Hybridisation between exotic species and closely related native species has become a problem in various taxa, and management of the resulting hybrids is urgently needed. However, by the time their existence has been confirmed, hybrids have often already increased in number and spread over wide areas, such that assessing their current status is a top priority. This study estimated temporal changes in giant salamander populations in the Kamo River in Kyoto, Japan to obtain basic knowledge necessary for the management of non-native species and hybrids. The native Japanese giant salamander (Andrias japonicus) is threatened by environmental degradation, habitat fragmentation, and population decline and loss of genetic uniqueness due to hybridisation with the non-native Chinese giant salamander (Andrias davidianus). Hybridisation is ongoing in the Kamo River, which was surveyed 134 times between 2005 and 2021. This study constructed a Bayesian state-space model based on these survey data to estimate the populations of Japanese individuals, non-native individuals, first-generation hybrids, and unknown hybrids. The results indicated that unknown hybrids currently constitute the main population in the Kamo River, while the numbers of native and pure non-native individuals are quite limited. At the beginning of the survey period, the population of first-generation hybrids was the largest, but unknown hybrids subsequently dominated, suggesting that most individuals deemed unknown hybrids were second-generation or later hybrids. The detection rate of individuals per survey was less than 0.1%, indicating that the current survey method is ineffective for population control. Furthermore, the survival rates of native, non-native, and first-generation hybrid individuals declined during the survey period, suggesting that they are aging. These results indicate that the management of non-native and hybrid giant salamanders requires limiting target areas and adopting more efficient control methods.

In recent years, green infrastructure (GI), an approach that actively leverages natural environments for societal development, has gained increasing attention. A key component of this is ecosystem-based disaster risk reduction (Eco-DRR), which utilises ecosystems as disaster-prevention infrastructure and has been adopted as an administrative policy in many regions. GI seeks to integrate ecosystems into human society as functional infrastructure, making societal systems critical to its implementation. This study investigates the factors that promote Eco-DRR-related GI projects within local administrations. Drawing on data from basic land-use plans and a nationwide survey of local governments, we examined project implementation, land-use category ratios, and the positioning of GI within administrative plans. Statistical analysis of responses from 673 municipalities revealed that those with substantial forest and agricultural areas in their land-use plans were more likely to implement Eco-DRR-related GI projects tailored to those environments. In contrast, municipalities with predominantly urban land use tended not to pursue GI projects for urban areas, likely due to the higher costs of installing artificial structures compared to leveraging existing ecosystems. Administrative planning also played a pivotal role. The inclusion of GI within comprehensive plans was associated with increased project implementation, regardless of the target area. Additionally, other administrative plans showed potential for the promotion of GI projects aligned with specific land-use categories. These findings suggest that both land-use composition and administrative positioning are key drivers in advancing Eco-DRR-related GI initiatives.

Flower-visiting insects are essential for the pollination of both wild and cultivated plants, but their populations have declined due to global environmental changes caused by human activities. Conservation of flower-visiting insects is therefore a pressing issue internationally that has led to conservation activities and conservation-directed ecological research worldwide, including in Japan. However, very few Japanese-language textbooks and review articles comprehensively introduce the methods used to conserve flower-visiting insects in Japan, and the materials necessary to conduct local conservation activities are lacking. In this paper, we provide a summary of the comprehensive conservation methods that have been developed for flower-visiting insects, mainly in Japan. Three topics are introduced: conservation methods in forest, agricultural and urban landscapes, as the main habitats of flower-visiting insects; actions against sika deer, which have caused catastrophic damage to nectar-providing plants and flower-visiting insects in recent years; and methods for restoring the habitats of flower-visiting insects and nectar-providing plants. For methods lacking research carried out in Japan, such as the use of bee hotels in the restoration of flower-visiting insects’ habitat, research conducted overseas is introduced, as appropriate. Given the increasing threat to flower-visiting insects, research in areas for which knowledge is still scarce should be promoted. Conservation and restoration methods should also be developed and their effectiveness verified.

Predation by the common raccoon (Procyon lotor) is among the most serious causes of native biodiversity loss in Japan. On the Boso Peninsula in Chiba Prefecture, population declines in the endemic Japanese pond turtle (Mauremys japonica) have been attributed to P. lotor since 2008. Because P. lotor predation on M. japonica occurs mainly during winter, identifying and managing the overwintering habitat of M. japonica is essential for reducing this predation pressure. We conducted a capture–recapture survey of M. japonica in a creek invaded by P. lotor on the Boso Peninsula. The main overwintering habitat for M. japonica was identified as shallow water with a mud bottom and overhanging wild rose bushes (Rosa multiflora). However, these rose-covered shallows have increasingly disappeared while the estimated population size of M. japonica has decreased, which suggests that these shallows act as shelters that reduce predation pressure by P. lotor. In addition to eradicating P. lotor and conducting long-term monitoring, overwintering habitats should be created to reduce predation pressure on M. japonica.