Millennial-scale oscillations in the Kuroshio–Oyashio boundary during MIS 19 based on the radiolarian record from the Chiba composite section, central Japan

Marine isotope stage (MIS) 19 is considered to be the best orbital analog for the present interglacial. Consequently, clarifying the climatic features of this period can provide us with insights regarding a natural baseline for assessing future climate changes. A high-resolution radiolarian record from 800 to 750 ka (MIS 20 to MIS 18) was examined from the Chiba composite section (CbCS) of the Kokumoto Formation, including the Global Boundary Stratotype Section and Point for the lower–middle Pleistocene boundary on the Boso Peninsula on the Pacific side of central Japan. Millennial-scale oscillations in the Kuroshio warm and Oyashio cold currents were revealed by the Tr index, which is estimated using a simple equation based on radiolarian assemblages. The estimated Tr values ranged between 0.1 and 0.8 for MIS 18 through MIS 19, with minimum and maximum values corresponding to values observed off present day Aomori (41°N) and the Boso Peninsula (35°N), respectively. The observed patterns tended to be synchronous with the total radiolarian abundance associated with their production. Multiple maxima in radiolarian abundance occurred during periods of the Oyashio expanded mode before 785 ka and during periods of Kuroshio extension after 785 ka in MIS 19. Such increases in radiolarian abundance with the Kuroshio extension during MIS 19 are likely related to improvements in nutrient and photic environments with the development of a two-layer structure along the Kuroshio–Oyashio boundary zone. A similar pattern of millennial-scale climatic changes was also recognized in a precipitation record from the Sulmona Basin in central Italy, suggesting a close relationship with the CbCS record as a result of a large-scale climate system similar to the Arctic Oscillation in the northern hemisphere.

Food habits of two species of tube-nosed bats, Murina hilgendorfi and Murina ussuriensis, in Hayakawa, central Japan

Knowledge of food habits is essential for understanding the life history of a species; however, such information about the enigmatic Murina genus of bats is little known. In this study, we examined the food habits of Murina hilgendorfi and Murina ussuriensis over four years in Hayakawa, central Japan, using traditional morphological fecal analysis. Fragments of arthropods of six orders (five identified families), and of five orders (five identified families), were found in the feces of M. hilgendorfi and M. ussuriensis, respectively. Both species consumed wingless arthropods (caterpillars and spiders), insects that rarely fly (ground beetles and bush crickets), or diurnal insects (dragonflies and hoverflies; i.e., that are resting at night) during the night, which is a clear indication of gleaning behavior in these bats. In spring, the large-bodied M. hilgendorfi more frequently consumed hard-bodied insects such as beetles and bush crickets, whereas the small-bodied M. ussuriensis more frequently consumed soft-bodied insects such as caterpillars, moths, spiders, and dipterans, suggesting that the body size difference influences their food habits, which may have contributed to food resource partitioning between these closely related bats. For M. hilgendorfi, beetles were the main prey in spring and autumn, while caterpillars and grasshoppers were more frequently consumed in spring and autumn, respectively, suggesting that they may have changed prey items according to seasonal fluctuations in food availability. To our knowledge, this study provides the first record of differences in the food habits of these two species.

Recalcitrant Interactions : Semiotic Reflections on Fieldwork among Mountain Ascetics

This article explores issues related to ethnographic research, such as “otherness” as a form of relation, the researcher’s position, and the difference between anthropological and native knowledge, leading to the production of ethnographic data that can undermine previously established models. In order to approach these issues, I will refer to the notion of “recalcitrant subjects”, coined by I. Stengers, and based on the idea that we should turn our attention to objects of analysis that are capable of raising new questions, forcing the researchers to reorganise their instruments and theoretical perspectives. Using the interaction regimes formulated by E. Landowski, I will analyse from a semiotic perspective my own field research, conducted within the mountain ascetic group Tsukasakō in Katsuragi, central Japan. The article shows how, far from being based on forms of communality and undifferentiated reciprocity, ethnography and sociality always involve heterogeneous actors and can only emerge from interactions that are inherently recalcitrant.