| Abstract [eng] |
Small mammals are indicators of forest ecosystem sustainability and play an important role in many other ecosystems worldwide. Diversity, abundance, dominance, sex and age structure, and other indicators of the small mammal community are influenced by environmental conditions. Changes in the structure of vegetation, undergrowth, composition of tree crown cover or forest litter affect small mammals communities. Colonies of great cormorants are probably the fastest and most strong environmental factor in our climatic zone. Complex environmental effects of great cormorants lead to enormous ecosystem transformation. In this work the effects of cormorants on mammals were scientifically evaluated for the first time. We found, that the initial positive effects of cormorant colonies on the ecological and biological parameters of small mammals are changed to negative when colony size reaches a critical level. Influence of cormorants on the accumulation of heavy metals and other chemical elements in mammalian tissues was evaluated, and a stable isotope ratio analysis of carbon and nitrogen was performed. Novelty of our investigation was in evaluating the immediacy of the impact of the cormorant colony on small mammals. The results for the first time showed how fast biogenic pollution is transferred and what its consequences are to small mammal ecology. We also observed changes in seasonal and daily activity patterns of mammals in the colonies of cormorants during bird breeding time. |
