Characteristics of White-Tailed Sea Eagle Nest Sites in Hokkaido, Japan

I studied the characteristics of 26 White-tailed Sea Eagle (Haliaeetus albicilla) nest trees and 24 nesting forests in Hokkaido, Japan. Nest trees were an average of 7.9 m taller and an average of 45.6 cm larger in dbh than the surrounding forest, and many of them were near the forest edge. Eagles preferred Glehn's Spruce (Picea glehnii) and Japanese Alder (Alnus japonica) as nest tree species, though not exclusively. Nests were an average of 2.8 m higher than the average height of surrounding trees, and all nests had canopy openings above them. Openings above nests in the forest interior were an average of about 110° wider than those above nests near forest edges, because the nests were built on emergent trees. Eagle nesting habitat in Hokkaido requires trees large enough to support the nest, and a surrounding structure which allows accessibility and good visibility.