Habitat fragmentation, seasonality and predation affecting behaviour and survival of bank voles Myodes glareolus

Abstract

Habitat loss and fragmentation are the main causes for innumerable population and species having become threatened and for many of them already having gone extinct. Declines in species richness or populations are primarily caused by habitat loss, but habitat fragmentation, which subdivides populations into smaller units, is also important factor. Habitat fragmentation inevitably affects behaviour, space use and social interactions of individuals. These are likely to form essential part of the mechanism behind observed population declines. In this thesis I have studied the role of behaviour and space use of animals in fragmented landscape in a series of enclosure experiments. Summer experiments (I-III) concentrate more on behavioural effects of fragmentation whilst the winter experiments (IV-V) focus on behaviour, survival and onset of breeding with food supplementation and predation risk. I found that increased fragmentation led to increased risk-taking in the case of male bank voles and the hunting weasel when resources were distributed into separate patches. Female bank voles tended to stay inside the habitat patch and closer to their nest in more fragmented landscape. During winter snow evened out differences between habitat and matrix, but during spring when the breeding season starts, males in the fragmented treatment needed to take more risks by crossing the open matrix. Food in winter is important factor for the condition, survival and onset of breeding in bank voles. Surprisingly, also mere predation risk during winter had significant effect on vole population density, condition, survival and onset of breeding in the spring. To conclude, habitat fragmentation have direct survival and fitness consequences for individuals and it changes individual interactions, but direction of these effects depend on fragmentation types and duration and scale of experiments.