分布拡大初期にあるシカ個体群の低コストモニタリング手法の開発 ―東北野生動物管理研究交流会― Development of cost-saving techniques to detect the newly expanding sika deer populations ―Working Group for Tohoku Wildlife Management―

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<p>豪雪地を含む東北地方に分布を拡大させるニホンジカ(<i>Cervus nippon</i>;以下,シカ)の予防的対応が急がれている.そこで,従来技術では検知が困難な侵入初期段階の低密度シカ個体群でも,個体検知可能な新手法としてボイストラップ法を考案し,その技術の高度化を目的とした評価試験を東日本各地で実施した.ボイストラップ法は,オスジカの鳴き返し行動を利用したAAM法(active acoustic monitoring)と,野外に設置したレコーダーを用いてオスジカの鳴声(howlとmoanの2種の咆哮)を録音し機械学習により検知するPAM法(passive acoustic monitoring)の2つからなる.AAM法は6調査地で7セット実施し,那須地域および朝日・飯豊山系にて鳴き返しを得ることに成功した.これは,当該地域にオスの定着個体がすでに分布していることを示唆する.PAM法は5調査地で7セット実施した結果,那須地域と朝日山系にてhowlの鳴声を検知した.これらの調査地は,既往のモニタリング手法では検知が困難なシカ低密度地域であることを考えると,ボイストラップ法の検知力の高さが本研究を通して明らかにされた.</p>

<p>It is now required that precautionary measures against expanding populations of sika deer (<i>Cervus nippon</i>) in the Tohoku district including heavy snow areas. Then we have devised the new monitoring method, named "voice traps," to detect deer in areas with their low-density population, where the existing monitoring methods (e.g., spotlight counts, camera traps) are rarely effective. Here we conducted the verification tests of the voice traps in eastern Japan. The voice traps for deer are composed of two different monitoring methods; active acoustic monitoring (AAM) and passive acoustic monitoring (PAM). While the AAM is a type of sound playback survey through using the behavioral trait of male deer in rut seasons, the PAM relies on the detection of loud calls (i.e., howl and moan) spontaneously emitted by male deer with autonomous recording units and machine learning algorithm. We conducted seven evaluation tests for the AAM in six study areas and confirmed clear howl-back in the two areas (Nasu area and Asahi-Iide mountains). We then tested the PAM in five study areas and automatically detected howl sounds in two areas (Nasu area and Asahi mountains). Considering that the habitat occupation of deer was hardly confirmed by the existing monitoring methods in these study areas, the current verification tests demonstrated the higher detectability of the voice traps.</p>

Journal

  • Annual Report of Pro Natura Foundation Japan

    Annual Report of Pro Natura Foundation Japan 29(0), 52-60, 2020

    Pro Natura Foundation Japan

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