The influence of fire on small mammal populations was investigated in the taiga of southeastern Manitoba. Small mammals were sampled by annual removal trapping in six different habitats over twenty-five years at Taiga Biological Station (TBS). Changes in temporal patterns of short-term abundance and long-term population synchronicity were investigated for fluctuating numbers of small mammals. The southern red-backed vole (Clethrionomys gapperi),the deer mouse (Peromyscus maniculatus), and the masked shrew (Sorex cinereus), were the three most common small mammals captured. Examination of population fluctuations revealed that while fire-induced changes in food availability, cover and moisture were likely responsible for differences in small mammal abundance, populations of individual species were alternatively affected by unknown, large-scale, synchronizing influences. This discovery became evident through the common occurrence of similar peak abundance years for C. gapperi, regardless of habitat-type or distance between sampling sites. Additionally, the examination of annual combined small mammal biomass revealed a distinct pattern, with a repetitive maxima occurring every 3- to 4- yrs at TBS across all six sites...