本研究は野生カルガモを、ニワトリの育成用飼料を用いて育成し、その体重の成長パターンを明らかにするために、3点法によるRichardsの成長曲線モデルの当てはめを行った。あてはめ計算のための測定週齢の組合せ数は12組を設定し、m値は0から2.0まで0.1間隔に設定して、それぞれの曲線モデル式を推定した。適合度は決定係数(R^2)の大・小によって判定した。(1)カルガモの成長パターンは初期成長が旺盛で、変曲点時週齢は雄では4.36週齢、雌は3.76週齢であり、アヒル(中国産ペキン種)の変曲時週齢に近い。(2)12組の測定週齢の組合せの中で、最も高いR^2値をえたm値では1-8-19週齢の1.1(R^2=99.74%)、雌は1-9-20週齢の0.8(R^2=99.40%)である。したがって、成長型は雄はGompertz曲線に近く、雌はBertalanffyよりGompertz曲線への移行型と考えられる。(3)決定係数(R^2)と規値の関係は、アヒルやニワトリと同様に1本の曲線で表現される。

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1976〜1996年の4月下旬〜7月中旬に北海道中部と南東部において繁殖期のカケスの分布を調べた。カケスは森林と農耕地で観察されたが、住宅地とハイマツ林帯では見られなかった。出現率は常緑針葉樹林で50%、針広混交林で35%、落葉広葉樹林で34%で、カラマツ人工林で28%、農耕地・林で19%、農耕地で7%であった。標高別では、主に600m以下で出現率が比較的高く、垂直分布の上限は標高900m台であった。カケスは、カラス科鳥類のなかでは森林に強く依存する種といえる。

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The breeding sites and the number of egg masses of Hynobius retardatus and Rana pirica were surveyed in 755ha of the northeast area of Nopporo Natural Forest Park, Hokkaido Japan. There were 53 breeding sites of Hynobius retardatus, and the total number of egg masses was 788. While the sites of Rana pirica were 24, there were 398 in total. Among these respective breeding sites, 17 sites were used by both species. Hynobius retardatus began laying eggs when the water temperatuer was between 7 and 8℃, and increased noticeably when the water temperature reached 10℃. On the other hand, Rana pirica began laying eggs at 10℃C, and egg laying increased noticeably when the water temperature reached 12℃. My research indicates that both species instinctively return to the same breeding sites every breeding season. In order to further research the breeding dynamics of these two species, it is useful to record number of egg masses and breeding sites of both species.

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Twenty-six (2 male and 24 female) adult Ixodes persulcatus were collected from one Mustela sibirica which had died in Nopporo Forest Park, Hokkaido, Japan. To my knowledge, this in the first record of Ixodes persulcatus being collected from M. sibirica in Japan.

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As a zoogeographical research, an analysis was made on the parasitic nematode fauna of the Japanese Microtinae and Murinae (Mammalia: Rodentia: Muridae), viz., Clethrionomys rufocanus bedfordiae, C. rutilus mikado, C. rex, Eothenomys andersoni, E. smithii, Microtus montebelli, Apodemus speciosus, A. argenteus and A. peninsulae. A total of 3113 individuals were examined, and 32 nematode species were obtained. Among these nematodes, the speciation and geographical distribution of the Heligmosomoides (Heligmosomidae: Strongylida) were discussed in regard to the fossil records of host mammals and the geological record of the Japanese archipelago. It is considered that H. desportesi was derived from the central part of the Eurasian Continent in the Early Pleistocene and H. kurilensis was derived from Siberia in the Middle Pleistocene. H. neopolygyrus which occurrs in the eastern part of the Eurasian Continent migrated via northern land bridges in the Wurm Glacial Ages. Hence, the formation of parasitic nematode fauna of an endemic rodent group was related to the environment and to the mammalian fauna of the pre-Japanese archipelago in the Pleistocene.

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