Abstract: Assessing the risk of collisions between wind turbines and passing birds is an important issue in bird conservation. Unlike their larger counterparts, small wind turbines do not need to undergo environmental impact assessments (EIAs) in Japan. Being subject to fewer restrictions, they can be constructed where large turbines may be forbidden. Small wind turbines are increasingly being installed in Japan, and the endangered white-tailed eagle (Haliaeetus albicilla) is known to collide with them. As EIA methodologies are geared toward large turbines, they may be unsuitable for small turbines. However, there has been no formal assessment of the risks of bird collisions with small wind turbines in Japan. In the absence of systematic collision data, we used bird flight frequency near small turbines as a proxy for collision frequency. We recorded birds flying within 10 or 20 m of small wind turbines during point-count surveys and then ran generalized linear models with the number of flights as the objective variable and weather and surrounding land cover as explanatory variables. Slaty-backed gulls approached turbines most often (537 observations), followed by black-tailed gulls (536), large-billed crows (459), and Oriental greenfinch (292). Two rare species, the white-tailed eagle and Steller's sea eagle, were recorded 29 and 2 times, respectively. The slaty-backed gull is also the species most often observed colliding with large wind turbines; small turbines seem to also be approached by smaller grassland species. The effects of wind speed varied, with three species flying less during high winds and white-tailed eagles flying more. All species regularly approached within 10 m during their breeding seasons, indicating that these are periods of especially high collision risk. Given the small number of survey sites in our study, our results provide only preliminary insight into turbine placement and bird collision risk management; more research is needed.

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Abstract: In Japan, Pallas’s squirrel (Callosciurus erythraeus) is an invasive species that was introduced from its native range in Southeast Asia through human activity. Using liver tissue samples obtained from C. erythraeus specimens collected from 2018 to 2022, we investigated the genetic structure of this invasive species in the cities of Kamakura, Yokohama and Yokosuka in Kanagawa Prefecture, Japan. Genomic DNA was extracted from each individual, and nucleotide sequences of the mitochondrial cytochrome b (cyt b) and D-loop regions were subjected to polymerase chain reaction and direct sequencing analyses. The cyt b sequence (1080 bp) analysis successfully identified 28 haplotypes (from 214 individuals) that were separated into three clades, all of which appear to have originated from Taiwanese populations. We subsequently identified the geographical origin of the three cyt b clades using D-loop sequences for which data were accumulated within their native range. For each cyt b clade, 38 representative individuals were selected and investigated their D-loop sequences (1079–1080 bp). The results showed that these representatives belonged to three native C. erythraeus populations in Taiwan: the eastern and western populations, and a population that was previously described as unknown, but sister to the eastern and southern populations. All haplotypes of this latter group were found in southern Taiwan. We classified all cyt b haplotypes from our sampling area into the three identified lineages and analysed their lineage distribution. In Kamakura, the eastern lineage and its sister group were mixed, suggesting two previously described introduction routes. In one pathway, pets escaped from a private owner in Kamakura prior to World War II; in the second pathway, individuals were introduced onto Izu Oshima, an island off Tokyo, and later transported to a botanical garden in Enoshima, from which they escaped in the 1950s. In Yokohama, the western lineage was intermixed with the eastern group and its sister group. In the eastern group and its sister group in Yokohama, however, haplotype composition was different from those in Kamakura, implying a complicated history of multiple introductions through different routes, other than those detected in Kamakura. Both lineages observed in Kamakura were also detected in Yokosuka; however, singleton haplotypes were more often observed in the latter city than former, suggesting a history of unrecorded introductions into Yokosuka. These findings will be useful for developing an effective control plan and preventing distribution expansions for this invasive mammal species.

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Green infrastructure and ecosystem-based disaster risk reduction (GI/Eco-DRR) policies have recently attracted attention in Japan for their potential to resolve various social pressures such as regional economic development, disaster prevention and mitigation, and environmental conservation. Past studies of policies related to the natural environment have mainly investigated changes in biodiversity-related administrative plans, policies, and projects led by national and local governments, and the status and effects of their implementation. However, few such studies have examined municipal GI/Eco-DRR administrative plans, policies, and projects in Japan at the national scale. Therefore, this study conducted a nationwide survey of municipal officials regarding their awareness of GI/Eco-DRR administrative plans and the implementation of related projects. The results revealed that the role of GI/Eco-DRR in administrative plans differs according to the type of plan, and that the implementation of GI/Eco-DRR-related projects is influenced by the type of ecosystem in which the projects are implemented and the size of the local population. Staff awareness of green infrastructure tends to be higher in larger than in smaller municipalities, and larger municipalities are more likely to proactively incorporate GI/Eco-DRR into their administrative plans. Differences in the implementation status of GI/Eco-DRR policies among municipalities are attributable to factors such as the lack of information dissemination opportunities, specialised human resources, and financial resources, which are closely related to municipal population size.

