Mice, voles and lemmings are key species in arctic and temperate ecosystems. They play an essential role as major plant eaters and main food source for the predator community involving rodent specialists such as weasels and owls, and generalists such as foxes, marten, lynx, wolverine, many birds of prey and even skuas. Through their effects on plants and predators, the small rodents also exert major influence on other herbivorous species such as hare, ptarmigan and possibly reindeer. As is well known in folklore, the small rodents undergo regular fluctuations in numbers. These fluctuations span several orders of magnitude and have a major impact on the ecosystem as a whole, driving or interacting with similar fluctuations in predators and other herbivorous species. The project aims to improve our understanding of the mechanisms behind these still enigmatic fluctuations. A breakthrough in understanding the small rodent fluctuations is a breakthrough in understanding the functioning of the entire arctic ecosystem.

The study of small rodent population dynamics is a field with strong traditions in Norway and Fennoscandia. Pioneering work on lemming fluctuations was done by the late Robert Collett, a previous distinguished member of our Academy and the Zoological Museum of the University of Oslo. His work inspired a founding father of modern ecology, Charles Elton, to work on the rodent fluctuations.
The general objective of the project is to produce a much-needed synthesis of the population biology of small rodents.