Selection of den sites by wolves in boreal forests in Finland

Very little is known about den site selection by wolves in European boreal forests. We examined the selection of den sites by wolves in central-eastern Finland, where the wolf population has markedly increased over the last 10 years. We found 26 dens belonging to 12 packs where at least one wolf had been collared as part of a long-term ecological study of the wolves in the study area. Generalized linear mixed effect models (lmer) were constructed to explain the location of den sites in terms of their distance from human-modified areas such as built-up areas, roads and agricultural land. Natural factors such as forest type, ground vegetation and the presence of a water source were also considered. Our results highlighted the significance of human-modified areas in breeding site selection by boreal wolves in boreal forests. The results also indicated that hiding cover and sight distance are highly important factors for den site selection, whereas the forest type was of negligible importance.