Long-term dynamics of small mammals at Finse

Since 1970 the population fluctuations of small rodents and shrews have been followed by snap-trapping of two 1ha permanent grids at Finse, Hardangervidda, in June/July and August/September. Trapped animals are located to specific trap stations within the grids, and data on their weight and reproductive state are collected. Until the mid 1990s, trapping indicated rather regular fluctuations with quite variable population peaks every 3-4 years. Since the last great peak in 1994, no substantial peak in small rodent populations has been recorded here. A possible explanation for this change in pattern may be related to changes in the climate as mediated through the snow quality in late winter (cf Nature 456: 93-97).