Range-expanding wildlife: modelling the distribution of large mammals in Japan, with management implications

Abstract

The spatial distribution of large mammals has been increasing in industrial nations, often leading to conflicts with humans and significant alteration of natural ecosystems. Species distribution models (SDMs) of the sika deer, Japanese serow, wild boar, Japanese macaque and Asiatic black bear in Japan were constructed to identify the important factors for habitat management. We also projected two scenarios of their future range expansions under a scenario of no change in the variables, and one where the variables change according to a time series. Modelling showed that all species preferred forest and forest/agricultural ecotones. In the best models of the sika deer and wild boar, grasslands (GRASSs) were an important positive factor, while human population density and hunting pressures were negative factors. High human population density was also a negative factor with the Japanese serow and Asiatic black bear. Key environments for the distribution and expansion of large mammals were agricultural areas near forest and GRASSs. Therefore, limiting the access of large mammals to such habitats may contribute to wildlife management. In both scenarios, our projections suggest that the distributions of all species could expand by 2028, resulting in more conflict with humans and significant alterations to natural ecosystems in the future. In order to stop this damaging expansion, habitat management and landscape redesign are important. However, a SDM and future projection include uncertainty. It is necessary to validate the estimates and projections by monitoring the future changes in distribution.