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Abstract: Unmanaged bamboo forests are spreading in several parts of Japan. Bamboo forests tend to have low plant species diversity due to the lack of sunlight. Gastrodia pubilabiata Y. Sawa and G. confusa Honda et Tuyama, which are threatened plants in Japan, are often found in bamboo forests. Both species are mycoheterotrophic plants and theoretically grow in dark environments, along with their symbiotic fungi. Previous studies have suggested that G. pubilabiata and G. confusa prefer forest understories that do not fully cover the vegetation. This environmental condition may match the understories of bamboo forests. In this study, we tested the hypothesis that bamboo spread has created a long-term stable forest harbouring G. pubilabiata through the establishment of a dark environment with little vegetation cover. We focused on G. pubilabiata as there has been minimal misidentification among recently collected specimens. We collected specimen records for the Kanto region of Japan, and established a land cover map using a time series of aerial photographs of the surrounding region for analysis. We also conducted a field survey of G. pubilabiata and analysed its local environmental conditions. Our analyses of the specimen records and field surveys showed that G. pubilabiata inhabits a bamboo forest within the long-term stable forest. Our findings suggest that bamboo forests can harbour this threatened plant species depending on the local conditions. Although we were only able to evaluate this role in the short term, our results suggest that bamboo forests can have positive effects on regional biodiversity. Therefore, the role of unmanaged bamboo forests in the conservation of regional biodiversity should be reconsidered.

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Abstract: Recently, the distribution of the Channel Catfish, Ictalurus punctatus, an invasive alien species, has been expanding in several water systems in Japan. The species’ first occurrence in the Yahagi River was confirmed in 2005. Since then, a local institute and citizen groups have conducted collection surveys to eliminate the species, catching over 100 individuals in the middle reaches. However, no surveys of the species have been conducted in the river since 2015; therefore, its current status is unknown. Additionally, although several occurrence records of the species in the river have been published, including progress reports of the collection surveys, the contents and accuracy of information provided in these documents vary, with some discrepancies in descriptions that appear to refer to the same occurrence record. To eradicate the species, it is essential to assess the reliability of individual records, incorporate differences among them, and estimate the species distribution before planning a control program. This study used the following four methods to collect information about the spatial extent of the species’ occurrence (i.e., captures and sightings) in the Yahagi River system: (1) a literature review; (2) information collected in public databases; (3) re-examination of previous collection survey data; and (4) information collection targeting the public (e.g., residents and anglers). The database search covered the River Environmental Database, which collects data from the National Census on River and Dam Environments conducted by the Ministry of Land, Infrastructure, Transport, and Tourism (MLIT). To collect information from the public, leaflets and cards calling for information on the species were designed and distributed; face-to-face and online interviews were conducted. Based on the information obtained, we have confirmed reliable occurrence records for 122 individuals collected in the area from the Azuri Dam reservoir (Toyota City, Aichi Prefecture, approximately 53 km upstream from the river mouth) to the backwater of the Meiji Weir (35 km upstream from the river mouth). Fourteen of these individuals (12%) were provided by citizens (e.g., fishermen and anglers). Capture records and sighting reports (with relatively low reliability) were collected in the area from the Yahagi Dam reservoir (approximately 70 km upstream from the river mouth) to the Yahagi-Furukawa River branching point (Nishio City, Aichi Prefecture, 13 km upstream from the river mouth). Obtained occurrence information was concentrated in the middle part of the river, likely due to sampling bias. Therefore, a systematic quantitative survey over a wide area at multiple sites will be required to identify the species’ distribution range in the future.

