Artificial barriers, such as dams, diversion weirs, culverts, and the bases of bridges, prevent aquatic animals from migrating to upstream habitats. The barrier effect is serious for freshwater fishes that must swim to migrate, and isolated populations may become locally extirpated. In this study, we assessed the effect of habitat fragmentation by artificial barriers on the habitat distribution of two stream-dwelling salmonids: white-spotted charr, Salvelinus leucomaenis, and red-spotted masu salmon, Oncorhynchus masou ishikawae. We surveyed the distributions of presumed native populations in the Fujigawa Basin, Japan, by snorkeling along the stream and using a global positioning system (GPS) to record the points farthest upstream where fish were observed, as well as the locations of artificial barriers, from June to September 2004. In total, 356 artificial barriers have been constructed in the 29 surveyed streams (12.3 barriers per stream), and none of the barriers have fish ladders. Unfortunately, some isolated populations of both species have been locally extirpated, although both had occurred throughout the headwaters during the 1970s. Moreover, the number of streams in which charr and salmon coexist has decreased from five to one over a 30-year period. Multiple logistic regression analysis was conducted to examine whether seven variables were related to the probability of the occurrence of a fish population above the artificial barrier farthest upstream. The result suggests that the probability of the occurrence of salmon was lower than that for charr, and disappearance increased with decreasing watershed area (i.e., habitat size) above the artificial barrier farthest upstream, with increasing numbers of artificial barriers in the stream. According to this model, the estimated watershed area necessary to maintain a population is 1.01km^2 for charr and 2.19km^2 for salmon, suggesting that the probability of extirpation is very high if artificial barriers are constructed upstream in these watershed areas.

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Kirikuchi charr, Salvelinus leucomaenis japonicus, the southernmost population of the genus Salvelinus, is endemic to the Kii Peninsula, central Honshu, Japan. Kirikuchi charr are currently threatened due to anthropogenic disturbances. To conserve Kirikuchi charr, we investigated long-term population dynamics of Kirikuchi charr and red-spotted masu salmon, Oncorhynchus masou ishikawae, which share the same habitat, in the upper part of the drainage in the Totsu River system, Nara Prefecture, from August 1992 to September 2004. Population sizes showed a declining trend for both species; particularly after 2000, the population of Kirikuchi charr was approximately one-third of that in 1992. In 2004, the estimated number of salmon was approximately two times that of Kirikuchi charr. To evaluate the present population structure of both species, their population density and body size structure were investigated in 11 stream sections selected in the drainage. The majority of Kirikuchi charr were distributed in the upper part of the main stream and tributaries, and only a few fish were captured in the lower reaches of the main stream. In contrast, salmon inhabited the entire drainage without any obvious trends. Furthermore, almost all age-0 Kirikuchi charr were captured in the tributaries, whereas age-0 salmon were captured in the entire drainage basin. The average body lengths of Kirikuchi charr at age 0 and >1 were respectively smaller than those of salmon in all stream sections. These results suggest that salmon are competitively dominant over Kirikuchi charr. Based on the ecological evidence, we discuss conservation strategies for Kirikuchi charr.

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We investigated the structures of communities and populations of the component species in four stands of abandoned charcoal secondary forests that differed in the density of sika deer (Cervus nippon), to clarify the effects of herbivory by deer. Densities of stems in the lower height classes were markedly lower in stands affected by deer herbivory than in stands with no herbivory. In stands with herbivory, the effect of herbivory was not evident in Type I species that had a unimodal or flattened distribution in the upper height classes. However, in Type II species that had modes in the lower height classes, the patterns of stem height distributions changed from L-shaped to bell-shaped in the stands. Most late-successional species of tall trees were of Type II, and their saplings were sparse in stands affected by deer herbivory. This suggests that recruitment and regeneration of these species have been prevented in the stands due to herbivory by sika deer. If herbivory by deer continues over a long time in these stands, it may be difficult for the stands to maintain the framework of forest structure. On the other hand, stand regeneration may be attained by late-successional species of Type I. In this case, the future species composition of these stands should be determined through the processes of plagiosere succession, not by general secondary succession.

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Seasonal changes in paddy field and river foraging habitats used by herons and egrets were examined to determine the relative value of the two foraging habitats at the reintroduction site of the oriental white stork in Toyooka basin, Hyogo Prefecture, Japan. Herons and egrets gathered at the site to breed. Population size fluctuations were driven by changes in the paddy field; three times as many herons and egrets occurred in the paddy field than at the river. Therefore, it would seem that the herons and egrets depended on the paddy field for food during the breeding season, when the largest amount of food is required. During the non-breeding season, however, the majority of the herons and egrets did not forage in the paddy field, and particularly not in the rice ground. This suggests that the quality of the paddy field as a foraging habitat decreased during the non-breeding season, probably because the area had become dry. In contrast, the river provided a constant supply of food to the herons and egrets throughout the year. The river habitat may have been saturated with foraging herons and egrets, because their numbers did not increase during the non-breeding season, when they did not forage in the paddy field. It is necessary to increase the aquatic fauna of the paddy field during the non-breeding season for the success of this reintroduction.

