The perching behaviour of a pair of Golden Eagles Aquila chrysaetos was studied in Tazawako Town, Akita Prefecture from February 1991 to July 1993. No other pair of Golden Eagles was observed near the Tazawako pair. A total of 566 hours was spent observing the various behaviours of these Golden Eagles. Social relationships with individual Golden Eagles and with other species were analyzed to clarify the meaning of perching behaviour. Seasonal change in location and in the characteristics of the perches used by the eagles in this study were recorded. These changes in location and perch characteristics may have been influenced by breeding ecology and the breeding success or lack of success of the pair. During the nestling period, defense and offense behaviours against intruders increased around the nesting area, perhaps owing to the increase of other species or to an overlapping of the breeding stages with other species in the nestling area. Perching behaviour also increased during the nestling period. Most of the perches, both conspicuous and exposed, were observed from locations within 2 km of the nest. The elevations of these perches were either the same or were higher than the nest, providing a good view of the nest. The elevations of these perches may have been related more to advertisement behaviour for floaters, and than to neighbouring birds. In the study area, Golden Eagles lacked any obvious territorial defense against their own species, perhaps because Golden Eagles are sparsely distributed around Tazawako Town.

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Variations in fledging body weight and wing length of the Russet Sparrow Passer rutilans were studied in two different types of habitats, shelter belt and isolated forests, in south-eastern Hokkaido, Japan, during the breeding seasons of 1995 and 1996. Although neither body weight nor wing length at hatching were significantly different between the shelter belt and the isolated forests, body weight at fledging was heavier in the isolated forests than in the shelter belt. This differences in fledging body weight might be explained by the presence of a greater food supply in the isolated forests than in the shelter belt.

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