Seasonal Variations in Circadian Rhythms of Deer Mice, in Northwestern Canada

Abstract

Circadian rhythms of Peromyscus maniculatus were studied at Heart Lake, Northwest Territories, in winter and spring of 1965-1966. Daily peaks of activity were of longer duration and higher amplitude in spring than in winter. In winter deer mice were frequently observed in torpor and most activity occurred at night. In spring daily peaks of activity began before dark and extended 4 to 5 hours into daylight of the next morning.