Factors explaining the extension of the sika deer's range in Nikko, Japan

Context Since the introduction of fallow deer (Dama dama) to Tasmania in the early 1830s, the management of the species has been conflicted; the species is partially protected as a recreational hunting resource, yet simultaneously recognised as an invasive species because of its environmental impact and the biosecurity risk that it poses. The range and abundance of fallow deer in Tasmania has evidently increased over the past three decades. In the 1970s, it was estimated that ~7000–8000 deer were distributed in three distinct subpopulations occupying a region of ~400 000 ha (generally centred around the original introduction sites). By the early 2000s, the estimated population size had more than tripled to ~20 000–30 000 deer occupying 2.1 million ha. No study has attempted to predict what further growth in this population is likely. Aims The purpose of our study was to provide a preliminary estimate of the future population range and abundance of fallow deer in Tasmania under different management scenarios. Methods We developed a spatially explicit, deterministic population model for fallow deer in Tasmania, based on estimates of demographic parameters linked to a species distribution model. Spatial variation in abundance was incorporated into the model by setting carrying capacity as a function of climate suitability. Key results On the basis of a conservative estimate of population growth for the species, and without active management beyond the current policy of hunting and crop protection permits, abundance of fallow deer is estimated to increase substantially in the next 10 years. Uncontrolled, the population could exceed 1 million animals by the middle of the 21st century. This potential increase is a function both of local increase in abundance and extension of range. Conclusions Our results identify areas at high risk of impact from fallow deer in the near future, including ecologically sensitive areas of Tasmania (e.g. the Tasmanian Wilderness World Heritage Area). Implications The research approach and results are presented as a contribution to debate and decisions about the management of fallow deer in Tasmania. In particular, they provide a considered basis for anticipating future impacts of deer in Tasmania and prioritising management to mitigate impact in ecologically sensitive areas.

Hunting and habitat loss led to the extinction of the Formosan sika deer Cervus nippon taiouanus population in the wild in 1969. A sika deer restoration program has been in place in Kenting National Park (KTNP), Taiwan since 1984. Human—deer conflicts have increased following wild deer population growth. Understanding residents' attitudes toward reintroduced sika deer is vital to management policies. To investigate the local residents' attitudes, we collected 228 questionnaires through personal interviews in 2010. A majority of the respondents agreed that they would be happy to encounter a wild sika deer (78.1%), and a majority supported the restoration program in the KTNP (75.4%). However, 59.1% of the respondents knew little concerning the restoration program. Approximately half of the respondents (47.8%) thought that sika deer caused damages to crops, and 18.4% of the respondents actually suffered crop damages from deer. The farmers and people living within the deer's range were more vulnerable to deer damage; therefore, they were more aware of deer damage to their crops and livelihoods than non‐farmers and people living outside of the deer's range. In addition, most respondents (87.2%) considered sika deer as an attractive tourism resource and were supportive of the development of ecotourism (87.3%). We recommend that the KTNP should improve public participation, environmental education, and communication with the local people. The development of community‐based ecotourism would increase the benefits of the reintroduction of sika deer and would help to mitigate human—deer conflicts.

Ongoing climate change and land‐use change have the potential to substantially alter the distribution of large herbivores. This may result in drastic changes in ecosystems by changing plant–herbivore interactions. Here, we developed a model explaining sika deer persistence and colonization between 25 years in terms of neighborhood occupancy and habitat suitability. We used climatic, land‐use, and topographic variables to calculate the habitat suitability and evaluated the contributions of the variables to past range changes of sika deer. We used this model to predict the changes in the range of sika deer over the next 100 years under four scenario groups with the combination of land‐use change and climate change. Our results showed that both climate change and land‐use change had affected the range of sika deer in the past 25 years. Habitat suitability increased in northern or mountainous regions, which account for 71.6% of Japan, in line with a decrease in the snow cover period. Habitat suitability decreased in suburban areas, which account for 28.4% of Japan, corresponding to land‐use changes related to urbanization. In the next 100 years, the decrease in snow cover period and the increase in land abandonment were predicted to accelerate the range expansion of sika deer. Comparison of these two driving factors revealed that climate change will contribute more to range expansion, particularly from the 2070s onward. In scenarios that assumed the influence of both climate change and land‐use change, the total sika deer range increased by between +4.6% and +11.9% from the baseline scenario. Climate change and land‐use change will require additional efforts for future management of sika deer, particularly in the long term.

