Eco Engineers: 5 Animals That Can Reshape Earth's Waterways



Beavers can wreak havoc digging canals and building dams that often block rivers. Dean Fikar/Getty Images

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.

These new beaver-created wetlands provide homes for smaller animals like amphibians. Plus, the rodents' dams make great natural filters, blocking excess nitrogen from our creeks and streams.

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.