カワネズミの捕獲, 生息環境および活動  [in Japanese] Trapping, Habitat, and Activity of the Japanese Water Shrew, Chimarrogate platycephala  [in Japanese]

Access this Article

Search this Article

Abstract

本州,九州,四国および隠岐島(島後)のほぼ全域にわたる63水系,191箇所において大型はじきワナ(幅 8.5cm,長さ 14cm)によるカワネズミ Chimarrogale platycephala の捕獲を行い,本州と九州の調査地177箇所中86箇所から139個体を捕獲した.四国と隠岐島(島後)では良好な環境でも全く捕獲できなかったことから,従来の予測通り生息しないものと考えられた.河床沿いの線状ワナかけによるワナ数と捕獲結果の関係から,カワネズミは個体ごとの縄張りをもつことが示唆された.生息地の標高分布の下限は北方で低く,南方で高い傾向があり,その上限は川の源流の標高に依存した.昼間の活動個体目撃例や捕獲例が比較的多いことから,カワネズミは1日複数回の活動周期を持つことが示唆された.相対的に遮蔽物の少ない河床環境において昼間も活動するカワネズミにとっては,下側に空隙や陰を作る岩や倒木などが数m から 10m 程度の間隔で存在するような河床環境が生息場所としての重要な条件であることが分かった.また,川岸が水流によって削られた河岸洗掘洞も同様の働きを持つ環境要素であった.これらの環境要素を備えたところでもカワネズミの採集されない川が多く見られたが,その場合には,濁流の発生をもたらし,水生昆虫相を壊滅させる各種土木工事等が上流側で行われているか,あるいは過去に行われたと思われる例が多く見られた.そのことから,カワネズミは環境の人為的改変に対して大変脆弱な動物であることが示唆された.

Trapping by snap-traps (8.5cm wide, 14cm long) with raw fish meats was carried out at 191 sites along 63 river systems ranging from Honshu, Kyushu, Shikoku, to Oki, Japan. One hundred and thirty-nine specimens of the Japanese water shrew, Chimarrogale platycephala, were obtained from 86 sites in 177 sites in Honshu and Kyushu. No specimens were found in Shikoku and Oki Islands. The relationships between the number of traps set at each trapline and the number of water shrewes caught revealed that the water shrew was a territorial creature. The lower limits in the altitudinal distribution of habitat were lower in northern districts compared with southern habitats. The upper limits appeared to be depending on the altitude of the uppermost stream of each river. Field observations suggested that the water shrew had plural activity cycles in a day. Preferable habitats for the water shrew were swift streams or rivers with abundant shelters on the river bed; the shelters usually consist of boulders, large rocks or fallen logs with underside cavities or slits and/or of water-eroded cavities made along river bank. There were many instances in which no water shrews were trapped, although the habitats retained a full composition of the above elements. In many of these cases, engineering works such as construction of roads, dams, pastures, ski grounds, etc. were observed on the upper streams or on the catchment of the river. These construction works produced muddy water flow which affected the aquatic insects that the water shrew fed on. These observations suggested that the water shrew was very sensitive to the artificial change in the river environments.

Journal

  • Honyurui Kagaku (Mammalian Science)

    Honyurui Kagaku (Mammalian Science) 43(1), 51-65, 2003-06-30

    The Mammal Society of Japan

References:  23

Cited by:  5

Codes

  • NII Article ID (NAID)
    10011246940
  • NII NACSIS-CAT ID (NCID)
    AN00231656
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0385437X
  • NDL Article ID
    6629570
  • NDL Source Classification
    ZR4(科学技術--生物学--動物)
  • NDL Call No.
    Z18-1160
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
Page Top