A shrinking human population in an area induces changes in land-use patterns; abandoned farmlands across Japan have expanded, which has increased the number and distribution of sika deer populations, resulting in serious damage to agriculture, forestry, and natural vegetation. Deer ranges have expanded close to human settlements, which has increased the risk to human health (deer-vehicle collisions and infectious diseases). Sika deer exhibit high ecological plasticity in movement patterns, density-dependent food switching, and population growth rates depending on habitat quality. Sika deer can survive using low-quality food, and their life history traits such as reproduction rate were rarely affected by their density leading to a sustained high density even in degrading habitats, suggesting that sika deer are highly evolved K-selected species. Under long-term grazing, aboveground body and the seed bank of palatable species will disappear quickly. Thus, the ecosystem resilience will be lost, and the vegetation in the area will not return to its original state even if the deer population is reduced to a lower density by culling. Therefore, the monitoring of forest vegetation and deer population management at low density should be integrated. A wide range of information and evidence-based policymaking should be integrated to successfully manage the highly plastic sika deer populations in a society with a shrinking human population. In the last chapter, we summarized the ecological plasticity of sika deer, focusing on its movement patterns, population dynamics, food habits, and various impacts on ecosystems to deepen our understanding about them. We then considered the role of humans in the ecosystems as users and engineers, which caused drastic changes in deer distribution and population size. The distribution range of deer has expanded to the northern and mountainous areas in response to a decrease in the snow cover period in the past 25 years (Ohashi et al., Ecol Evol 6:7763–7775, 2016). Their distribution range covered 70% of the country as of 2018, and it is expanding at a constant speed, especially in the historical range of the northern part of Honshu (Chap. 2). The expansion of deer distribution is expected to accelerate further with decreasing snow cover period (Chap. 3). In Japan, the human population is shrinking faster than that in the rest of the world. Moreover, the population is concentrated in cities associated with declining primary industries, which has led to a rapid decline in land use and management pressure in rural areas, including a rapid increase in abandoned farmland, a declining hunting population, and an aging population (Tsunoda and Enari, Conserv Biol 34:819–828, 2020). Here, we discuss the future management directions for developing resilient forests and sustainable social-ecological systems in a shrinking society.

This work studies the effect of the reduction of steppe and tundra landscapes in Northern Asia during the Late Pleistocene and Holocene climatic changes on the ranges of large herbivorous mammals. The relationship between a complex of characteristics of herbivore species and their landscape was evaluated. It is found that not only the Mongolian gazelle, saiga, and musk ox, but also the snow sheep, the ancestors of domestic sheep and goats, and probably the Amur goral may reduced their ranges during the late Quaternary landscape changes. The widening of the range of the sika deer, as well as the range of the Siberian musk deer associated exclusively with forest landscapes, can be explained by a reduction of open landscapes. Any significant changes in the ranges of roe deer, red deer, reindeer, elk, wild boar, steppe bison, mammoth, woolly rhinoceros, and ancestral and probably related forms of domestic horse and cattle could not be directly caused by landscape changes 17 000–7000 years ago, even if they coincide chronologically.

