“Yambaru National Park” was born in 2016, and “Amami Gunto National Park,” in the area called “Central Ryukyus” in the Ryukyu Chain, was born in 2017. The significance of the designation of these national parks is now high in the hopes of protection and security for “Amami-Oshima, Tokunoshima Island, The Northern Part of Okinawa Island and Iriomote Island of the World Natural Heritage Nominated Site”. The biota of the Central Ryukyus is unique, isolated from the Eurasian Continent in the late Miocene to early Pleaistocene (approx. 11.63Ma to 2Ma), passing through a period of long isolation, and now showing unique evolution and high endemism in an island environment lacking predatory mammals. One rabbit species and rodents of the relict endemic species are representative. In recent years, there has been much research, and new results were added also in this special reports in the Mammalian Science. In response to endangered species and conservation of biodiversity in the Ryukyu Chain, the Mammal Society of Japan has been submitting requests and opinions for over 20 years. For new protection measures and designation of the World Natural Heritage in this region, it is important to conserve the habitat of endangered species, and to strengthen countermeasures against alien mammals as future tasks.

In the northern part of Okinawa Island, we carried out a food habit study of the Ryukyu long-furred rat Diplothrix legata, with direct observation and trace surveys. Food items utilized by the rat consisted of 31 plant species and 10 animal species. Various plant parts were utilized: seeds of 22 spp., fruits of 8 spp., leaves of 3 spp. and bark of 2 spp. Thus, the Ryukyu long-furred rat prefers seeds and fruits, though it showed a wide range of food habits. The rat changed food items utilized along a gradient of plant phenology. According to previous studies, the rat breeds from summer (late July) to winter (February), and these seasons seem to correspond to the major fruiting periods in forest habitats. We conclude that the most suitable habitat of the rat, in terms of food availability, is forest consisting of various plant species which fruit throughout the year.

A part of Prefectural Route 2 and 70 on northern Okinawa Island, Japan, crosses forested areas containing several endangered species. The prevention of roadkill of endangered species has become an important issue in island species conservation. We conducted a census of the Ryukyu long-furred rat (Diplothrix legata), a species endemic to the Nansei Islands, counting live individuals and roadkill nearly every day for 6 years between May 2011 and April 2017. A total of 122 records (75 live individuals and 47 roadkill) were obtained along the road in the census. Based on these records, we created a roadkill risk map for this species along Route 2, and compared the risk map to priority areas for the prevention of roadkill set along Route 2. We also evaluated the effectiveness of the priority area using roadkill rate per individuals. We found that only part of the high-risk area had been targeted, leaving some high-risk areas without protection. Road kill rate did not decrease at the priority area. Our study may contribute to improving actions for the prevention of roadkill by illustrating the actual risk distribution and evaluating effectiveness of current actions.

Since there is limited information on the habitat distribution of Diplothrix legata in Tokunoshima Island, we took a brief census along forest roads by using bite marks and feces as indicators of the status of D. legata in August, 2015. Bite marks and feces were found in areas around Mt. Amagi, Mt. Sasontsuji, Mt. Inokawa, Mt. Minada, Mt. Hage and Mt. Inutabu. Moreover, we found some marks and feces in the southern area of Mt. Inokawa and the western area of Mt. Inutab, where there have been no records until the present study. Hence, this method is useful for brief distribution surveys and monitoring procedures for D. legata.

The Ryukyu long-furred rat is an endemic species to Japan, and recognized on the IUCN Red List as “Endangered”. Little is known of its biology. We fortuitously obtained a male Ryukyu long-furred rat suspected to have been killed via a traffic accident on Tokunoshima Island, Kagoshima, Japan in August, 2016, and observed its genitals via light microscopy and scanning electron microscopy to obtain reproductive information on this species. Morphologically matured sperm were found in the epididymis, although they were very few. Spermatogenesis was observed in the seminiferous tubule of its testes. Therefore, the Ryukyu long-furred rat we observed would have had a morphologically matured testis and epididymis, and would have become reproductively functional in this season. Hereafter, we need to gather more information to know the ecological and reproductive traits of the Ryukyu long-furred rat.

We reported long-term feeding cases of rescued Ryukyu long-furred rat (13 individuals) and Okinawa spiny rat (1 individual) kept in our animal clinic. Several kinds of artificial food were used as principal food, and a variety of plant materials (fruits, seeds, vegetables, etc.) and animal materials (small animals, bird eggs, etc.) were used as side menu items. The maximum longevity under captive conditions was 3.9 years in the Ryukyu long-furred rat and 4.1 years in the Okinawa spiny rat. We also reported some behavior observed in captive conditions, biochemical examinations of blood, and causes of death. These findings are expected to contribute to ex-situ conservation of the two species in the future, as well as of rescues of injured individuals.

