Formation, maintenance, and dissolution of winter nesting groups of Siberian flying squirrels

Pteromys volans is asocial; however, individuals temporarily form communal nesting groups in tree cavities during winter. It was anticipated that behavioural keys could be identified to facilitate the transition between living a solitary and gregarious lifestyle. Understanding the processes of formation, maintenance, and dissolution of a nesting group of P. volans may help to resolve the dynamics of communal nesting in rodents. We tracked the nesting behaviour of P. volans in two cavity nests from September to April in 2020–2021 and 2021–2022 using passive integrated transponder tags and infrared video cameras. Twelve males and nine females used these nests, and the nesting group originated from the presence of at least one male and one female. The nesting group was maintained from autumn to early spring. Although the group members changed frequently, causing fluctuations in group composition, stable principal individuals were retained. The nesting group dissolved during March–April, suggesting that this may be related to mating behaviour. These findings provide valuable insight into the sociality of P. volans .