[Diurnal activity rhythm of Clethrionomys rufocanus]

The diurnal activity rhythm of Clethrionomys rufocanus was studied under three different food conditions in a laboratory. The activity occurred both in the daytime and at night, but mainly at night (19:00-4:00). The mice fed with Mouse food exhibited six small peaks in their daily activity, and those fed with grass or hay exhibited seven, but the peak of the out-nest night activity was 2-3 hours earlier. The activity amount of out-nest was 30,518.0 +/- 3,694.9 s for those fed with grass, the next was 21,811.7 +/- 2,288.0 s for those fed with hay, and the least was 15,038.0 +/- 666.0 s for those fed with mouse food. The activity amount of feeding was 10,867.3 +/- 1,612.1 s for those fed with grass, much more than those fed with mouse food and hay. The activity amount for drinking was 988.5 +/- 79.1 s (fed with hay), 568.9 +/- 60.9 s (fed with mouse food) and 139.3 +/- 47.2 s (fed with grass).