Summer Activity Patterns of Three Rodents in the Southwestern Yukon

Abstract

The small mammal communities of the boforereasl t in the SW Yukona re diverse and little is known about the underlying reasofnosr thisspecies richness. Niche differentiation through staggered periods of activity is one way in which similar species may avoid potential interferencecompetition. In this studyw e describe the activity pattern of three rodents d(teheer mouse, the northernr ed-backed vole, and the singing vole) from thesummer solstice to the autumnaelq uinox. Activity was measured otwn o white spruce plots by checking live-traps at 2 h intervals over a 24 h period. Wedid this at monthly intervals between June and September 1984. The deer mouse was strongly nocturnal throughout the summer, while the northernred-backed vole and the singing vole were active both day andn ight. During the nocturnal period of deer mouse activity, approximately 80% of thered-backed vole population wacs tive, and we conclude that there is e vniod ence of temporal niche differentiationb etween these two species. Only deermice showeda seasonal change ianc tivity pattern. As thed ays became shorter, deer mice became activeea rlier, so that by September they were active 4 h earlier than they were in June.