Changes in the abundance of birds in relation to small rodent density and predation rate in Finnish Lapland

The relationships between breeding bird numbers, small rodent density and predation on birds' nests were studied in Finnish Lapland in 1966–87. The cycle length of small rodents was 4–¸5 years. There was a close association between small rodents and the number of Redstart pairs breeding in accessible sites in mountain birch forest, but not with Pied Flycatcher pairs breeding in protected sites. The Redstart population seemed to recover from predation pressure in about 3 years. In alpine heaths, but not in birch forests, the density of several bird species correlated with small rodent density.