Predation on artificial ground nests placed along four transects (alderwood, fallow, pine forest and fallow-forest edge) was studied in 1998–2009. On average, a 25.4% increase in overall predation rate was observed over the study period and increasing predation occurred at all sites. Mean multiannual predation rate differed up to 2.3-fold between transects and was highest in the alderwood and lowest in the fallow area. Despite that share of particular predators in depredation of nests was not random with respect to the studied habitats, high year-to-year variation in the pattern of predation was recorded. Between-year and between-transect changes in predation pressure were responsible for 48% of overall predation variability. Predation in one, randomly selected year was weakly related to averaged data from all 12 years, which indicates that short-term studies employing artificial nests can significantly over- or underestimate the contribution of particular species to overall predation.