The subspecies fujiyamae of Northern Goshawk Accipiter gentilis breeds in Japan, Sakhalin, and Southern Kurile Islands as an endemic subspecies (OSJ 2000). This paper shows the measurements from 64 individuals of A. g. fujiyamae caught in central Saitama and southeastern Tochigi Prefectures, Honshu, along with the identification criteria of sex and age based upon measurements (Table 1), plumage features (Fig.1), and iris colour (Table 2). Adult males were significantly smaller than adult females for all measurements (Table 1). Tails of juveniles were significantly longer than adult tails for males (t-test, tΐ2.238, dfΐ26, P0.05) and probably also for females (Table 1). We could distinguish the age as juvenile, first winter, and adult plumages based on the plumages combined with iris colour (Fig.1). A few juvenile feathers of upper and under wing-coverts remained in first winter plumage until about two years old, which was the bird's third year. Measurements from live birds tended to be larger than the data reported in the literature, which were mostly taken from specimens. The di#erence was as large as 10 mm in the case of tarsus length. The iris was pale yellow (sulfur yellow) in juvenile plumage and tended to acquire an orange tinge as the bird aged, mainly spectrum yellow or orange yellow in first winter plumage, and orange yellow or orange in adult plumage after in the second winter plumage. We show for the first time that the iris may turn red for old males of Japanese Northern Goshawks A. g. fujiyamae (Table 2 and Fig. 1).
. Nest site characteristics of four raptor species breeding in a hilly area of Tochigi and Nagano, central Japan. Jpn. J. Ornithol. 55: 48-55.Abstract. The nest site characteristics of Northern Goshawk Accipiter gentilis, Greyfaced Buzzard Butastur indicus, Buzzard Buteo buteo and Honey Buzzard Pernis apivorus were studied in Tochigi and Nagano prefectures, central Japan. Regional differences were found in the nesting tree species used by goshawk; with Japanese Cedar Cryptomeria japonica used mainly in Tochigi and Japanese Red Pine Pinus densiflora used mainly in Nagano. Other raptors also nested in Japanese Red Pine. Goshawk nested on one of the largest trees in the forest, but there was no similar tendency in Grey-faced Buzzard. The specific characteristic of the forests where goshawk nested was that they had less tree coverage in lower tree layers than forests used by other raptor species.
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