We investigated temporal changes in the body size of loggerhead turtles, Caretta caretta, nesting on Yakushima Island, Japan, and examined whether body size varied during the nesting season. Our results showed that the straight carapace length (SCL) of females nesting between 1999 and 2005 was significantly smaller than that of females nesting between 1985 and 1991, and the overall size distribution shifted toward a greater proportion of smaller individuals and a marked decrease in larger individuals. Analyses of the lower and upper tails of the SCL distribution also indicated significant reductions in both extremes. In the later period, several size classes exhibited higher nesting frequency than the earlier period, suggesting that nutritional conditions in foraging grounds may have improved, potentially contributing to higher nesting frequency. Smaller individuals tended to nest later in the season in both study periods, with first nesting dates significantly delayed for females within the lower tail. This seasonal tendency may be influenced by differences in migration distance between large females using neritic foraging grounds in the East China Sea and small females relying on pelagic foraging grounds in the North Pacific. Taken together, our findings indicate substantial temporal changes in the size structure of the Yakushima nesting population. In addition, consistent seasonal patterns in nesting timing were observed.
The genus Gloydius currently contains at least 29 recognized species, widely distributed across diverse habitats in Asia, from east of the Ural Mountains to Japan. The Qinghai-Xizang Plateau and its adjacent areas represent a major center of diversity for this genus, with at least 20 species recorded. Gloydius swild, a recently described species, was originally based on only two female specimens collected from Heishui County, Sichuan Province, China. During recent field surveys, we collected additional specimens (four males and five females) from three localities in Heishui and Songpan counties, Sichuan, China. Integrative morphological and molecular analyses confirmed that these specimens are conspecific with G. swild. This study provides an expanded description, revised diagnostic characters, and new localities for this recently described species based on all available specimens.
Roads within protected areas can cause substantial mortality of amphibians and reptiles, yet quantitative roadkill data from tropical protected areas in Vietnam remain limited. We assessed amphibian and reptile road mortality in Ba Vi National Park, northern Vietnam, using systematic road surveys conducted during three periods between March 2024 and February 2025. Amphibians accounted for about half of all records but included fewer species, whereas reptile roadkills were more species-rich. Kernel Density Estimation outputs suggested that amphibian hotspots were relatively localized, whereas reptile hotspots were more extensive and dispersed. Seasonal patterns also differed between taxa. A significant interaction between taxon and seasonal phase was supported, with predicted amphibian roadkill counts highest during the sampled hot-rainy months (May and September) and reptile roadkill highest during the transitional months (April, October, and November). This study provides rare evidence from Vietnam and highlights the need for mitigation strategies targeted by taxonomic groups, road segments, and seasons, especially as protected-area infrastructure continues to support tourism and management.
Amphibians exhibit a wide range of overwintering strategies depending on environmental conditions. Accordingly, invasive species may adopt novel overwintering behaviors after being unintentionally introduced into regions that differ in climatic conditions from their native habitats. In South Korea, the American bullfrog (Aquarana catesbeiana), a major invasive species, has become widely established; however, information on its winter activity remains limited. To address this gap, this study aimed to document winter activity and home-range characteristics of invasive A. catesbeiana in South Korea to improve ecological understanding and inform management strategies. Using radiotelemetry, five adult individuals were tracked for approximately three months during winter. Although most individuals were not directly observed field during surveys, telemetry signals indicated limited but continuous movement throughout winter. Based on estimated locations, the mean winter home range (minimum convex polygon) was 1,089.0 m2. Individuals were primarily distributed along pond shorelines, characterized by shallow water and stable aquatic vegetation. These findings provide baseline field data on winter activity and spatial use of A. catesbeiana in South Korea, contributing to a better understanding of the overwintering ecology of this invasive species in temperate regions.
The global decline in amphibians, particularly frogs, has raised concerns because of their ecological significance and sensitivity to environmental changes. Satoyama, a traditional 'socio-ecological production landscape,' has been rapidly decreasing, and many paddy-dominated landscapes in developed and developing Asian countries are in transition due to urban and industrial development. The objectives of this study were: 1) to create potential distribution maps of frogs throughout Tsukuba City, which consists of diverse landscapes, including forests, rice fields, and urban areas, using a species distribution model with four environmental variables (land-use, distance from the river, slope, and elevation); 2) to assess the importance of Satoyama for and the impact of urbanization on local frog conservation; and 3) to contribute to regional biodiversity conservation planning in areas undergoing urbanization. In total, 872 presence data were recorded from six native and two invasive frog species during field surveys conducted between 2021 and 2024. According to the species distribution model, land-use was often the most important factor for many species, with either rice fields or forests being the preferred sites, whereas urbanized areas (building sites) negatively affected all species. Other environmental variables were also predicted to be important variables depending on the species, but all species that were affected by distance from the river had a higher distribution probability near the river. Our results demonstrate the negative impact of urbanization on the distribution of frogs and on Satoyama landscapes, where water-supplied rice fields and rivers intermingle with forests, which are important sites for the conservation of many frog species.
