Nothing compares to the construction abilities of nature’s engineer, the American Beaver. A beaver family alters the environment to suit its lifestyle.
A beaver pair, attracted by the sound of running water, chooses a site along a small stream to build a dam. Beavers construct dams to provide deeper water for their own protection. Although they are strong, beavers are not aggressive, and they would rather escape than fight a predator. These aquatic mammals need water to hide, swim, work, eat, and breed.
To fell trees, a beaver stands up next to a tree supported by its tail, turning its head parallel to the ground. Its chisel-like teeth make two cuts into the wood of the tree trunk, one above the other. Then its upper incisors bite into the wood between the two cuts, while its lower incisors pry out a wood chip. It keeps biting and spitting out wood chips, moving around until the tree trunk falls. Branches are chewed off and carried in the beaver’s front paws or pushed with its head and shoulders into the water to be floated downstream.
Creating a dam starts with a beaver wedging branches into the substrate of a shallow stream. Rocks and mud are added to weigh down the branches. The dam grows wider at the bottom. Openings are deliberately jammed with more sticks or mud until water stops flowing through. A dam built on a swift-flowing stream has a bowed shape that actually strengthens it.
Bank burrows are temporary shelters for beavers while their dam is under construction. Beavers begin to construct their lodge, or home, after the water level rises when the dam is finished. Rocks, sticks, and mud are piled on the bottom of the stream to create the lodge. A dome of interwoven branches rises 6 feet above water, like a medieval castle surrounded by a moat. Beavers chew their way inside, making two underwater entrances. Chambers about 4 feet wide by 2 feet high are created on two levels. The first level is used for eating and as a draining platform for drying wet fur. Twelve inches higher, the second level is the bedroom, padded with shredded bark. Liquid mud covers the lodge outside, drying hard as concrete, except for an open center air hole.
A beaver family can live comfortably inside its lodge, protected from coyotes, wolves, bobcats, and foxes, and feast on its cache of branches stored underwater.