Simple SummaryInvestigating the interspecific interactions between species provides a suitable model for understanding the mechanisms of coexistence between sympatric species. We assessed the spatial and temporal partitioning of spaces between Japanese serows (Capricornis crispus) and sika deer (Cervus nippon), which are usually allopatric, in an area with early-stage invasion of sika deer into Japanese serow habitat. The habitat selection and activity patterns of the two species were evaluated using camera traps. Both species were recorded in >25% of the same camera sites and showed similar selection tendencies for water resources. The Japanese serows selected steep slopes, whereas the sika deer selected areas distant from human settlements, resulting in low spatial overlap. Additionally, the Japanese serows were more active during the daytime, whereas the sika deer were active at the crepuscule. The observed spatial and temporal partitioning likely reduces their encounter rates, thereby minimizing possible interference competition. However, spatial and temporal overlaps between the two species are likely to increase as the density of sika deer increases, potentially resulting in a decline in the density of Japanese serows with smaller body sizes. Trapping for deer management should be focused on areas with gentle slopes, away from valleys and human settlements, to reduce the unintentional capture of Japanese serows.The Japanese serow (Capricornis crispus) and sika deer (Cervus nippon) in Japan are usually allopatric. However, a recent expansion in the distribution range of sika deer, combined with an increase in abundance, has resulted in an overlap of the distribution ranges of the two species. We examined the habitat selection and activity patterns of Japanese serows and sika deer using camera traps placed at 83 sites within a 210 km2 study area, where the distribution range of these two species has recently overlapped. Although both species were photographed throughout the study area, we observed a low spatial overlap between them. The Japanese serows selected steep slopes, and the sika deer selected areas far away from human settlements. In addition, the Japanese serows and sika deer exhibited temporal partitioning with diurnal and crepuscular activity patterns, respectively. The observed partitioning could be explained by differences in their species-specific habitat selections, rather than competition, because the photographic capture rate of the Japanese serows was not affected by that of the sika deer and vice versa. These partitioning behaviors are likely to reduce the rate of encounters between the two ungulates, which enables their coexistence considering the sika deer density remains low.

In 1980 and 1981, eight and nine individual sika deer Cervus nippon were reintroduced in southern Hokkaido, Japan, respectively, to address population declines in this species during 1900s. As recent population growth has led to human–wildlife conflicts, this study investigated the responses of sika deer to resource availability and geomorphic factors during the summer and winter seasons in southern Hokkaido. Global positioning system‐collared data collected from 2016 to 2018 were used to assess the home range patterns and habitat selection of 14 female sika deer located in Mount Esan and Shiriuchi. The core home range size was defined using a 50% kernel density estimation that indicated a larger home range in winter than summer for all deer. Habitat selection was assessed using generalized linear mixed models. The results showed variation in habitat selection between resident deer of Mount Esan and Shiriuchi, as well as migratory deer in Shiriuchi during summer. Resident deer in Mount Esan and Shriuchi preferred areas closer to crops during summer. Interaction effects revealed that migratory deer utilized natural grassland close to forest edge habitat in Shiriuchi. By contrast, resident deer in Shiriuchi selected forest edge habitat and natural grasslands close to crops. In winter, low elevation was the most important habitat factor for all deer across the study area. Thus, sika deer habitat selection depends on resource availability in summer and topographic factors in the winter.

Two ruminants, sika deer (Cervus nippon) and Japanese serows (Capricornis crispus), inhabit the Japanese archipelago. The range of sika deer includes nearly the entire archipelago from Hokkaido to Kyushu, including habitats from the coastal zone to the montane zone. In contrast, the distribution and the habitat of Japanese serows are limited: they inhabit deciduous broad-leaved forests from Honshu to Kyushu (Ohdachi et al. 2009). These two ruminants occur in sympatry in some localities. Information on such cases would help to document how two animal species within the same guild can share a common food supply. However, only one study at Mt. Yatsugatake, central Japan, has compared the diets of sika deer and serows (Kobayashi and Takatsuki 2012). Their study demonstrated that sika deer subsisted on dwarf bamboo, whereas serows mainly fed on forbs and browses (Kobayashi and Takatsuki 2012). The diet compositions of the two species were more similar in winter, likely because food was limited and both ungulates were forced to feed on similar food plants (Kobayashi and Takatsuki 2012). Although it is known that there are many more sympatric populations of these two ruminants, no other studies have been done. Further, quantitative food analyses of Japanese serows are limited, and no study has been done for southern serow populations. The present study, therefore, compares the diets of sympatric populations of these two ruminant species in the eastern part of Shikoku, an island in western Japan, representing

Red and sika deer in the British Isles, current management issues and management policy

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Home range of sika deer (Cervus nippon) in coniferous plantation of Mie prefecture

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