The influence of environmental temperature and photoperiod on activity in the red squirrel, Tamiasciurus hudsonicus

The effects of environmental temperature and photoperiod on wheelrunning activity were studied in the diurnal red squirrel, Tamiasciurus hudsonicus. From 1 July to 22 November 1973 eight squirrels were maintained in separate cages in an outdoor shelter. Activity usually began before sunrise in the summer an early fall and after sunrise in the late fall. Wheel-running usually persisted throughout the day and ceased about the time of sunset in the summer and early fall. In late fall cessation frequently occurred after sunset. Neither changes in temperature nor photoperiod were found to separately account for the seasonal changes. Multiparameter analysis of variance was found to be a powerful statistical tool for analyzing the data. Six models for predicting the onset of activity were constructed and tested