4 June, 2022
Banding American Kestrels allows researchers to monitor them over time. Photo courtesy of Paula Orozco.
The conversion of natural ecosystems into farmlands alters the abundance and availability of food for wildlife. Traditional agroecosystems, which include the rotation of crops, cattle raising, and the presence of patches of natural forest and pastures, maintain a high abundance of birds, rodents, and insects that serve as prey for larger animals. However, agricultural expansion and intensification at the expense of natural environments has been linked to declines in biodiversity.
As predators that depend on healthy prey populations, raptors may serve as indicators of the effects of modern agricultural practices on wildlife communities. With support from IBCP, Dr. Paula M. Orozco Valor is studying the American Kestrel (Falco sparverius), the smallest falcon in the Americas and a species linked to traditional agroecosystems in Argentina. Although they are among the most common raptors in the Americas, American Kestrel populations are declining across several regions for reasons that remain unclear.
Paula Orozco measures a rodent as part of a survey of wildlife hunted by American Kestrels. Photo courtesy of Paula Orozco.
Do agroecosystems provide different prey for kestrels than natural environments, and if so, do they impose a cost on birds’ fitness, survival, and/or reproductive success? Paula is investigating these questions in her postdoctoral research at CONICET, which will identify the potential costs of agricultural intensification for America Kestrels. Working in agroecosystems and natural forests in La Pampa, Argentina, Paula has been monitoring over 100 kestrel nest boxes and banding nesting kestrels and their chicks in an effort to find out how agricultural intensification affects them. Kestrels prefer open areas for hunting, so she expected that nest box occupancy would be higher in agroecosystems, but that the availability of wildlife hunted by in these agroecosystems might be limited.
Researchers check a kestrel nest box in La Pampa, Argentina. Photo courtesy of Paula Orozco.
Paula will test whether changes in kestrels’ diets may be linked to demographic changes, such as differences in the number of young or variation in birds’ survival. To this end, Paula and her collaborators have made counts of invertebrates, small mammals, and birds during the kestrel nesting season. Paula has also collected kestrel prey remains and pellets to analyze the relationship between kestrel prey consumption and prey availability in the field. Paula’s preliminary results highlight how the maintenance of remnants of natural vegetation in agroecosystems, such as by roadsides and railways where kestrels focus their hunting efforts, benefit raptors. We look forward to learning from her results, which will contribute to our understanding of how farming practices impact birds and ecosystems, and how we can improve the sustainability of agriculture and the conservation of biodiversity.
Paula Orozco checks a nesting American Kestrel as part of her study. Photo courtesy of Paula Orozco.