INFLUENCE OF PREY AVAILABILITY ON REESTABLISHMENT OF GOSHAWK ACCIPITER-GENTILIS NESTING TERRITORIES

Despite many years of protection, nesting Goshawks (Accipiter gentilis ) are still killed by man in Norway to save small game, especially gro use, from predation. In a 650-km(2) area in southern Norway, the re-es tablishment of Goshawk nesting territories was studied during four, 4- year periods 1972-75, 1980-83, 1984-87 and 1988-91. After a reduction in the Red Fox (Vulpes vulpes) population because of an infestation of sarcoptic mange, the grouse population increased during 1984-87, and then remained high for the rest of the study period. The number of Gos hawk nesting territories per 100 km(2) was three/year in 1972-75 and i n 1980-83, and four/year in 1988-91. During these periods, the nesting territories were regularly spaced, and their number and distribution were unaffected by the removal of breeding birds. During 1984-87, five nesting territories, in which one or both of the breeding hawks had b een removed by man, were replaced by eleven new ones. The study result s indicate that removal of breeding pairs of goshawks may lead to an i ncrease in the breeding density during periods of increasing food avai lability.