Home WORLD How & Why Do Beavers Build Dams? Ecosystem Engineers

How & Why Do Beavers Build Dams? Ecosystem Engineers


Beaver dam building is a pretty fascinating topic. Unfortunately, no-one really knows how beavers evolved, let alone how dam building behaviour evolved.Beavers appear to build dams for two main reasons: protection from predators and to provide a stable source of food and easy access to it for themselves.

source/image: PBS 

This offers some clues about how they evolved – almost certainly as a response to selection pressures for these two reasons avoid predation, obtain food.These dams are made of branches stuck down into the stream bed and then built up with a thick mortar of mud, gravel and interwoven branches./nps

The dam is constantly maintained to keep the water at the same level for beaver comfort and security.Beaver dams are sometimes maintained and expanded over many generations. They can be up to 1,000 feet long and 15-20 feet high.


Beavers are famous for their logging skills, chiseling down trees up to 3 feet in diameter. However, they are not clever enough to aim a tree’s fall and on rare occasions a beaver has been crushed by a tree trunk. The beaver is a very powerful animal, capable of dragging a heavy log through the woods and down into the water.