European Beavers (Castor fiber L.) dams rebuild intensity

Abstract

European Beaver (Castor fiber L.) was reintroduced in Lithuania on 1947. Population growth was quite rapid ant there were about 6000 beavers on 1970. Nowadays beavers population in Lithuania is about 40 000. Beavers have a possibility to affect the environment where they live by building dams, lodges, making caves systems, changing water level. Because of being such an active environmental former beaver has a huge indirect impact for forest and agricultural fields – higher water level usually causes damage for forest trees or crops. Thera are different studies about this beaver’s ability to change environment and to build dams, lodges. Explanations why it is needed for this species now is clear, but still there are question how can these animal plan, organise and improve their ability to build. The aim of this research is to find out if dams rebuilt activity intensity differs during different year seasons and is it affected by the beaver’s family size in current place. According to our findings, the beginning of damp rebuilt and total damp rebuild depends on year season – on fall season it takes 4 times less time. In addition to this, family size has an effect – bigger families rebuilt dams faster. Usually beavers do this job from midnight to 2 a.m. on fall season.