To establish practical criteria for assessing the nutritional status of Asiatic black bears (Ursus thibetanus) in the context of wildlife management, we re-evaluated previous findings by expanding both sample size and study duration. Nutritional indicators—including modified kidney fat index (mKFI), subcutaneous fat thickness (SF), femoral marrow fat (FMF), and body condition index (BCI)—were collected from deceased individuals. We examined their variation across age classes, sex, and seasons. Results showed that mKFI, SF, and BCI exhibited clear seasonal trends and were effective for evaluating nutritional condition using simple measurements. Among four SF measurement sites, the ventral pelvic region was the most reliable for indicating subcutaneous fat. All three indicators (mKFI, SF, and BCI) were higher in females than in males. However, an interaction between age and sex was found for mKFI, suggesting potential effects of reproductive activity. BCI values in females were lower in those with dependent offspring, likely due to the energetic costs of lactation and maternal care. With increasing hunting pressure, monitoring the nutritional status of harvested individuals will be crucial for tracking population dynamics. These indicators may serve as useful tools for predicting habitat quality and population trends through nutritional monitoring.

Siberian weasel (Mustela sibirica) is an introduced species in Honshu, one of a Japanese mainland. In early 2000, Siberian weasel was not thought to expand eastward beyond Aichi prefecture, where the Japanese weasel (Mustela itatsi) inhabits. However, this biological regulation hypothesis has not been evaluated so far, thus recent distribution of Siberian weasels in Aichi prefecture needs to be evaluated. In this study, we collect roadkilled weasels to evaluate the distribution of both Siberian and Japanese weasels in Okazaki city, Aichi prefecture, that includes a border area from urban to forest areas. In the thirty-seven roadkilled weasels collected from November 2020 to October 2021, twenty-one weasels are identified to Siberian weasels, and fifteen weasels are identified to Japanese weasels, and the other one is unidentified. When the recovery sites of individuals with available location data were mapped, the distributions of the Siberian weasel and the Japanese weasel were biased toward the western and central parts of the city, respectively. Siberian weasels were predominantly recovered from residential areas, whereas Japanese weasels tended to be recovered from both natural forests. Preferred habitats predicted by a multinomial logistic model including both weasels with pseudo-false points suggest that Siberian weasels can expand along residential areas.

In Japan, where the forest coverage is high and the terrain is steep, there was no established methods for estimating density of wild boar (Sus scrofa), which are difficult to identify by appearance. In recent years, density estimation methods using camera traps without individual identification, the Random Encounter Model (REM) and the Random Encounter and Staying Time Model (REST), have been developed and are beginning to be used in category 2 specified wildlife control plan for wild boar. However, there have been no comparative studies of REM and REST targeting wild boar populations in Japan, and it is necessary to verify the practicality of these methods. Therefore, this study aimed to compare the estimated population size of REM and REST in an isolated wild boar populations in Gifu Prefecture. We installed 20 infrared triggered cameras from October to December in 2020 and 2021, and estimated population densities by both methods. The median population estimates in 2020 and 2021 using conventional REM, REM using REST’s effective detection zone, and REST were 21 and 9, 122 and 41, and 101 and 53, respectively. Considering the number of captures in this study area, the density estimated by conventional REM is an underestimate, and it is important to define the effective detection zone. On the other hand, it was suggested that REM and REST, which define the effective detection zone, are capable of equivalent density estimation.

We conducted a literature survey of the least-known Pteromys flying squirrel, the Jehol flying squirrel Sciuropterus (= Pteromys) wulungshanensis Mori, 1939, whose type specimen was collected on Mount Wu-ling in northeastern China during the First Scientific Expedition to Manchoukuo (June-October, 1933). We identified and examined seven publications related to this species, which were published before 1945, including the original English paper describing Sciuropterus wulungshanensis by Tamezo Mori. Kyukichi Kishida, one of Tamezo Mori’s colleagues on the expedition, identified the flying squirrel as a new species and assigned a new scientific name, “Sciuropterus mureisanus”, before January 1936, when Mori started writing his paper describing Sciuropterus wulungshanensis. We concluded that “S. mureisanus” is a nomen nudum for the flying squirrel. The type specimen is stored at the National Museum of Nature and Science, Tokyo (Japan), but the circumstances of its acquisition remain unknown.

