Observations on a Lemming Movement in Jamtland, Sweden, in Autumn 1963

Abstract

Field observations were made of a lemming eruption in Jämtland, Sweden, in 1963. A typical mountain habitat, a place along the migration route, and the tip of a peninsula where the movement was finally halted were visited. There was no evidence of excess numbers of lemmings in the first area. Masses of lemmings had, over a period of several weeks, passed through the second area and some were still present. The vegetation was not depleted, nor was there evidence of mass mortality. In contrast, the third area had a high lemming density, depleted pastures and high mortality by drowning. Details are given of distribution of animals in different regions and the corresponding behavior patterns. Animals on the move appeared to follow routes of previous migrants. They always moved as individuals and not in groups. An exceptional incident of shoreline “massing” is described.