Effects of exotic mongoose (Herpestes javanicus) on the native fauna of Amami-Oshima Island, southern Japan, estimated by distribution patterns along the historical gradient of mongoose invasion |
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Authors: | Yuya Watari Seiki Takatsuki Tadashi Miyashita |
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Institution: | (1) Laboratory of Biodiversity Science, School of Agriculture and Life Science, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan;(2) The University Museum, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan |
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Abstract: | We examined the distribution patterns of native animals on Amami-Oshima Island, southern Japan, along a historical gradient
of mongoose establishment and estimated the effects of mongoose on the native fauna. To assess the relative abundance of various
ground-dwelling animals, we used the following four methods; sensor cameras for exotic mammals, nighttime driving census for
nocturnal native vertebrates, line census for ground-dwelling lizards, and adhesive traps for arthropods. The results indicated
that seven species with larger body size, including mammals, birds, reptiles, and amphibians, were rarely observed in mongoose-infested
area. By contrast, medium-sized animals showed neutral relationships with mongoose establishment. Interestingly, the densities
of smaller-sized animals were higher in mongoose-infested area. It could be interpreted that smaller species have increased
in abundance through top-down cascades, i.e., decreases in native predators such as frogs and lizards caused by the mongoose
have resulted in increases in the abundance of smaller animals. Predation pressures by mongoose and native predators may be
canceled out for medium-sized animals, causing neutral responses to mongoose by these animals. This study appears to be the
first example that shows the influence of mongoose on a wide variety of native animals. In addition, our findings indicate
the importance of considering the food web structure of a recipient ecosystem and contribute to the prediction and assessment
of ecological risks caused not only by mongoose, but also by other invasive top predators. |
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Keywords: | Amami rabbit Biological invasion Food webs Herpestes auropunctatus Island Predation Invasive predatory mammals Nansei Islands Small Indian mongoose Trophic cascade |
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