Rodents are the most abundant mammals on Earth, prevalent on all continents except Antarctica, and they fulfill important ecological roles in various ecosystems. Recent progress in high-throughput DNA-sequencing technology has enabled identification of diet components in various environmental samples, such as feces or stomach contents, through DNA metabarcoding. Studies using this method have begun to clarify the diets of small, nocturnal, and elusive rodents. This review summarizes previous studies that used DNA metabarcoding to clarify the diets of native or exotic species in Rodentia to understand progress and unresolved problems in such analyses. Furthermore, the methodology of dietary DNA metabarcoding in rodents is discussed, together with issues that should be taken into consideration. Finally, future perspectives and directions to be considered in the use of DNA metabarcoding in dietary studies of rodents are discussed.

Published online 6 December, 2024; Print publication 31 January, 2025

In Southeast and South Asia including Myanmar and Bangladesh, the house shrew (Suncus murinus) is widely distributed and consists of multiple lineages of mitochondrial DNA. However, there has been no morphometric investigation among such lineages, despite the obvious recognition of large variation in their body size and shape geographically. To elucidate morphological differences among local populations in reference to multiple lineages of S. murinus, we conducted geometric morphometrics to investigate skull morphological variations focusing on highly diverged Myanmar and adjacent Bangladesh and Vietnam populations. Our findings indicate that skull shape changes can distinguish adjacent lineages, and some individuals represent intermediate forms between the two geographically adjacent lineages. The results also represent several overlaps of skull size and allometric shape changes among Myanmar populations, suggesting the presence of intermediate individuals due to hybridization. Additionally, allometric shape changes were observed in the sites of attachment of muscles or tendons between the cranium and the mandible suggesting an association with piecing or decaying soils and woods. Our findings provide fundamental insights into the skull morphological features of S. murinus, which contributes to a more comprehensive understanding of the evolutionary processes of morphological variation in the house shrew.

Published online 10 September, 2024; Print publication 31 January, 2025

We investigated semen quality and seasonal changes in serum testosterone (T) concentrations in a male false killer whale, Pseudorca crassidens, under managed care. Semen was collected 107 times in 27 sessions for 22 months between June 2018 and April 2020 and analyzed for semen volume, sperm concentration, total motility, progressive motility, viability, and kinetic rating. Serum T concentrations in blood samples were measured by fluorescence immunoassay 1–4 times a month for routine health assessments from April 2016 to May 2022. The fourth and fifth ejaculates of each session were typically lower in volume but had higher values for all other tested parameters. The monthly mean serum T concentration showed a seasonal change; it began to increase in September, peaked between November and January (i.e., fall to spring), and declined until August (i.e., in late summer). This is the first report on semen quality in false killer whales, where we observed seasonal changes in T concentrations and established that the fourth and fifth ejaculates of a session yielded good-quality semen.

Published online 6 December, 2024; Print publication 31 January, 2025

To clarify the species of mange-causing mites and their genetic characteristics, we performed morphological and molecular identification of mites inducing mange-like symptoms on a Japanese serow found in Shikoku, Japan. We identified two mites as Sarcoptes scabiei and Chorioptes japonensis. On a Japanese serow with mange-like symptom, only one female S. scabiei individual was found, whereas numerous C. japonensis were present. Therefore, it is plausible that infection with C. japonensis caused severe symptoms on the Japanese serow. Chorioptes japonensis were detected in four of five samples from the ears of Japanese serows in western Tokushima. The wide distribution and host specificity suggest that the Japanese serow may be the natural host of C. japonensis.

Published online 16 October, 2024; Print publication 31 January, 2025

To investigate diets of two sympatric carnivoran species, a leopard cat (Prionailurus bengalensis) and a yellow-throated marten (Martes flavigula), in Mt. Jeombongsan, Korea, we elucidated their diet compositions using fecal DNA. Their feces were collected from October 2015 to October 2018. After extracting DNA from fecal samples, the mitochondrial 12S rRNA gene of vertebrates and the rbcL regions from plants were amplified. Prey DNA was detected by cloning-based sequencing using blocking primers. A variety of rodents such as Muridae and Cricetidae and birds such as Passeriformes and Galliformes were frequently detected in feces of leopard cats and yellow-throated martens, suggesting that these taxa were important prey of the two carnivoran species. Regarding plant food sources, genus Prunus was frequently detected in feces of the leopard cat and genus Actinidia in feces of the yellow-throated marten, indicating that these two Carnivora species were not exclusively carnivorous. The maximum numbers of vertebrate prey taxa were estimated using rarefaction curves. Our results suggest that both species have roles as top predators in Mt. Jeombongsan, demonstrating significant differences in the diets of the two sympatric Carnivora species.

Published online 28 November, 2024; Print publication 31 January, 2025

Sika deer (Cervus nippon) cause substantial economic losses in the Japanese agricultural sector. To control animal behavior, knowledge of the sensory and behavioral characteristics of the target animals is necessary. Therefore, to develop effective strategies, we investigated the visual acuity of sika deer (one male and one female) through an operant conditioning experiment. Within a 4 × 8 m closed room, we presented one deer with a positive stimulus (Landolt ring) and a negative stimulus (ordinary ring) on a pair of panels (0.8 × 0.6 m) positioned at a distance of 3 m. Visual acuity was determined by varying the size of the ring. Each session comprised 20 trials, with the criterion for successful discrimination being a minimum of 75% correct choices by the end of the session over three consecutive sessions (P < 0.05, chi-square test). In the discrimination experiment, they were found to be able to discriminate the Landolt ring from the ordinary ring with visual acuities of 0.02, 0.04, 0.08, and 0.16. However, they were unable to distinguish between these rings at a visual acuity of 0.24. Thus, our findings indicate that sika deer have a visual acuity of up to 0.16, comparable to that of sheep.

