Diet and provision rates of American kestrel (Falco sparverius) in natural environments and Pampean agroecosystems

PAULA MAITEN OROZCO VALOR; GRANDE JUAN MANUEL

Fort Collins,

Conferencia; Annual Meeting of the Raptor Research Foundation; 2019

raptor research foundation

The substitution of natural habitats for crops can completely alter food availability and abundance patterns for raptors. Through the analysis of video recording carried out in nest boxes during the nestling period in 2017 breeding season, we analyzed whether there are changes in diet composition and in parental care of American kestrel in areas of intensive agriculture, traditional agriculture and natural semi-arid forests. 30 nest boxes were filmed in the three sampling areas (97.5 hours). Diet diversity was greater in agricultural areas than in the Caldén forest reserve, suggesting a functional response of the species. Although no differences were found in the occurrence frequency of the main prey items, the relationships are similar to previous works. The biomass contributions did not vary between areas. However, the contribution rate was higher in the agricultural areas and lower in the Caldén forest. Males and females showed a differential provision rate based on nestlings age, where females contributed more towards the end of the breeding season. These results suggest a roles division between sexes. In addition, the reproduction in agricultural areas demands a greater parental investment, possibly due to a lower availability of the most suitable prey and a need to diversify the diet including less profitable items. It would be desirable to analyze which be the possible costs to adults associated to this differential investment between environments and if these differences are also transferred to individual indicators of the nestlings.