Beavers make dams for a variety of reasons. Some of the most important include: Protection from the river – Often, beavers construct their dens, called lodges, in the banks of rivers. Fast-moving water would quickly wash these homes away without a dam to slow the stream’s progress. Safety from predators – Dams create small ponds that cover the entrance to a beaver’s lodge. This allows the animal to enter and leave its home undetected by bears, wildcats, other predators. Access to food – Beavers build dams to submerge bushes and trees, which compose most of the pest’s diet. This makes vegetation easy for beavers to access but more difficult for competing wildlife to reach.