding season (n = 97.5 hours). Diet diversity was greater in agricultural areas than in the Caldén forests, suggesting a functional response in the species diet. Although no statistical differences were found in the frequency of consumption of the main prey items among study areas, the relationships observed match those of previous diet analysis in the area. The biomass contribution to nests did not vary between areas. However, the provision rate was higher in agricultural areas and lower in the Caldén forest. Males and females showed a differential provision rate that changed with nestling age, where females contributed more towards the end of the breeding season. These results suggest a role division between sexes. In addition, the reproduction in agricultural areas demanded a greater parental investment, possibly due to lower availability of the most suitable prey and a diversification of the diet including less profitable items. Further studies are needed to quantify the possible costs to adults of this higher parental investment in agricultural lands and to analyze if these costs are also transferred to nestlings.