Seasonal changes in activity patterns of Japanese flying squirrel Pteromys momonga

•Seasonal changes in activity patterns of Pteromys momonga were surveyed.•P. momonga showed nocturnal activities through the study periods.•Bimodal/trimodal activity peaks were found in temperate/cold seasons, respectively.•This seasonal changes could reduce energy loss in cold temperatures. Seasonal changes of activity patterns are an important survival strategy for several species. Seasonal changes in the activity patterns of Japanese flying squirrels (Pteromys momonga) were studied at Daibosatsu Mountain on Honshu Island, Japan from 2 June to 20 November 2007 and 11 April to 14 November 2008, to discuss their survival strategy based on the change. Activity patterns were assessed using long-term sensor camera traps at 214 sites for 14 months of a 2-year period. The cameras were placed for a total of 7317 camera trap nights over which total of 90 photographs of this species were collected from 22 of the 214 sites. Although distinct nocturnal activity was detected throughout the study period, activity patterns differed between temperate (June–September) and cold (April, May, October, and November) seasons. So, activity peaks were found to be bimodal during the temperate seasons and trimodal during the cold seasons. It is possible that the squirrels reduce their activity times per bout during the cold seasons to reduce energy loss arising from prolonged exposure to cold temperatures, as a survival strategy.