In this review, I discuss the relationship between the Japanese wolf and other gray wolves (including dogs), as revealed by whole genome analyses. The Japanese wolf is a lineage of the Asian gray wolves that inhabited the southern part of the Japanese archipelago (Honshu, Shikoku, and Kyushu) until their extinction approximately 100 years ago. The divergence of the Japanese wolf lineage from other gray wolves in East Asia is estimated to have occurred approximately 17,000 to 40,000 years ago. The Japanese wolf is the closest to a dog lineage among the gray wolves and is estimated to have introgressed with the ancestor of the East Eurasian dogs. Owing to this introgression, the extant East Eurasian dog genomes include a part of the genome from the Japanese wolf ancestry. The presence of a hybrid individual between a dog and a Japanese wolf in the Edo period indicates that dogs and Japanese wolves may have had a close relationship in the southern part of the Japanese archipelago.

The Japanese wolf (Canis lupus hodophilax) became extinct leaving many unanswered questions. Morphological research and discussions about the identification of the Japanese wolf have been carried out for many years, but the phylogenetic position of the Japanese wolf has not been determined in almost 180 years since Temminck established its scientific name as Canis hodophilax. Genetic analyses of the Japanese wolf have steadily progressed since 2009, leading to the conclusion that the Japanese wolf is a subspecies of the gray wolf (C. lupus). Although morphological studies have not been able to reveal the phylogenetic position of the Japanese wolf, detailed osteological research has revealed many morphological features, especially in the cranial shape. It has been reported that the Japanese wolf has many characteristics different from other gray wolf subspecies and dogs, for example, a bisected rostral alar foramen and palatine bone with an anterior notch. However, it also has characteristics of both other wolf subspecies (undeveloped stop) and dogs (small flat tympanic bulla). Recently, three-dimensional analysis and reconstructions of the Japanese wolf have been made using digital morphological information. Morphological studies of the Japanese wolf will continue to be important for functional understanding.

We conducted a tracking survey of five masked palm civets (Paguma larvata) using GPS collars in two urban areas of Morioka City, Iwate Prefecture, Japan. In this study, we elucidated the ecology of the civet in urban areas, focusing on the home range and movement-inhibiting factors. The civets were mostly nocturnal and rested in their dens during the daytime. The home range size of civets ranged from 63.6 to 298.4 ha (100% MCP), which was similar to that of previous studies conducted in rural areas. The home range of each individual overlapped widely. Roads, rivers, and railroad lines functioned as barriers to the movement of civets; however, roads only acted as barriers if they were wide, had a high-speed limit, and had well-lit surfaces. Monte Carlo simulations focusing on the use district of urban planning where GPS data were recorded showed that the civets avoided commercial districts. Although the reason behind civets avoiding commercial districts is unclear, the results suggest that the use district zoning may be used as an indicator of the environmental differences that affect civets’ behavior.

Several studies have proposed that woodland areas are used as resting and breeding sites, and the adjacent agricultural sites are used as feeding sites by raccoon dogs (Nyctereutes procyonoides) in suburban environments. However, the sites examined in these studies did not employ animal tracking but relied on questionnaire surveys by local residents. Therefore, this study examined the nocturnal and diurnal habitat selection by eight raccoon dogs throughout different seasons in suburban areas with agricultural sites by radio telemetry. The result showed that during nighttime, raccoon dogs preferred agricultural sites throughout all seasons, and woodlands, bamboos and bamboo grasslands in some seasons. The findings suggested that agricultural sites in suburban areas are an important feeding sites for raccoon dogs. Additionally, the camera trap set at the daytime rest site confirmed the presence of an adult male that may be a helper.

Non-indigenous Callosciurus squirrels have been introduced into Hamamatsu City of Shizuoka Prefecture, Japan in the 1980s, and since then, their distribution has been expanding from urban to suburban areas. Population genetic analyses based on the mitochondrial D-loop gene have revealed contamination of Finlayson’s squirrels Callosciurus finlaysonii in addition to the presence of Pallas’s squirrels Callosciurus erythraeus, but the past studies are confined to urban areas only. We thus re-examined the genotypic composition of 266 specimens widely exterminated from the city between June 2019 and January 2021. The analysis revealed that two haplotypes derived from Finlayson’s squirrels were dominant. No individuals with mitochondrial genes derived from Pallas’s squirrels was found, although the body color pattern of them matched with this squirrel species. The haplotype distribution in Hamamatsu City was independent of artificial structures such as highways and vegetation, suggesting that individual dispersal occurred widely.