Published online 6 December, 2024; Print publication 31 January, 2025

This study investigates the socio-economic impacts of human-elephant conflict (HEC) in the Betla Range of Palamau Tiger Reserve. The Betla Range, characterized by frequent human-elephant interactions, provides valuable context for exploring these complex conflicts. Aimed at understanding the perception and consequences of HEC on local communities, this research utilizes a semi-structured questionnaire survey among 108 villagers to gather perspectives of the locals on their experiences with HEC and its resolution. In addition, we have also conducted Risk mapping exercises to understand the perceived gravity of HEC as a threat compared to other risks that the locals face. The research highlights frequent encounters with elephants, especially during monsoon rice-farming season, and nocturnal nature of elephant raids, the preference of elephants for ripe crops, and the limited effectiveness of community-based mitigation strategies leading to substantial crop and property damage. The findings revealed a high awareness of government compensation policies among villagers, although a significant majority report received inadequate or no compensation due to the complexity of the process. Risk mapping exercises also showed that animal raids, in particular, crop raiding by elephants was perceived as the greatest risk by the locals.

Published online 25 December, 2024; Print publication 31 January, 2025

The pollination modes of plants vary among regions owing to faunal variations; however, knowledge of pollinators in tropical montane Asia is insufficient. Here, we elucidate the pollination system of Mucuna thailandica (Fabaceae), a plant endemic to the montane forest of Thailand. The genus Mucuna exhibits a distinctive pollination mechanism called “explosive opening″. The stamens and pistils of Mucuna flowers are covered by a pair of keel petals, and pollination is only possible when a flower is opened by a pollinator, which exposes stamens and pistil. In bagging experiments, unopened M. thailandica flowers did not bear fruit, indicating that an explosive opening was necessary for successful pollination. Automatic camera surveys showed that squirrels (Callosciurus finlaysonii/erythraeus complex and Dremomys rufigenis), masked palm civets (Paguma larvata), and northern treeshrews (Tupaia belangeri) opened the flowers explosively. Among them, the C. finlaysonii/erythraeus squirrels opened flowers most frequently, and three flowers bore fruits. Thus, C. finlaysonii/erythraeus squirrels may be effective pollinators of M. thailandica. Opening the flowers grants pollinators access to a large volume of nectar with a high sugar concentration as a reward. Our findings suggest that the role of nonflying mammals as pollinators in tropical Asian montane forests may be greater than previously thought.

Published online 28 November, 2024; Print publication 31 January, 2025

The lesser Japanese mole (Mogera imaizumii) is mainly distributed in eastern Honshu, the largest island of the Japanese archipelago. From central Honshu to the western islands, on the other hand, is almost exclusively inhabited by their closely related species, the large Japanese mole (M. wogura), with several allopatric fragmented populations of M. imaizumii. Our study aims to analyze the phylogenetic relationships and historical dynamics of M. imaizumii populations in western Japan using mitochondrial cytochrome b gene (Cytb) sequences (1140 bp). The findings indicate that the populations in western Honshu (Mt. Hiba), Shikoku (Mts. Ishizuchi and Tsurugi), and two offshore islands (Dogo and Shodoshima) belonged to a distinct lineage (Mim-IV) that diverged about 700 000 years ago from the three major lineages previously identified in eastern Japan and the Kii Peninsula. Mim-IV harbored closely related Cytb sequences within the lineage, with genetic divergences occurring at least 200 000 years ago. We hypothesize that the genetic structures of M. imaizumii and M. wogura in western Japan may have been formed by the repeated expansion and contraction in response to the recurrent environmental fluctuations during the 100 000-year Quaternary glacial cycle.

Published online 25 December, 2024; Print publication 31 January, 2025

The response of mammals to anthropogenic disturbance in highly biodiverse regions is a continuing concern for conservation as land use change continues to increase. Shrews are usually associated with low forest disturbance by human activity; however, this has been poorly documented in tropical regions of the New World. We present preliminary data on the habitat and abundance of two shrew species in a forest-agricultural ecotone in the Trans-Mexican Volcanic Belt. Shrews were monthly sampled (October 2018 to May 2019) from an undisturbed pine-oak forest, the forest edge, and a cultivated area. We collected 37 individuals of Cryptotis alticola (5) and Sorex ventralis (32), mainly during the winter (January–February 2019). Shrews were obtained from the undisturbed pine-oak forest (56.76%) and the forest edge (43.24%) and did not occur in cultivated areas. These results show a similar response to habitat disturbance observed in higher latitudes, with an apparent avoidance of cultivated areas. We conclude that shrews are sensitive to human-induced habitat transformations in the Trans-Mexican Volcanic Belt. Our findings represent the first data on abundance and local distribution for C. alticola, a species in the IUCN Data Deficient category.

Published online 6 December, 2024; Print publication 31 January, 2025