Will the Norwegian Lemming Become Endangered if Climate Becomes Warmer?^*

* A version of this paper was presented at the Circumpolar Ecosystems in Winter Symposium, 16-21 February 1990, Churchill, Manitoba, Canada.

Abstract

The Norwegian lemming, Lemmus lemmus (L.), the only endemic vertebrate species in Fennoscandia, normally lives in alpine tundra habitats. During population peaks wandering lemmings may settle in forests, but they do riot persist there. Lemmings are adapted to winter conditions, so for them summer conditions appear more critical than winter. At Kilpisjärvi, Finnish Lapland, fluctuations of five microtines have been monitored since 1946. In the 1980s, lemmings have been less abundant than previously. Results of annual trapping in June/July since 1960 are presented. Lemmings may reproduce at any season and commonly do so under snow. Mosses form the principal food item most of the time in all habitats and seasons. The proportion of mosses in diet diminishes toward the end of the breeding season; when their amount increases, reproduction begins. Since mosses grow in arctic areas during winter, lemmings have fresh food available all the year. In Fennoscandia the coldest environments are not in the northernmost parts owing to the warm Gulf Stream. Hence, as climate gets warmer, arctic species cannot retreat north and may become endangered. If changes are too rapid, the extinction of the Norwegian lemming seems inevitable.