We studied historical distribution trends of the critically endangered Okinawa spiny rat (Tokudaia muenninki; Rodentia, Muridae), which has recently become restricted to the northern part of Okinawa Island. Various kinds of literatures, specimens, fossil records, and observation records were compiled and evaluated. We suggest that 1) Okinawa spiny rat was distributed throughout Okinawa Island and Ie Island in the prehistoric period, and 2) it was restricted to the northern part of Okinawa Island (from northern Nago City to Kunigami Village) when discovered in 1939. Proportions of alien carnivore’s feces containing Okinawa spiny rat (spinous hairs, bones, etc.) were high (75–80%) in the late 1970s, decreased greatly by late 1990s, and became 0% in the January 2016 survey. This study also suggests that the estimated habitat area of the species decreased 99.6% from the prehistoric period and 98.4% from the year of species discovery in 1939.

A camera trapping survey in the northern part of Okinawa Island suggests that the Okinawa spiny rat Tokudaia muenninki (Rodentia, Muridae) changes its daily activity cycle throughout the year, being diurnal in summer and nocturnal in winter. In the summer study period (late June to late September), the Okinawa spiny rat was photographed only in daytime (n = 12, 10-day average of daily mean air temperature = 23.5–26.9°C), while in the winter study period (early January to late March) the rat was photographed only at night (n = 13, 10-day average of daily mean air temperature = 13.8–17.5°C). On the other hand, the sympatric invasive black rat Rattus rattus was photographed at night in both seasons (n = 15 in summer and n = 6 in winter), suggesting that the activity patterns of the two rat species overlapped only in winter. Little is known about the biology of the Okinawa spiny rat, and our study is the first report of such unique behavior of its daily activity changes. More studies are needed to understand the significance of the behavior and to reveal its influence on the recent population decline of the species.

Predation by feral cats (Felis catus) is a serious problem for native insular species in the world, including Japan. In this article, we present a case study of feral cat predation on a weaning juvenile of the Amami rabbit (Pentalagus furnessi) on Amami-Oshima Island. The Amami rabbit is an endemic species in Amami-Oshima and Tokunosima Islands of Japan. From January to March 2017, we surveyed the maternal behavior of the rabbits with a camera trap. The juvenile was born on the night between January 14 and 15, and it was hunted by a feral cat at 1:00 on February 19 (35 days old). In the night before hunting, the mother did not seal the entrance of the nursing burrow with soil for the first time. Because the juvenile disappeared from videos after hunting, it might have been eaten by a feral cat, or died from injuries sustained while being hunted. The feral cat revisited the nursing burrow for 30 minutes, the following day, and 4 days after hunting. The mother also revisited for the following day after hunting. Predation pressure on young rabbits might affect their population dynamics. To protect the population of Amami rabbit on Amami-Ohshima Island, feral cats need to be removed from the forest as soon as possible.

We studied the spatial and temporal distributions of carcass records of the Amami rabbit, Pentalagus furnessi, on Amami-Ohshima Island, Japan, based on a ten-year official survey data from April 2007 to March 2017 (n = 499). Road-kill accounted for 22.6% of the records, including 110 carcasses and 3 seriously injured animals immediately after traffic accidents. A large proportion of cases (82.3%, n = 93) occurred in the central and southern parts of the island, especially at Aminoko Pass, Santaro Pass, Prefectural Route 612, and Prefectural Route 85. The frequency of road-kills showed a seasonal change; low in summer and high in autumn and winter.

Studies on animal reproduction and maternal care behavior provide useful information on female parental investment into the development and growth of the young, and are important especially for the conservation of endangered animals. Amami rabbit (Pentalagus furnessi, Leporidae, Lagomorpha) mothers dig and use special breeding nests away from their own burrows. We recorded two cases of reproduction and maternal care behavior using a camera trap from April to May 2016 and from December 2016 to February 2017. Maternal care behavior consisted of digging soil, making a breeding nest tunnel, parturition, and lactation. Each mother visited the breeding nest at midnight, and 0200 to 0300 hours to nurse and suckle one to two newborns. Suckling occurred once every two days during the nursing period. Suckling of newborns outside of the breeding nest began when the newborns were ca. 10 days old. Newborns began to spend time outside of the nest after ca. 30days old. As the newborns grow, mothers decreased the time spent at the breeding nests, and time spent suckling. They also decreased the time spent opening and closing the soil cover of the entrance. Therefore, mothers reduce parental investment as the young grow, which was initially low immediately after giving birth.

