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.