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Abstract: The rivers that the endangered Sakhalin taimen, Parahucho perryi, currently inhabits, or inhabited historically, and catch records therein are relatively well known. However, there are no data on long-term population-size estimates of this species in Japan, making it difficult to assess their extinction risk and to formulate and implement effective conservation measures. In the spring of 2023, a 23-day fish-monitoring program using an underwater acoustic camera in the upper reach of the Karibetsu River, a tributary of the Sarufutsu River in the Soya Hills, Hokkaido, Japan, detected 315 fish during their spawning migration upstream. Based on footage from an optical video camera installed on the riverbank, used as training data, the detected fish were predicted to comprise 139 Sakhalin taimen; 23 masu salmon, Oncorhynchus masou; and 153 Tribolodon species. The estimated number of spawning Sakhalin taimen was roughly 30–40% of estimates obtained in 2013–2015, implying a significant population decline over the past decade. Die-off of Sakhalin taimen resulting from the record-breaking heatwave that hit this region during the summer of 2021 is suspected to be the direct cause of the drastic population decline. The southern part of the Soya Hills, including the Sarufutsu River Basin, is undergoing rapid wind-power development, necessitating urgent establishment of monitoring protocols to assess the impact of large-scale developmental projects on Sakhalin taimen populations. The use of acoustic cameras, which enable quantitative, efficient estimation of fish populations and non-invasive long-term monitoring, should contribute to effective conservation of this endangered freshwater fish.

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Abstract: The diet composition of sika deer (Cervus nippon) in Kyushu, Japan, has been poorly studied to date. Therefore, we analysed the seasonal diet composition of sika deer in the Shiiba Research Forest of Kyushu University. The deer population has increased since the 1970s and the forest ecosystem has been heavily affected by deer browsing; for example, the broad-leaf bamboo (Sasa borealis) disappeared from the study area around 2000. Faecal composition analyses of samples collected in 2022 and 2023 showed that fibre and culm were predominant, with green leaves accounting for only about 30% of the sika deer diet even in summer; thus, the deer appear to consume poor-quality food throughout the year. A comparison of the diet composition of sika deer in the study area with those of other habitats throughout Japan during the 2000s suggested that they had a very poor diet, probably because of deterioration of forest floor vegetation as a result of heavy deer browsing during the last few decades.

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The Ichinomiya Canal is an irrigation and drainage channel, lined with two- and three-sided concrete revetments, that flows through paddy fields alongside the Tama River in Tokyo, Japan. The progressive collapse of these revetments in various sections of the canal prompted a construction project in early 2014. To enhance biological habitats associated with the canal, various improvements were undertaken, including a timber piling revetment constructed on one bank (section I-3), and lowering of the canal bottom by 30 cm beneath a bridge that spans the canal (section I-2). A preliminary larval survey was conducted in November 2013 (immediately before construction began). Between 2014 and 2021, with the aid of public participation, four canal sections were surveyed to determine the effects of the improvements on dragonfly populations. The target area extended from upstream (section I-4) to a downstream section where Iris pseudacorus L. had been planted along one bank (section I-1); sections I-1 and I-4 had been lined with two-sided concrete revetments during previous repair works. In all sections, we recorded the numbers of each species of dragonfly larvae, as well as various environmental parameters. The surveys identified a total of nine dragonfly species belonging to six families in all sections combined. Comparisons of each section after construction revealed that overhanging plants thrived better in section I-3 than in section I-4, and that Orthetrum albistylum speciosum and Shaogomphus postocularis were more abundant in section I-3 than in the other sections. In sections I-3 and I-4, sand and mud covered the canal bottom and submerged plants thrived; in section I-2, mud and leaf litter covering the bottom maintained a gentle, stable aquatic environment that led to greater abundance of Sieboldius albardae and Macromia amphigena amphigena than in the other sections. Anax parthenope julius, Ischnura asiatica, and Atrocalopteryx atrata were more abundant in section I-1, where Iris pseudacorus L. was planted on one bank, than in the other sections. In section I-3, the larvae of only one species, Orthetrum albistylum speciosum, were observed in November 2013, prior to canal improvement, whereas surveys conducted between 2014 and 2021 recorded six species of dragonfly larvae belonging to five families, following the construction of timber piling revetments. Water flow velocity and depth, litter and mud depth, and vegetation cover differed significantly among the surveyed sections. This environmental diversity along the canal may have a complex relationship with dragonfly species diversity. Our findings demonstrate the effectiveness of continuous monitoring with the aid of public participation.