Small Indian mongoose Urva auropunctata, an invasive alien species on Amami-Oshima Island, has been exterminated through control programs of the Ministry of the Environment, Japan. In the present study, we established an environmental DNA (eDNA)-based method for detecting U. auropunctata as a component of the biosecurity system, which aims to prevent the entry and/or spread of harmful organisms, to address its re-invasion into Amami-Oshima Island. We developed a primer/probe set that is specific to U. auropunctata by comparing mitochondrial DNA sequences of terrestrial mammals inhabiting Amami-Oshima Island and/or Okinawa Island. With this set, we detected eDNA of U. auropunctata from the drinking water pots used by U. auropunctata in captive facilities inhabiting Amami-Oshima Island and Okinawa Island. This suggests that our eDNA-based method could be an effective tool within the biosecurity system for detecting U. auropunctata. Future studies should aim to validate the effectiveness of our eDNA-based method in field conditions.

Ryukyu long-furred rats (Diplothrix legata), which are endemic to Amami-Oshima, Tokunoshima, and Okinawajima Islands, are omnivorous. During the early morning hours of May 18, 2024, an adult feeding on the fruit of the fragrant screw-pine (Pandanus odorifer) which does not grow in the rat’s primary habitat in montane forests, was observed on a road surrounded by a coastal forest in the northern part of Okinawajima Island. Later that night, a roadkill carcass of an adult was found in the same location. Although this carcass might not be the previously observed individual feeding on fragrant screw-pine, the stomach contents of the carcass were analyzed using DNA metabarcoding. This analysis revealed, for the first time, the consumption of the fragrant screw-pine and land hermit crabs (Coenobita cavipes) by this species.

In the 2001 fiscal year, feral individuals of Pallas’s squirrel (Callosciurus erythraeus), an invasive alien species, were found and caught at the northern foot of Mount Kirishima. In the 2013 fiscal year, a field study conducted by the Ministry of the Environment revealed that one in ten stands contained several damaged Camellia japonica trees with old scars caused by the bark-stripping behavior of the alien squirrels. From December 2024 to January 2025, I conducted a field study in the same area and found that five new stands among 19 stands contained damaged Camellia japonica, Machilus thunbergii, and Cinnamomum yabunikkei trees with old bark-stripping scars, though no fresh bark-stripping scars were identified. Considering the unclear status of this population, the local government must monitor the population. In addition, I discuss a potential methodology for such monitoring.

A preliminary field study was conducted in April 2025 near an amusement park in western Saga Prefecture, Kyushu Island, where invasive alien Pallas’s squirrels Callosciurus erythraeus were legally being kept and exhibited under license from the Ministry of Environment, Japan. I found that one out of three stands contained twelve damaged Camellia japonica trees with old bark-stripping scars, implying that Pallas’s squirrels were feral in this area. The current distribution and density of the alien squirrels is unknown, as well as the pathway. Further surveys of this feral population by local authorities are needed to understand the current situation and to take effective countermeasures.

Three cases of wild Orii’s shrew (Crocidura orii) were observed on Tokunoshima Island from April 2020 to April 2024. The observational records of wild individuals of this species, for which no field habitat records have been obtained since 2009, are extremely valuable and can serve as a basis for the construction of future conservation measures for this species in the future. In analysis of three wild individual observations revealed that, Orii’s shrews were documented to be active during the day and night and to produced calls. The presence of deciduous leaves was considered important in suggested to be important for their habitat. Together with considering the previous 21 records, this species is suggested to be active from fall to spring, and is found live in a various of environments, ranging from plains to mountains, not only in limited to highly naturalistic forests.

The sika deer Cervus nippon is widely distributed in the Japanese archipelago, and studies on food habits are finding the geographical variations: the main foods in the cool-temperate zone in the norther areas are graminoids (grasses and sedges), while those in the warm-temperate zone in the southern areas are evergreen broad-leaves and fruits. However, information for the mainland Kyushu has been insufficient. Although two studies recently analyzed the dietary compositions in Kyushu, the vegetation was impoverished due to heavy browsing by deer at high-density, and the dietary compositions seemed to be different from the natural ones. Therefore, we conducted analyses of the fecal compositions of the sika deer at low-density in an evergreen broad-leaved forest in the Takakuma Mountains, Kagoshima Prefecture, southern Kyushu. The results showed that evergreen broad-leaves occupied about 60% in winter, making an important contribution to the information on north-south variation in the food habits of the sika deer.

