Population trend and breeding biology of Montagu's Harrier Circus pygargus in a natural vegetation site in northeast Spain

Abstract

Capsule: Reproductive output in a natural habitat was higher than in birds breeding in cereal crops, highlighting the importance of natural habitats for the species. Aims: To evaluate breeding in a natural habitat in inland Castellon province, Spain, and compare breeding parameters with other European populations. Methods: Breeding population size in inland Castellon was recorded between 1981 and 2003. A logistic growth model was used to describe population increase. We also calculated clutch size, brood size, productivity, percentage of successful nests and fledging success for the period 1989–2003. Results: Population size increased from three pairs in 1981 to 98 pairs in 2003. During 1989–2003, productivity (2.74 ± 1.49 fledglings/pair) and percentage of successful nests (84.37%) were higher than observed in other European populations. Conclusions: Our results show the importance of our study area for the conservation of this species in the Iberian Peninsula, as it might act as a source of colonists for other areas. Food and protection against predators might explain the high breeding output, which may in turn explain the rapid population growth in the area. The study also suggests that natural habitats might be important for the species elsewhere.