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.

Land abandonment and changes in snow cover period accelerate range expansions of sika deer

“…Our results revealed the importance of the snow cover period compared with the maximum snow depth, which had been used in previous studies (Kaji et al., ; Okumura et al., ; Saito et al., ). In snowy regions in Japan, evergreen dwarf bamboo species dominate on the forest floor (Tsuyama et al., , ), and snow cover prevents the access to this forage.…”

“…We found here that habitat suitability of sika deer was explained by a combination of climatic variables, land-use variables, and topographic variables (Table 1). Our results revealed the importance of the snow cover period compared with the maximum snow depth, which had been used in previous studies (Kaji et al, 2000;Okumura et al, 2009;Saito et al, 2016). In snowy regions in Japan, evergreen dwarf bamboo species dominate on the forest floor (Tsuyama et al, 2011(Tsuyama et al, , 2012, and snow cover prevents the access to this forage.…”

A systematic review of the impacts and management of introduced deer (family Cervidae) in Australia

“…Other approaches that have been considered internationally include limiting the use of key habitats for deer range expansion, for example, through fencing ecotone areas and manipulation of forest and agricultual landscape matrixes (Saito et al 2016). Scare devices and repellents (topical application of distasteful chemicals or predator scent) may be useful at high-value sites, but are generally effective for short periods only (weeks-months) (Walter et al 2010).…”

Regional variability in landscape effects on forest bird communities

“…Our large number of sites with just a single year's data, and therefore number of levels of the random effect with just one observation, would artificially reduce the 95% confidence intervals (Harrison 2015). Sites outside of the four main islands of the Japanese Archipelago were excluded, due to their very different biogeography, outlying values of climate variables, and to control for island-size effects on regional species pools (Yamaura et al 2011;Saito et al 2016;Fukasawa and Akasaka 2019;Kawamura et al 2019). We also excluded transects for which environmental data (climate and land cover) could not be obtained (Katayama et al 2014), giving a total of 297 forest sites available for analysis (Appendix S2).…”