We confirmed the carcass and night roost of Rhinolophus cornutus on Kozu-shima Island, Izu Islands, Japan. A carcass was found in a warehouse in August 2024, and the night roost was confirmed in a public restroom in June and September 2024. These are the first records of bats on Kozu-shima Island. Bats were confirmed on six of the nine inhabited islands of the Izu Islands.

To support effective goal setting and the development of evidence-based strategies for sika deer management, we proposed a method for establishing management goals at a pivotal moment. This approach involved organizing the content of deer management plans from 45 prefectural governments and evaluating the characteristics of indicators through case studies. While many prefectures set management goals for deer density in their plans, only a few address goals related to agricultural damage and ecosystem impact. In the case study analyzing the relationship between damage and deer density using data from Fukui, Mie, and Tokushima Prefectures, the relationships varied across the regions. Plans for setting implementation goals varied by prefectures.

Based on these findings, we propose the following: 1) Set numerical management goals for reducing agricultural damage and protecting ecosystems based on the relationships among monitoring indices; 2) Establish target values for deer density using locally collected monitoring data, rather than adopting values from other areas; 3) Set management goals in the specified wildlife management plans, and set the implementation objectives in the annual plan; and 4) Ensure that the national and local governments set consistent management goals while promoting the establishment of a system for technical support and information management.

The amount of damage to crops caused by sika deer (Cervus nippon) is a factor in the increase in abandoned farmland resulting from a declining willingness on the part of rural residents in Japan to engage in farming. To improve the situation, it is important to install and manage appropriate protective fences, to capture nuisance wildlife, and to establish a damage-prevention system in which residents take the initiative to protect and capture wildlife. However, as the population declines, it is becoming more difficult to establish such a system. In this study, we targeted two villages where agricultural damage caused by deer is serious due to the entry of deer through openings in community fences, even though these fences are maintained and managed. We demonstrated that agricultural damage caused by deer can be reduced by capturing the offending individuals, activities which are led by local residents and local government organizations in the school district. During the 5-year study period, more than 10 deer per year were captured at the opening of the community fence, damage was reduced to almost zero in both villages, and the results of a spot light count showed a declining trend in the presence of deer within the 300 m buffer. The results of interviews with residents also showed an increase in the number of comments on the reduction in agricultural damage, as well as the realization that the number of deer sightings has decreased.

It was also shown that it is effective to establish a system that enables the selection of capture sites and the treatment of captured animals in accordance with local conditions, as well as to coordinate activities that are impossible in a single village with organizations that span multiple villages, such as school districts.

Kanagawa Prefecture established a deer management plan in 2003 in response to the decline of beech forest floor vegetation since the 1980s. One of the goals of the plan is to conserve biodiversity, and the prefecture is managing deer populations since fiscal 2003. Prior to population management, deer-exclosure fences have been installed in beech forests since 1997. In some sites of the areas, deer density has decreased and vegetation cover has increased as a result of population control. However, the increase was due to grazing-tolerant species of deer, and the increase in vegetation cover was limited to a few sites. Twenty years of population management, fencing, and monitoring have shown that it is extremely difficult to restore declining vegetation to its pre-deer impact state through population management. In order to overcome the current situation where vegetation does not recover as expected even when deer density decreases, I proposed the following three points: (1) to understand the deer density index during the vegetative growth period, (2) to shift the timing of population management to the vegetative growth period, (3) to set vegetation recovery goals considering vegetation types and to select or combine management methods corresponding to these goals.

The Specified Wildlife Management Plans for sika deer (Cervus nippon) populations in 45 prefectures from 2020 to 2023 were reviewed to assess the current status of, and issues related to, monitoring and evaluation. Hunting records and camera trap surveys were used to monitor deer distribution. Catch and sighting per unit effort during hunting have been widely adopted as relative density indices; however, because the proportion of culling has increased, information must be collected on both indices for culling activities. Several methods for estimating deer density or abundance have been adopted according to local conditions. Recently, many plans have implemented hierarchical Bayesian models to estimate deer density, highlighting the need to improve the accuracy of each density index and to continue surveying multiple indices. Regarding the damage to agriculture and forestry, many plans use damage statistics as indicators, but collecting objective indicators on a small scale is also essential. Vegetation monitoring efforts vary widely among regions, indicating the need for early action informed by the efforts of preceding regions. Annual evaluation of principal measures by a scientific evaluation organization, followed by revision of management plans based on the results, is important.