Relationship between the Onset of Winter and Collared Lemming Abundance at Churchill, Manitoba, Canada: 1932-90

Ten periods of high abundance and nine periods of low abundance of collared lemmings (Dicrostonyx richrdsoni) at Churchill, Manitoba, Canada, were determined from 1932 to 1990 using published and unpublished trapping studies. Response functions were used to relate extremes of lemming abundance to temperature and precipitation in the preceding 24 months. Good correspondence was found between conditions around fall freeze-up and both high and low collared lemming abundance. This indicates that far-from-average temperature and precipitation may moderate the abundance of collared lemmings. During spring and fall the southern tundra, such as at Churchill, has a high frequency of annual freeze-thaw cycles, indicating that this area may be more stressful to lemmings than cooler climates with fewer freeze-thaw cycles.