Collecting of subterranean moles was conducted on Dogo, Oki Islands, in November 2021. As a result, two lesser Japanese moles (Mogera imaizumii), along with five large Japanese moles (Mogera wogura) were captured. This is the first record of M. imaizumii to be found on Oki Islands, thereby indicating a newly discovered relic of M. imaizumii in western Japan.

Raccoon dog Nyctereutes procyonoides is euryphagous animal, and could change their food-habits flexibly according to their surrounding environment. However, there were few studies which tested the flexibly focusing landscape gradients. In this study we tested the relationship between food habits of the raccoon dogs and surrounding landscape of their habitat using fecal analysis method in 7 urban parks at west region of Tokyo, Japan. We collected the droppings from each park for one year from September 2020 to October 2021 and analyzed them based on the land use of each park. Our results showed that there was positive correlation between urbanization of around the park and use of artificial resources by the raccoon dogs, and that the animals in heavily urbanized parks tended to use artificial resources through 4 seasons. These results suggested that the raccoon dogs could change their food habits according to their surrounding landscape of habitat regarding to urbanization.

It has been reported that the activity patterns of wild boars are affected by temperature and human activities. However, there is no literature on the activity patterns of wild boars in North Tohoku, where their population is expanding. To estimate the diel activity patterns of wild boars, we conducted camera trap surveys in Shizukuishi, Iwate Prefecture, Japan. The wild boars tended to be nocturnal from spring to autumn. More than 50% of the captured events were recorded before and after sunset. In winter, the number of captured events that occurred during the day was significantly higher than expected. This indicates that the wild boars may have switched to a diurnal cycle. Our study implies that wild boars alter their diel activity patterns to adapt to the low temperatures and snowfall that are characteristic of the winter in North Tohoku.

Japanese serows (Capricornis crispus) of both sexes maintain intrasexually exclusive territories, defending most of the home range by territorial behavior characterized by severe chase, and fundamentally monogamous pairs can be recognized by patterns of intersexual range overlap. For further comparisons of regional differences in the territoriality of the Japanese serow, we investigated seasonality in the observed frequency of such chasing behavior, which has not been reported previously, by direct observation of serows identified individually in a 100-ha study area on the Shimokita Peninsula, northern Japan, on 1,263 days between March 1976 and October 2015. We observed 25 incidents (20 between males and 5 between females) of chasing behavior in every month except for April. The annual frequency of chasing behavior was significantly higher between males (1.6 cases/100 days) than between females (0.4 cases/100 days). Severe chases involving territorial adults showed a seasonality in frequency, being higher in the autumn rutting season, whereas no seasonality in the frequency was found between territorial adults and non-territorial adults or juveniles.

We recorded a Eurasian red squirrel Sciurus vulgaris hoarding a Japanese walnut Juglans mandshurica on the ground and retrieving it, using an infrared-triggered camera installed in Hokkaido University, Japan. The Eurasian red squirrel hoarded a walnut on December 16th, 2021, in non-snowy conditions, and that retrieved it from 21 cm under snow on January 8th, 2022 (23 days after hoarding). In this case study, the squirrel did not use olfactory or visual memory, suggesting that the Eurasian red squirrels emphasize spatial memory to find stored food. The fact that the squirrel reached the walnut hoarding site without confusion, even though it did not reconfirm the site during the 23 days, suggests that a Eurasian red squirrels have a very accurate memory.

An introduced population of sika deer Cervus nippon has become established on Kikai-jima Island, Japan. It originated from 15 individuals introduced around 2002. To clarify the origin of the deer, we sequenced mitochondrial DNA using fecal and muscle samples collected on Kikai-jima Island. Nineteen haplotypes, including those from previous data, were determined with 998 bp sequences of the control region of mitochondrial DNA. The haplotype from Kikai-jima Island was identical to Hap1, which was unique to Mage-shima Island, suggesting that the introduced deer established on Kikai-jima Island likely originated from Mage-shima Island. The introduction of the sika deer to Kikai-jima Island indicates that the transfer and escape of captive deer have been repeated even in recent years. Regulations on the translocation, sale, or escape of captive deer need to be implemented. In addition, there are concerns about the impact of the introduced deer on the natural vegetation of the Kikai-jima island. It is desired that a system will be established as soon as possible to implement sufficient trapping efforts.