The term "busy as a beaver" is high praise indeed. Beavers are insanely hard-working rodents; a lone individual can cut down up to 200 trees in a single year. Famously, they build sturdy homes — or "lodges" — for themselves out of branches, mud and other materials. They can also make their own large-scale ponds by damming streams.
With a well-placed dam, a beaver family will be able to regulate water flow. On the structure's upstream side, backlogged water may give rise to a standing pond where none previously existed. This not only gives beavers a place to build their lodges, it also affords easy access to surrounding trees. Often, a couple of inches (5 centimeters) or feet (0.6 meters) of water covers the bases of nearby pines and hardwoods that once stood on dry ground. As a result, beavers can swim right up to these trees. They also like to dig canals that branch out of the new ponds, penetrating deeply into the local forests.
However, not all the side-effects are positive. When a beaver dam fails, it's liable to flood towns or farms. The aftermath can be expensive: In the southeastern U.S. alone, these floods are responsible for an estimated $22 million in yearly damages to the timber industry. It's not surprising, then, that many people view beavers as pests. If you've got a beaver problem, know that humane solutions are out there.