Changes in geographical distributions of six species of medium and larger mammals in southern Izu Peninsula, Shizuoka Prefecture, central Honshu, Japan, were surveyed in 2003 by interviewing 432 residents and reviewing historic documents. This area (584 km²) is inhabited by 82,397 residents, and over 80% is montane and forested. Archives from the Edo period (prior to 1868) report wild boar (Sus scrofa) and sika deer (Cervus nippon) as nuisances and a bounty was paid for their skins, but only rarely mention grey wolves (Canis lupus), "yamainu or feral dogs" and the Japanese monkey (Macaca fuscata) as nuisances. Interviews and documents indicate that between the Meiji era (starting 1868) and World War II, populations of wild boar, sika deer and Japanese monkeys plummeted, and that grey wolves, Japanese black bear (Ursus thibetanus) and Japanese serow (Capricornis crispus) were eradicated, probably by heavy hunting. Post-war wild boar numbers increased steadily and nearly saturated the area in the 1990s. Japanese monkeys and sika deer followed the same pattern, inhabiting around 60% of the study area after 2000, resulting in heavy damage to agricultural crops. The recent decline of the local human population and primary industry may be offering these animals favorable conditions to increase.

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We investigated the environmental conditions of Alnus japonica forests as Neozephyrus japonicus habitat along the Arakawa-River, Saitama Prefecture, in 2004 and 2005. N. japonicus was observed in 40 of the 87 forests (46.0%). We measured 11 microhabitat characteristics in each forest and compared them to determine the specific requirements of the butterfly. A. japonica forests inhabited by the butterfly were younger, and the total stem diameter and coverage of flowering plants in June and July were larger than those not inhibited. This suggests that younger trees are suitable for larval growth and that flower abundance in June and July is an important factor. Significant negative correlations were detected between average tree age and total stem diameter and coverage of flowering plants, suggesting that more flowering plants are found in younger forests. This also indicates that younger forests are more suitable for the butterfly. The younger A. japonica forest has more flowering plants than mature forest edges. To conserve and maintain butterfly habitat, we recommend that A. japonica trees be cut down periodically and allowed to regenerate. This approach can be expected to promote young A. japonica forests with many flowering plants, suitable for both the larvae and adults.

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We surveyed the vascular flora on the Nakanoshima Islands in Toya Lake, Hokkaido, Japan, during the years 2002-2004. Here, the impacts of an excessive population of sika deer (Cervus nippon Temminck) have lasted for more than 20 years. The present survey found 150 plant species in 68 families on the islands (excluding the species recorded only in the areas impossible for the deer to enter), a decrease to 32.6% of the 460 species surveyed in 1977. The survival ratios of herbaceous, shrub and tree species were 18.8% (n = 67), 35.0% (n = 14), and 62.5% (n = 40), respectively. The survival ratios of herbaceous and shrub species were lower than for tree species. These results suggest that shrub and herbaceous species, which utilize the same space as deer, were more affected by the deer compared to the tree species. Numbers of alien plants did not change since the first survey, and the failure to increase was probably because of heavy foraging pressure. In recent years, deer have started foraging on unpalatable plants such as Cephalotaxus harringtonia var. nana and Senecio cannabifolius. The current findings suggest that the flora on the island change rapidly in response to pressure from browsing deer.

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