Diet of the Montagu's Harrier Circus pygargus nesting in natural habitat in Eastern Spain

Abstract

We describe the diet of the Montagu’s Harrier (Circus pygargus) population breeding in inland Castellón province (eastern Spain), which exhibits among the highest breeding productivity of European populations of this species. We assessed diet using pellets collected at nests at the end of the breeding season. We recorded the minimum number of items in every pellet for six prey classes (lizards, passerines, small mammals, coleopterans, orthopterans and other insects).We also analyzed between-year relationships in diet diversity and breeding output at the nest level. The most frequently eaten prey were insects, particularly large orthopterans of the family Acrididae. Passerines were also abundant in the diet and contributedmore than 50% of the consumed biomass. We found no significant between-year relationship in breeding output and diet diversity at the nest level. Further studies on prey availability in different habitat types would be needed in order to understand how land-use changes affect the Montagu’s Harrier population.