The lemming community on the lichen-heath tundra at Churchill, Manitoba

Abstract

During 1984, a community of small mammals located within an "island" of lichen-heath tundra in the forest-tundra near Churchill, Manitoba was studied. Dicrostonyx richardsoni shares the area with two eurytopic species; Sorex cinereus, Microtus pennsylvanicus and three Boreal species; Phenacomys intermedius, Clethrionomys gapperi, and Synaptomys borealis. Of the three most abundant species, D. richardsoni was trapped in the upland sites along with P. intermedius, and M. pennsylvanicus was trapped in the lowland sites. In comparison to other populations of the species, the Churchill population of D. richardsoni is residing in a community with more southern species of small mammals. The high density of the burrows, and the slow rates for peat accumulation shows that most of the burrows date to a previous period. D. richardsoni may have been more widespread during colder climatic periods such as the Little Ice Age. P. intermedius, C. gapperi, and S. borealis are not characteristically found on tundra and, therefore, may be recent invaders encouraged by the recent favourable climate.