I reviewed and analyzed available information in the literature and fossil/semifossil records relevant to the geographic distribution of the Ryukyu flying foxes, Pteropus dasymallus, in the Ryukyu Archipelago, and estimated temporal changes in the range of this species. The Ryukyu Archipelago represents the northernmost extremity of the genus Pteropus, which has obviously been diversified in the tropics. The margins of this distribution is surmised to be a harsh environment, often making populations unstable. Especially in such volant animals as bats, between-island migration may occur relatively easily. Our results suggest: 1) the distributional range of the Ryukyu flying fox has temporally changed at a large scale due to natural dispersal and local extinction; 2) the abundance and range of P. d. inopinatus on the Okinawa islands are respectively currently increasing and expanding; and 3) populations of P. dasymallus on several islands, such as P. d. dasymallus on Kuchinoerabujima Island, are likely to have originated via artificial transportation from the Yaeyama islands. These results suggest that temporal changes in the distribution of the Ryukyu flying fox may have occurred during a relatively short period under the strong influence of human activities. In future studies of insular animals, we should consider both natural spatial dynamics in progress and the influence of human activities.

In order to elucidate the effects of thinning on Apodemus speciosus and A. argenteus populations in Japanese cedar Cryptomeria japonica plantations, we conducted population surveys in two sites composed of a plantation and an evergreen broad-leaved forest in southern Kyushu, Japan. In one site, about 50% of the volume of cedar trees in the plantation were cut in September 2012. All mice inhabiting the plantation disappeared just after thinning. New individuals of A. speciosus and A. argenteus began to be captured in the plantation three and six months after thinning, respectively, and both mice species recovered in the third year after thinning, when the ground vegetation had recovered. Meanwhile, in the non-thinning site, the number of trapped mice did not largely change throughout the year in 2012. These results show that thinning should produce pronounced impacts on mice populations through drastic disturbances of habitat condition, and the effects are larger and longer for A. argenteus than for A. speciosus. However, we also suggest that mice populations can recover within three years after thinning.

We have performed studies to estimate the brown bear (Ursus arctos) population using a hair snagging method on the Oshima Peninsula in Hokkaido, Japan. In the present study, we investigeted the influence of locational conditions of hair traps on success rate of hair capture. We employed a zero-inflated model to analyse the influence of locational condition of hair trap sites on both bear presence around trap sites, and bear preference to the trap sites. The results show that the locational conditions of hair traps did not have any influence on the presence of bears, but have affected the detectability of bears by the difference of the cover rate of Sasa bamboo (Sasa spp.). When the proportion of Sasa bamboo was sparse or intermediate, brown bear hair could be captured more frequently by hair traps than when it was dense.

We conducted an experimental study on the relationship between transportation behavior and food size (or weight) for Japanese squirrel (Sciurus lis) in a suburban forest of Nagoya city, Japan. We placed artificial food samples of two or three sizes on a feeding tray, randomly selected from eight different sizes of 1–15 g. Larger food was more likely to be transported from the food source and into tree canopies than smaller food. This could be because larger food caused a higher risk of predation (resulting from longer handling time) and of cache-robbery by mice and other squirrels (because of higher energy contents). Compared with small food, large food was also dispersed farther away to reduce density-dependent cache robbery. However, the heights transported by squirrels did not differ with food size, indicating that height was not important in avoiding predation during feeding or cache robbery when food was hoarded.

Studies of the food habits of mammals often adopt fecal analyses. The diversity of fecal composition is usually calculated for sample groups representing a place or a season. The diversity is, however, obtained also for each sample. The former and the latter are here termed as “population diversity” and “sample diversity”, respectively. Both metrics have importance but only the former has been used. In this study, both diversity metrics were calculated for five animals from six locations: the sika deer (Cervus nippon) from two locations, the Japanese serow (Capricornis crispus) and the wild boar (Sus scrofa) from one location, the raccoon dog (Nyctereutes procyonoides) at two locations, and the Japanese marten (Martes melampus) at two locations. Population diversity and sample diversity were close in deer, serows, and boars, while population diversity was greater than sample diversity in raccoon dogs and martens. Among the latter two animals, the differences were greater in the marten than in the raccoon dog. These differences were discussed in terms of body size, food habits, digestive physiology, and food availability.

