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Small mammals communitis in the surrounding of town České Budějovice and the common voles (Microtus arvalis) population ecology
KAPOUN, Ondřej
The changes in the small mammals abundance were studied on the total of eight plots in three different habitats situated on three different localities during the period between autum 2004 {--} spring 2006. The effects on small mammals comunities composition were odserved.Also the effect of locality, habitat type, vegetation structure and avian predation on vole numbers and reproduction parameters was assessed. The impact of habitat type on population dynamic was also examined. The highst numbers of small mammals species and the highst species diversity were found on the set-aside-plots. This may be explained by species-specific relationship to vegetation structure and also probably heterogenity of vegetation cover. The predation by Common Kestrel (Falco tinnunculus) and Common Buzzard (Buteo buteo) had no significant effect on vole numbers. In addition, no differences were found in population dynamics between localities. However, there were some differences between habitat types: the trefoil-fields serve as source patches of individuals in breeding season (63.08% of sexually active voles; mean fecundity 3.6 juv./female) while set-aside-plots are probably sinks (47.16% of sexually active voles; mean fecundity 1.3 juv./female). This may be explained by food quality. Set-aside-plots seem to have an important role on the overwintering of individuals, as in the rest of the habitats local population could become extinct during winter. This might be due to some protective influence of plant biomass, with restrain the impact of the winter season on vole survival. The role of habitat types (sink/source) is changing during season. Neverthelles, "trefoil-field" patches, influence magnitude of vole number fluctuations while set-aside-plots are important for maintenace and stability of vole metapopulation. The bachelor thesis includes a literary review, containing a a brief description of several basic hypotheses offering explanation of the causes and the maintenance of the population cycles. Another section of the review concerns variation in small mammal population dynamics on the geographical and local level. Some attention is also paid to changes in the small mammal demographics in the course of a population cycle.
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