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We developed a logistic regression model using spatial patterns to assess the risk of economic damage to crops caused by Japanese macaques (Macaca fuscata yakui) in two villages on Yakushima Island, Japan. Three explanatory variables were selected to assess whether an orchard was at risk of economic damage by macaques: the distances between the orchard and two geographical features (a forest and a busy road), and vulnerability to crop raiding, which reflects the difference in the likelihood of crop raiding by village. This model could be used as a basis for developing risk maps for economic crop damage by macaques. We discuss the effectiveness and limits of this model and suggest a possible risk map.

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To determine the origin of Florida largemouth bass (Micropterus salmoides floridanus) introduced into Lake Biwa, haplotype variation in the control region of mitochondrial DNA (mtDNA) of largemouth bass (Micropterus salmoides) was analyzed for 107 individuals from Lake Biwa and Lake Nishinoko (the Lake Biwa region), 39 individuals from Ikehara Reservoir, and 10 individuals from a fishery company that had previously cultivated Florida largemouth bass. Based on direct sequencing or single-strand conformation polymorphism (SSCP) analysis of the mtDNA control region, 3 haplotypes belonging to northern largemouth bass (M. s. salmoides) and 10 haplotypes belonging to Florida largemouth bass were identified. All four Florida largemouth bass haplotypes from the Lake Biwa region were also observed in Ikehara Reservoir. In contrast, all 10 individuals from the fishery company showed only one haplotype, which belonged to northern largemouth bass. Analysis of molecular variance (AMOVA) based on haplotype frequency indicated heterogeneity among populations within the Lake Biwa region. These results suggest that Florida largemouth bass of the same lineages as those found in Ikehara Reservoir were released multiple times in the Lake Biwa region.

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Researchers and volunteer citizens monitored the ratio of an alien bumblebee (Bombus terrestris) to a native bumblebee (B. hypocrites sapporoensis) and excluded this invasive alien bumblebee at Mukawa and Atsuma in the Hidaka Region of Hokkaido, Japan, from 22 to 23 May 2004. The number of participants was 36, and the total number of man-days was 90. Bombus terrestris was collected 603 individuals and B. hypocrites sapporoensis, 23 individuals, so the ratio of the invasive species increased about 30 times for only one year. The purposes of this action included decreasing alien B. terrestris populations, providing an opportunity wherein scholars and volunteer citizens could interact with each other, nurturing young volunteers, and obtaining the co-sponsorship of a private company. This type of cooperative research could be a very important step towards solving problems related to alien species, accelerating the participation of research volunteers, as well as deepening our understanding of alien species problems through the collaboration of scholars and citizens. Collaboration by scholars and citizens is a highly effective method for understanding alien species problems from the viewpoints of environmental education and sharing information.

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Fenthion is an organophosphate-based insecticide that is highly toxic to birds. Historically, fenthion was used to kill birds, and its usage is now prohibited or severely restricted in North America and Europe, partly due to its severe influence on ecosystems. However, in Japan, it has been used for a long time in a wide variety of environments, and people generally, including conservation biologists, have not noticed any toxicity to birds and other animals. The Ecological Society of Japan is concerned that more fenthion will be applied to natural habitats as a tool for extinguishing West Nile virus. Therefore, at its 52nd annual meeting in March 2005, the Society drafted a resolution banning the use of fenthion. The resolution document was then submitted to the Ministry of the Environment; the Ministry of Health, Labor, and Welfare; and the Ministry of Agriculture, Forestry, and Fisheries in April. The Ministry of Health, Labor, and Welfare quickly responded to our request and sent a notice to the relevant sections of central and local governments to refrain from using fenthion for West Nile virus and related purposes. In this report, we describe the process, purpose, and content of our request submitted to the government Ministries. We also note the reason why deleterious chemicals such as fenthion are still widely used in this country and offer suggestions on how to use chemical substances appropriately in ecosystems.

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Nature and wildlife observation is a popular activity that attracts many people. From the viewpoint of conservation ecology, it is important to know the effect of such human activity on the wildlife concerned. The giant flying squirrel (Petaurista leucogenys) is a recent, popular subject of observation in Japan. Yakuo-In Temple in Takao, Tokyo, is a renowned location for the observation of giant flying squirrel. However, the observation of this species at the temple only became popular in the mid1990s. Observation records made by a high school club revealed that giant flying squirrel in Yakuo-In departed their nests 30 min after sunset in 1987-1998; here, we report nest departure data for 2003-2004. Giant flying squirrel that lived in a highly visited nature-observation area departed their nests 60 min after sunset on average, whereas those that lived in a more secluded area departed their nests 30 min after sunset. Giant flying squirrel also departed their nests later when there were >20 observers near the nest. Thus, wildlife observation activity is responsible for the delay in the time of departure from the nest in giant flying squirrel.

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