CLINAL VARIATION OF FOOD-HABITS AND BREEDING SUCCESS OF THE GOLDEN EAGLE (AQUILA-CHRYSAETOS) ON THE SOUTHERN SIDE OF THE PYRENEES

Ninety two controlled reproductions and 630 remains of prey items from 23 Goden eagle pairs were studied on the southern slope of the Pyrenees (Spain). A gradual variation of breeding success and food habits was found: the proportion of carnivores, hares, carrion and corvids decreased, whereas the proportion of rabbits increased in the diet from the summit of the Pyrenees to the Ebro Valley. These variations were associated with a decrease of trophic diversity and increased breeding rates, due to a larger number of young per successful pair.