Novel in-situ observations on the diel surface activity of the Romanian hamster, Mesocricetus newtoni (Rodentia, Cricetidae), during pup rearing

The Romanian hamster Mesocricetus newtoni is a threatened and cryptic species, with a distribution limited to North-eastern Bulgaria and South-eastern Romania (Dobruja region). Current literature does not provide sufficient data regarding diel activities and behavior of this species, especially under field conditions. In this context, one female M. newtoni, during the rearing period of her four pups, was monitored for ten days using camera traps. For each documented activity, the date, time, age of the individual, type of activity, and duration were recorded. In total, from the 26140 media files, 72968 seconds were recorded as active behaviors. Data analysis revealed that diurnal activity was predominant and documented for all monitored days; however, the animals spent more time per each activity during the night. The nocturnal activity was present but erratic, without significant patterns. No significant differences were observed in the median duration of activities of the adult compared to the immature individuals. Both the adult female and pups spent time exploring the burrow entrance, especially during the day, but immatures were more reserved to leave the burrow than the female. The female used four burrows for rearing the pups. During this time, food storage behaviors and transferring of immatures between burrows, as well as the weaning of the pups were documented. This study demonstrates that M. newtoni exhibits significant diurnal activity, at least in certain ecological and physiological conditions.