The importance of competition, food, habitat, weather and phenotype for the reproduction of Buzzard Buteo buteo

Abstract

Capsule: Variation in reproduction between territories was strongly influenced by intra- and interspecific competition, phenotype, levels of rainfall and human disturbance. Aims: To assess the relative importance of competition, food, habitat quality, weather and phenotype as predictors of variation in reproduction in Buzzard. Methods: Annual breeding data were collected from 1989 to 1996 in a 300-km2 study area and related to 35 independent variables through multivariate regression models. Results: Significant predictors of variation in reproduction between territories (78% variance explained) were variables describing intra- and interspecific competition, plumage morph, laying date, precipitation levels and anthropogenic disturbances in the breeding territory. Competition and plumage morph seem to be particularly important, as these variables explained a high level of variation (81%) in the 1996 reproduction of this population. Conclusion: The potential importance of competition, plumage morph and precipitation for reproduction in this Buzzard population is emphasized.