Diet of Montagu's Harrier Circus pygargus in central Spain: analysis of temporal and geographic variation

The diet of Montagu's Harrier Circus pygargus was studied for 4 years near Madrid, Spain, with the use of pellets and prey remains collected during the breeding season. The diet of the study birds included a wide variety of prey categories, the most important one by weight being lagomorphs (mainly Hares Lepus granatensis ). The diet varied seasonally, with Hares predominating early in the breeding season, while birds increased in importance later. The shift was partly a result of variation in availability (with fledgling birds being more abundant late in the season), but statistical analysis suggested that lagomorphs and then birds were actively chosen in the prelaying and nestling periods, respectively. Montagu's Harrier seemed to be an opportunistic species, hunting a wider range of prey types in more southern latitudes, but specialized in each region in the prey species that was most profitable. This was the only study on Montagu's Harriers to date which found lagomorphs to be the most important part of the diet throughout the season.