Kubo Kotaro, Tachikawa Taisei, Hirose Miki, Hasegawa Masami, Inoue Eiji
Department of biology, Faculty of science, Toho University, Funabashi, Chiba, Japan.
PLoS One. 2025 May 30;20(5):e0324200. doi: 10.1371/journal.pone.0324200. eCollection 2025.
Understanding habitat use and abundance is essential for elucidating the impact of invasive species. Invasive carnivores affect ecosystems by preying on native animals. In Japan, the Japanese weasel (Mustela itatsi) is native to the mainland but has been intentionally introduced to many small islands, including Miyakejima Island. We investigated the habitat use and abundance of invasive non-native Japanese weasels on Miyakejima Island via fecal surveys, and for comparison, performed similar surveys for their native conspecifics on Izu-Oshima Island. We constructed a generalized linear mixed model and estimated fecal abundance across the entire island based on the effect of vegetation type on their abundance. On Miyakejima Island, deciduous broadleaf and bamboo forests had positive effects on weasel abundance, whereas grasslands had a negative effect. Conversely, on Izu-Oshima Island, bare ground had a negative effect. Further, the estimated average fecal abundance across Miyakejima and Izu-Ohshima Islands, considering vegetation type, were 7.44 and 4.89 feces samples per km, respectively, suggesting that weasels are well adapted to Miyakejima Island. We also analyzed the fecal DNA of weasels in a specific area on Miyakejima Island and estimated non-native weasel density at 20 individuals per km2 (95% CI: 4.9-80) using genetic capture-recapture methods in the area. These findings enhance understanding regarding non-native species and may facilitate the formulation of countermeasures for their control.
了解栖息地利用情况和数量对于阐明入侵物种的影响至关重要。入侵食肉动物通过捕食本地动物来影响生态系统。在日本，日本鼬（Mustela itatsi）原产于大陆，但已被有意引入到包括御藏岛在内的许多小岛屿。我们通过粪便调查研究了御藏岛上入侵的非本地日本鼬的栖息地利用情况和数量，并作为比较，对伊豆大岛上它们的本地同种动物进行了类似调查。我们构建了一个广义线性混合模型，并根据植被类型对其数量的影响来估计全岛的粪便数量。在御藏岛上，落叶阔叶林和竹林对鼬的数量有积极影响，而草地则有负面影响。相反，在伊豆大岛上，裸地有负面影响。此外，考虑到植被类型，御藏岛和伊豆大岛估计的平均粪便数量分别为每公里7.44个和4.89个粪便样本，这表明鼬很适应御藏岛。我们还分析了御藏岛特定区域内鼬的粪便DNA，并使用该区域的遗传捕获 - 重捕方法估计非本地鼬的密度为每平方公里20只个体（95%置信区间：4.9 - 80）。这些发现增进了对非本地物种的了解，并可能有助于制定控制它们的对策。
