Effect of rainfall on nocturnal activity of the Japanese dormouse

The response of small rodents to rainfall is largely species-specific. There is a need to widely survey the effects of rainfall among varied rodent species, particularly arboreal rodents to accurately understand their response to rainfall. Therefore, in this study, we examined changes in the activity patterns of Japanese dormice Glirulus japonicus in relation to rainfall. We undertook extensive camera trapping for 2 yr to collect data on dormouse activity. During all 63 camera-trap detections (i.e. 24 on rainy nights and 39 on nights without rain) using cameras set at 214 sites, dormice demonstrated perfect nocturnality. Dormice were active throughout the nights when there was no rain; however, on rainy nights, their activity tended to be limited to close to sunset. Our results provide important evidence that rainfall limits the activity of Japanese dormice. In Japan, precipitation has increased with recent climate change; thus an increase in precipitation in the future could increasingly limit the periods of activity of the Japanese dormouse.