Abstract
In the Kitakami Plateau of Iwate Prefecture, there is a population of about 30 pairs of Golden Eagle Aquila chrysaetos, however breeding success has been declining rapidly, with reduction in suitable feeding grounds implicated as a primary cause. Breeding success must be 0.282 or more to maintain the population. The area of feeding grounds required within home ranges (within a radius of 6.4 km) to achieve that breeding rate was calculated using a multiple regression equation. The area was calculated to be 560 ha for young (less than 10 years old) plantations alone, 1,020 ha for pastures/meadows and abandoned areas up to 5 years after cutting alone, and 770 ha for broad-leaved deciduous forests 101 or more years of age alone. Afforestation, at a 76-year interval, will be sufficient to supply the necessary young artificial forests for the eagles' home ranges. Line thinning was also considered effective in ensuring a sufficient supply of food resources and feeding grounds for A. chrysaetos. Furthermore, it is suggested that increases in biological diversity will result from cutting and thinning operations in plantations.
