Ecologie d’une population de rapaces diurnes en lorraine

The seasonal changes in population density of diurnal birds of prey living in a 148 square kilometres area in north-east France have been studied from October 1965 to July 1966. This part of the Lorraine is still rather densely forested and sparsely populated. Thus predators are rather abundant. The eight dominant species are the Ruzzard, the Goshawk, the Sparrow hawk, the Red kite, the Rlack kite, the Honey buzzard, the Marsh harrier and the Hobby. Data on population density at various times of the year, on fecundity, and nesting success are given on tables 1 and 2. Habitat preferences, hunting methods, size of home range (table 5) are discussed. Food habits and their seasonal variations have been studied (tables 6 and 7) and an estimation was made of the daily food consumption of the more abundant species. On the whole there was no major « ecological overlap » of the niches of the diurnal birds of prey (table 8) in that part of France. A ten tative estimation of the metabolic impact of bird and mammal predators upon the Vertebrate community was made (tables 9, 10, 11, 12). Diurnal birds of prey exert a « predation pressure » which is 10 to 20 times smaller than that of owls and mammalian carnivores taken together. However their selective role must not be underestimated