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Abstract: Mt. Hiuchi, in Niigata Prefecture, central Honshu, Japan, lies at the northern range limit of Japanese rock ptarmigan, Lagopus muta japonica. The rapid growth of gramineous plants in the area has reduced the forage available to Japanese rock ptarmigan, and a project to remove these plants is ongoing. To determine the effectiveness of these efforts, it is necessary to characterise how Japanese rock ptarmigan use available forage species. To identify forage plant use at Mt. Hiuchi, we conducted DNA metabarcoding of the rbcL gene on 96 ptarmigan faecal samples from May-July and October, 2019. The resulting sequences were analysed against a combined database of 136 species derived from samples collected from Japanese rock ptarmigan habitats, and the National Center for Biotechnology Information (NCBI). In all, we found evidence of 40 taxa, of which 32 could be identified to species, 4 to genus, 3 to family and 1 to order. Based on rarefaction and extrapolation sampling curves using the exponential of Shannon entropy, we estimated that 98.2% of available forage taxa were sampled over the study period. Of the 12 plant families represented in the combined database, the most foraged were the Apiaceae (found in 62.5% of faecal samples), followed by the Saxifragaceae (53.1%), Ericaceae (52.1%) and Rosaceae (50.0%). In the faecal samples examined, the most frequently encountered plant species were Ligusticum holopetalum (38.5%), Rubus vernus (38.5%), Tiarella polyphylla (37.5%), Micranthes fusca var. kikubuki (36.5%) and Alnus alnobetula subsp. maximowiczii (30.2%). The high foraging frequency of plants in the Apiaceae and Saxifragaceae at Mt. Hiuchi is anomalous among Japanese rock ptarmigan habitats, indicating high local specificity. Our survey further supports the potential of the gramineous plant removal project, to contribute to the restoration and conservation of major ptarmigan forage species. The major forage plants in this area grow around the summit of Mt. Hiuchi and along the margins of Pinus pumila and Alnus alnobetula subsp. maximowiczii communities. Therefore, the growth and expansion of these tree species—and the associated loss of marginal habitat—may also reduce the quality of the feeding environment for Japanese rock ptarmigan. Controlling these tree species should also be considered, along with the continued removal of gramineous plants.

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Abstract: We used faecal analysis to assess the diets of sika deer from Tobihino Park and Kasugayama Forest Reserve (KFR) in Nara, Japan. In Tobihino Park, the lawn grass Zoysia japonica was an important food source from spring to autumn, whereas higher-fibre foods were consumed in winter. In the KFR, deer consumed mostly fibrous foods and other unidentified materials (seed fragments, bud scales, etc.), and leaves formed a relatively minor part of their diet, even in summer. These differences reflected the understory plant communities of the respective sites. Deer from the KFR mostly consumed plants endemic to the forest, impacting forest structure and regeneration. These results highlight the challenges inherent in balancing the maintenance of “park deer” and the conservation of forests around the KFR.

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Abstract: In this study, we examined hydro- and hygrophytic vegetation in small, seasonal wetlands along the shoreline of the Taguchi Oohora Pond, an irrigation reservoir constructed ~130 years ago in Inuyama, central Japan. Traditional rice cultivation practices in the region intermittently but significantly reduce the water level of the reservoir. During these irrigation periods, submerged shoals are transformed into sand and gravel wetlands. These shoals formed through the abundant supply of friable deposits from the geological features of the watershed, and because the reservoir is no longer dredged to maintain the water capacity. Few reservoirs in the area exhibit this type of wetland formation, as water levels are increasingly maintained by water supplied from rivers or other reservoirs via irrigation channels that cross catchment boundaries. We identified over 100 hydro- and hygrophytic taxa, including eight endangered species, in the target reservoir and nearby wet environments including riversides, rice fields, and low-lying swamps, both up- and downstream from the target reservoir. Given the transitional nature of these habitats, it is uncertain whether the plant species observed in this study will persist. In local communities, discussions have just started regarding stopping vegetational succession at a desirable stage to preserve endangered species or to maintain species diversity. The associated problems are common to many substitutional conservation sites.

