Mammal Study

Bovid morphologies differ depending on body size and habitat. We hypothesized that bovids also vary their mobility of fingers and toes depending on body size and habitat. In this study, we compared the shape of the distal ends of the metapodial bones and the proximal facet of the proximal phalanges to examine the metapodiophalangeal joint gaps and simulated the three-dimensional motion of the bovid metapodiophalangeal joints during the opening and closing states through CT scans to investigate whether the mobility of the finger and toe is affected by body size and habitat. The results showed that species with gaps in the metapodiophalangeal joints had higher mobility and that species living in mountains had larger gaps. This suggests that bovids living in unstable terrains can move better on unstable substrates due to their increased mobility of digit. Similarly, our results indicate that smaller bovids are more likely to display variations in the mobility of digits than larger-sized bovids since greater body size reduces the range of mobility to avoid dislocation risk. Our results show that bovids have been able to be flexible to a range of body sizes and habitats by varying the size of their metapodiophalangeal joint gaps.

Sociosexual behavior is not directly related to reproduction. It is observed between mature and immature individuals of both sexes and interactions can be between mixed- or same-sex individuals. This behavior may have important social functions. We observed and recorded the sociosexual behavior of wild Indo-Pacific bottlenose dolphins (Tursiops aduncus), underwater off Mikura Island, Japan, with regards to erection and mounting. This behavior was observed mainly between mothers and sons and in groups of subadult males (age 1–13 years). In subadult males, mounting behavior toward one passive individual from two or more individuals playing an active role, occurred in most cases. This behavior involving three or more participants has rarely been observed in other animal species, except for bowhead whales (Balaena mysticetus), common bottlenose dolphins (T. truncatus), and beluga whales (Delphinapterus leucas). Sociosexual behavior in the Mikura Island dolphins may not be agonistic because individuals in the passive role did not try to escape from the individuals playing the active role. Further studies on sociosexual behavior T. aduncus could reveal the social functions of this behavior, such as younger animals practicing mating behaviors required as adults and developing their relationships for when they are adults.

In Jangsudae of Seoraksan National Park, South Korea, 14 mammal species have been listed, including ten medium- and large-sized species; additionally, this region is an important habitat for the endangered long-tailed goral (Naemorhedus caudatus). In this study, a camera trap survey was conducted over 103 monitoring days at 18 sites in Jangsudae to evaluate the minimum trapping effort (MTE) needed to detect the ten listed mammal species. The most photographed species were the long-tailed goral, wild boar (Sus scrofa), and Asian badger (Meles leucurus), accounting for 77.1% (n = 366) of the total independent photographs. Long-tailed goral, the most frequently captured mammal species (44.8%), was captured at 17 camera sites (relative abundance index = 206.8). According to the rarefaction analysis, 1840 camera days (102.2 monitoring days at 18 camera sites) were required to photograph all ten resident species. Moreover, at least 1010 and 664 camera days were required to detect 95% and 90% of the ten residential species, respectively. MTE was evaluated in summer when wild species were highly detectable owing to their high activity. Future studies should evaluate MTE through one-year long-term monitoring that includes all four seasons, and compare the results with those of this study.

The purpose of this study was to examine the influences of seasonal and annual changes in weather conditions, natural food abundance (pine seeds), and the spacing of feeders on the use of walnuts on feeding tables by Japanese squirrels (Sciurus lis) in a suburban forest in Nagoya City, in summer (Jul–Aug) and autumn (Sep–Oct) from 2019 to 2021. Feeder-use increased in severe weather conditions, i.e., low temperature and heavy rain in both seasons, and decreased in summer of the year when pine-seeds were abundant. Feeders were used more in autumn for hoarding before the winter. The intervals among eight feeding tables were widened during the study from c. 100 m in 2019–2020 to c. 300 m in 2021. In the years when the feeders were placed at short intervals, we found two behavioral modifications due to the supplemental feeding: a concentrated distribution of many individuals in 2019 and exclusive occupation by a particular female in 2020. In contrast, in 2021 with the feeding tables placed at wider intervals, the distribution of individuals expanded over the entire study area, and the use of supplementary feeding decreased, while seed consumption increased.

Wild boars can cause crop damage and are vectors causing infectious diseases. Thus, population management is essential to mitigate the damage. Because home range and habitat selection is important for the management of target species, accurate spatial data would provide valuable information to establish population management scheme. In this study, we investigated the home range and habitat selection of wild boars and aimed to help implement effective population management. We captured seven wild boars in central Gifu Prefecture, Japan, and monitored each individual from October 2020 to June 2022. We calculated the home range size and investigated environmental characteristics during daytime and nighttime. The home range sizes estimated from the minimum convex polygon method ranged from 0.32 to 28.51 km². Moreover, wild boars avoided anthropogenic environments during the daytime and selectively used areas in the cropland category during the nighttime. Therefore, wild boars had narrow home ranges depending on the anthropogenic environments. Consequently, wildlife managers could reduce agricultural damage caused by wild boars by managing bamboo forests and abandoned cultivated lands in the rural landscape. For infectious diseases, moreover, they should implement countermeasures against wild boars around areas where infectious diseases are endemic.

We examined the food habits of raccoon dogs (Nyctereutes procyonoides) at an urban high school in Saitama, Japan. The study place is surrounded by residential areas but is adjacent to a pond. Fecal samples (n = 126) were collected from January to December 2022 and analyzed using the point frame method. Fecal composition was diverse in winter, including leaves, fruits, seeds, and artificial materials. In spring, the proportion of Japanese toads (Bufo japonicus formosus) and insects increased, whereas in summer, proportion of hackberry (Celtis sinensis) fruits, insects, and red swamp crayfish (Procambarus clarkii) increased. In autumn, fruits of hackberry and muku tree (Aphananthe aspera) were predominant. Consumption of toads and swamp crayfish suggests that the raccoon dogs are opportunistic feeders. We recovered seeds from only ten species, including fruits from five wild plants; these numbers were lower than those reported previously in rural areas of the same district, where raspberries (Rubus spp.), mulberries (Morus spp.), and Eurya japonica have often been recovered at great proportions. A wide range of artificial materials were recovered but in low quantities. These results reflect the characteristics of the study area, which is an urbanized environment with limited trees and adjacent to a pond.

Yawning is defined as an involuntary behavior with breathing, characterized by a slow opening of the mouth with inhalation, followed by a maximum gaping phase, and ending with a short exhalation and closing of the mouth. Recent reports on yawning in marine mammals (common bottlenose dolphins and a dugong) have challenged this definition because these marine mammals yawn underwater without breathing. However, yawning in marine mammals has only been studied in captive conditions, which indicates the possibility that yawning is an abnormal behavior in captive animals. Here, we report yawning in free-ranging wild Indo-Pacific bottlenose dolphins off Mikura Island, Japan. Five yawnings that occurred between 8:00 am and 10:30 am were identified from 1816 hours of video data. The dolphins in this population may exhibit more resting behaviors in the morning, which implies that yawning in this population occurred in resting states that required arousal. This is the first reported observation of yawning in Indo-Pacific bottlenose dolphins. The occurrence of yawning in a wild population suggests that it is an innate behavior, rather than abnormal behavior, in dolphins.