The ceiling inside a tunnel, in southeastern Oita Prefecture, was utilized as the roost of Murina hilgendorfi and Myotis bombinus in the active period. As the result of our investigations from May until July, Mu. hilgendorfi formed a temporary dense colony in June. We captured the colony, consisting of 13 pregnant females in June 2016 and 2017. Females in the later stages of pregnancy moved into the tunnel and clustered tightly. Such dense colonies maintain high body temperatures, and may hasten the growth of their fetuses. After that, they leave the tunnel, and give birth to young and form nursery colonies elsewhere.

The Japanese river otter (Lutra lutra nippon) is an extinct species. In 1979, the last witnessed sighting of this species was recorded in the Shinjo River, Susaki, Kochi Prefecture. Little is known about the behavior of the last individual found in 1979, because of the scarcity of spatiotemporal information on its existence around the river. We identified the date and location of the information and rearranged the information spatiotemporally. Analysis of the information revealed that the last individual found in 1979 showed two discriminating characteristics in terms of its appearance and behavior. The individual had a remarkable scar on its neck at one time and no scar at other times. In addition, the individual was habituated to humans at one time, and did not display such behavior at other times. There were reliable reports that a female individual inhabited the Shinjo River in 1974, and a male one inhabited the river in 1975. The lifespan of the Japanese river otter is presumed to be ten to fifteen years. These results imply that more than one individual could possibly have inhabited the Shinjo River in 1979.

Fifteen papers on the food habits of the Japanese marten (Martes melampus) were reviewed in order to assess which types of fruits martens prefer. A total of 97 species and 11 genera were listed. Among the 97 species, as many as 89 species were fleshy fruits. The fruit of Hovenia dulcis is morphologically a drupe, but the pedicle swells and tastes and smells sweet and thus functions as a “fleshy fruit”. The other 8 species were dry fruits. Among them, the fruits of Euonymus hamiltonianus and Celastrus orbiculatus contain “fleshy” seeds. Two capsules of Anacardiaceae contain high lipids. Fruits of 76 species (78.4%) are colorful and 70 species (72.2%) are small (< 10 mm in diameter), suggesting that these typical bird-dispersed fruits are also preferred by the marten. Large and dull-colored fruits included 3 species, and Actinidia arguta and H. dulcis showed high frequencies. The growth forms and the habitats seemed to be biased to lianas and forest-edge plants, respectively. This review showed that the marten fed on many small and colorful bird-dispersed fruits, as well as large and dull-colored fruits such as A. arguta and H. dulcis.

During the course of field investigations using nest boxes and camera traps, the Japanese giant flying squirrel Petaurista leucogenys (Rodentia, Sciuridae) was recorded on 14 August 2015 from Mount Hachiman-dake, Saga, northwestern Kyushu, Japan. This is the first information on the habitat of P. leucogenys from Saga Prefecture and the first record of its confirmation in northwestern Kyushu, including Saga and Nagasaki Prefectures, in 47 years. In camera trap records, an individual of the North American raccoon Procyon lotor (Carnivora, Procyonidae) was also recorded climbing a tree. Although further investigations were conducted also from April to October 2016, P. leucogenys was not recorded in that year. In contrast, P. lotor was frequently confirmed to visit nest boxes, yielding concern of its negative effects on native animals.

In 2011, we reported the population density of sika deer (Cervus nippon) in Fudakake of the Tanzawa mountains from 1998 to 2007. We continued investigating the population density of sika deer by the block-count method until 2015. Sika deer were captured for population management from 2007 to 2015 in the study area. We confirmed that the density of deer in the management period was lower than that in the non-management period. This result suggests that the number of deer decreased through capture in the study area.

Human infections with poorly known acanthocephalans (Corynosoma spp.), that use pinniped mammals as final hosts, have been found from Hokkaido, and reported in gastroenterological and parasitological journals one after another. In both reports, this parasite zoonosis represented common characters found from small intestines with a relatively long latent period. Further investigations, including understanding the background of increased infection and monitoring of future trends, are needed to establish appropriate measures and prevention.

The invasive alien species, the Eurasian red squirrel (Sciurus vulgaris), was reported to establish in the Sayama Hills, Kanto Plains, in 2000. The Mammalian Society of Japan submitted the request form in November 2013 to the Ministry of Environment to start countermeasures immediately. In April 2014, the Ministry of the Environment started a survey to clarify the distribution of alien squirrels in the Sayama Hills, and at the same time, started to capture the squirrels. We found squirrels at 17 points by sighting, food remains, and monitoring cameras. A trapping survey at 17 points also captured 32 individuals of S. vulgaris and one individual of S. lis over three years. After that, sighting information ceased, and monitoring camera did not detect the squirrel anymore. We suggest that the early countermeasures were successful, but we need further investigations to know whether alien squirrels remain in Sayama Hills, or if they dispersed to the surrounding forests.