The ecological adaptations made by the Ogasawara Greenfinch Carduelis sinica kittlitzi on the Ogasawara Islands, and its present situation, were studied during the periods 24-31 December 1995 and 4-10 April 1996. Their main breeding area was the small islands around Hahajima, and their distribution was closely related to the distribution of arid shrubs. They were mainly observed in an environment of arid shrubs. Feeding behaviours in breeding season were most frequently observed on the ground, amongst arid shrubs. Nests were found in trees, in arid shrubs, and in adjacent groves. Mean clutch size was 3.5, a size smaller than that of other popultations of the Japanese Greenfinch C. sinica minor. Mean egg size, however, was larger than that of other populations. Food items in breeding season were mainly the seeds of arid shrubs, as opposed to the seeds of grasses with other populations of Japanese Greenfinches. In spite of its small body size, the Ogasawara Greenfinches has a large bill and a longer tarsus length, given the geographic latitude at which they live. From these facts, it was concluded that Ogasawara Greenfinches have adapted to the arid shrub on the Ogasawara Islands: their large bill and long tarsus length constitute adaptations to the need to forage for seeds among the arid shrubs; their small body size and small clutch size are adaptations to subtropical climate; and their movement after breeding season to the main island of Hahajima is a moult migration closely related to the shortage of food and water during the summer season.

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The vegetation types of home ranges and the activity of Stonechats Saxicola torquata were investigated in a native shrub-grass land during their breeding season in eastern Hokkaido, Japan. They made 69% of nests in the vegetation type 1 (patches of tall plants mixed with low grasses). More than 70 % of their home range was covered by type 1 and type 2 (tall plants are scattered uniformly in low grasses). Two pairs and one male out of three pairs studied used type 1 more than expected during all breeding periods and one pair and one male also used type 2 in the incubation period and the fledgling period. Two males used type 3 (grove of Salix) and one male type 5 (tall plants grow densely) during the incubation and the fledgling periods respectively, while the uses of type 4 (low grasses) was low in all individuals. Type 1 and type 2 preferred by Stonechats as habitats may provide perches to hunt insects on the ground of open area. The feature of habitats in this study areas was similar to those in other regions.

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Characteristics of breeding sites, nest trees and holes of two woodpecker species, Dendrocopos major and D. minor, were investigated in woods and parks in the urban and rural areas of Obihiro, eastern Hokkaido from April to September 1993. In D. major the numbers of nest and birds counted per 30 minutes census increased with area size, but those of D. minor did not vary. Fledging date ranged from June 23 to July 25 with an average of July 2 for D. major and from July 3 to 20 with an average of July 11 for D. minor. Neither D. major nor D. minor showed any preference in vegetation types of nesting site. Of 42 D. major nests including those found out of study areas, 22 were in woods and 20 out of woods. On the other hand, of 9 D. minor nests, 8 were found in woods and only one nest out of woods. Nest tree height, nest height, DBH (diameter at breast height) and DNH (diameter at nest height) were 13.6m, 3.7m, 35.7cm and 28.2cm respectively for D. major, and 8.0m, 3.0m, 11.0cm and 26.6cm respectively for D. minor. D. major used both live and dead trees for nesting, while D. minor used only dead trees with several holes. The minimum DNH was 19cm for D. major and 17cm for D. minor respectively. Values indicating nest sizes and volumes of D. major were larger than those of D. minor. Conditions required for nesting of two Dendrocopos species are 1)minimum area of 1.5ha where they nested, 2)live and dead trees of more than 21 cm in DBH for D. major and 3) dead trees of more than 18cm in DBH for D. minor.

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[in Japanese]

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