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Abstract: The conservation of cave-dwelling bats can be improved by prioritization of cave habitat. We surveyed 119 caves in Chiba Prefecture, Japan to determine bat presence and evaluate the caves’ conservation priority value. Using a cave biotic potential (BP) index, which was based in part on bats’ relative abundance, we classified the caves as levels 1–4, where Level 1 indicated the highest priority for conservation. Cave surveys were completed over four seasons, inclusive of nursery and hibernation periods. In total, four bat species (Rhinolophus nippon, R. cornutus, Myotis macrodactylus, and Miniopterus fuliginosus) were confirmed to inhabit 70 of the surveyed caves. Fifteen caves were classified as Level 1 within at least one survey season. In addition, the first nursery cave of M. fuliginosus in Chiba Prefecture was identified, containing 16,331 bats. This cave is likely critical to maintaining the population of M. fuliginosus in Chiba Prefecture. For R. nippon, of 10 nursery caves identified, only one was classified as Level 1, with one additional cave classified as Level 2. Given that R. nippon form small nursery colonies, the BP index, which is strongly influenced by abundance, may underestimate the conservation value of caves inhabited by this species.

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Abstract: The herbaceous vegetation layer in urban parks provides ecosystem services that include places for people to sit on the ground, prevention of mud and dust formation, prevention of soil erosion, and flood prevention via increased rain infiltration. Species composition in green spaces in urban areas varies owing to differences in their histories. In newly developed parks on reclaimed land, shade-tolerant native species that grow on the forest floor in ‘satoyama’, or remnant vegetation, may be absent from the species pool, leading to concerns that the ecosystem services of the forest-floor vegetation may be degraded. In this study, we measured the ecological traits of the species pool (shade and trampling tolerance at the species-pool level) in various parks, and analysed their effects on the ground-surface leaf area index. Because trampling also affects vegetation in parks, we used soil penetration-resistance values to account for its effects. A lack of shade-tolerant species in the species pool reduced the leaf area index of forest-floor plant communities. The shade-tolerant species detected in our surveys included native species such as Houttuynia cordata, Ophiopogon japonicus, Oplismenus undulatifolius, Paederia foetida, Pleioblastus chino, and sedges. Species pools in parks with ‘satoyama’ typically included these species. Species pools containing shade-tolerant native species are important for improving ecosystem services beneath tree canopies, and we recommend conserving historical ‘satoyama’ to prevent the loss of native shade-tolerant floras when renovating or creating parks.

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The construction of solar power generation plants in the Kushiro wetlands has led to loss of habitat for the endangered Siberian salamander (Salamandrella keyserlingii), and effective conservation measures are urgently needed. At the request of the solar power producers, the Siberian salamander habitat within the project site was surveyed. The results showed that a broad area within the project site was inhabited by this species, necessitating conservation measures. The solar power producers agreed to the proposed conservation measures, which included translocation of salamander egg sacs. The following points were considered for implementing conservation by translocation of egg sacs: selection of translocation destinations, selection of individuals to be translocated, consideration of genetic disturbance, and selection of translocation sources. Over a 4-year period, during both construction of the site (2018–2019) and after its opening (2020–2021), egg-sac surveys were conducted annually across the project site, and egg sacs were continuously transported to waters in the southwest area of the project site. A final egg-sac survey was conducted in the translocated water area in 2022. The results of the surveys showed annual reductions in the numbers of spawners across the project site from 2018 to 2020. However, the numbers of spawning sites and spawners increased in 2021, the second year of operation of the facility, likely due to increased spawning by surviving subadults and adults as the habitat recovered and stabilised. The 2021 survey, which was conducted following egg-sac translocation, recorded 333 egg sacs in the translocated water area, representing a ca. three-fold increase compared to 2020 (107 egg sacs), likely through the reproductive activity of both males and females derived from egg sacs relocated in 2018. In the 2022 survey, 282 egg sacs were recorded, again representing a ca. three-fold increase compared to 2020. Thus, the numbers of egg sacs increased significantly over time. No significant relationship was detected between precipitation during the breeding season and the numbers of egg sacs in the translocated water area, indicating that precipitation was not responsible for the observed increases in egg-sac numbers, and that translocation efforts in 2018 and 2019 were effective. This study and previous studies have demonstrated the efficacy of translocating a portion of a Siberian salamander population over a time scale of several years (beyond the age at which individuals begin to reproduce). However, achieving successful population translocation over time scales from 5 years to several decades (beyond the life span of individuals) will require continued monitoring and clarification of the determinants of Siberian salamander population density in the field.

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