Beavers busy getting ready for winter

“A beaver does not, as legend would have it, know which direction the tree will fall when he cuts it, but counts on alacrity to make up for lack of engineering expertise.”

— Ann Zwinger

The slap of a beaver’s tail against water is one of the most unique and startling sounds in nature.

That is what I was thinking when I saw this beaver on the Kootenai Wildlife Refuge route north of the headquarters over-looking Myrtle Creek. The beaver was too preoccupied eating willow branches to be distracted by a gawking photographer.

As I enjoyed watching him for about 30 minutes, he lived up to his namesake and was a “busy beaver.” Then slipped quietly into the creek and was gone without a sound below the ice.

All beavers need water to survive. They live in or around freshwater ponds, lakes, rivers, marshes and swamps. As the largest rodent in North America, the American beaver (Castor canadensis) has evolved exceptionally well to its environment, gnawing through willows and trees to create the dams and lodges that mark their territory. Their altering of waterways impacts numerous other fish and wildlife as well.

A beaver’s home is called a lodge. Lodges are little dome-shaped houses made from woven sticks, grasses and moss plastered with mud. They can be up to eight feet wide and up to three feet high inside. They are built on banks of ponds, on islands or on lake shores, just barely above water level. Many lodges have an underwater backdoor for instant swimming access.

Beavers are good house guests. Their lodges typically contain two dens, one for drying off after entering the lodge under water, and a second, dryer den where the family will live and socialize. They have been known to share their lodges with families of muskrats.

The beaver is a clumsy animal on land, but when it takes to water it propels itself with grace and speed thanks to its powerful webbed hind feet. Beavers have a large, scale-covered tail that helps them maneuver through the water. A mostly nocturnal rodent, beavers build dams of sticks and mud across streams and can be found living in ponds, small lakes, streams and rivers. A strict herbivore, the beaver eats a combination of woody and herbaceous species, such as mountain alder, aspen and willows.

Beavers’ front teeth are orange ... and not just because they have terrible dental hygiene. To gnaw through tree trunks, they need extra-strong teeth. Fortunately, their tooth enamel contains iron, which makes them incredibly strong, sharp, and orange. Because the orange enamel on the front of their teeth wears away more slowly than the white dentin on the back, a beaver’s teeth self-sharpen as he chews on trees.

Beavers build dams for a myriad of reasons, and one is so that the lake behind it will grow deep enough to ensure it doesn’t freeze all the way through during the winter. This bit of temperature control is especially crucial because beavers anchor a food cache to the bottom of the lake to serve as sustenance during the cold months.

Beavers are romantics at heart, or at least they’re monogamous. Dams are usually started by a young male looking for love or by a mated-for-life new couple. Beavers mate during the winter, from January to March. They have a gestation period of around 105 to 107 days. They give birth to one to four kits that weigh around 9-12 ounces. Beaver kits can swim 24 hours after birth and are usually weaned in around two weeks. At around two years of age, the kits leave the lodge and make one of their own. At three years, they find a monogamous mate.

A beaver’s oversized, leathery tail, which can grow up to 15 inches long and six inches wide, has uses both on land and in the water. While swimming, the beaver uses his tail as a rudder or as a siren by slapping it against the water to warn other beavers of a predator. On dry land, the tail acts as a prop to allow the beaver to sit upright or as a counterbalance so he doesn’t tip over while carrying heavy supplies in his teeth.

The American beaver typically weighs 30-60 pounds and are 23-39 inches long. The tail adds another 8-12 inches to their overall length.

The world’s largest beaver dam stretches 850 meters deep in the thick wilderness of northern Alberta and is visible from space. It was discovered after being spotted on satellite images in 2007, but scientists believe multiple generations of beavers have been working on the dam since the 1970s.

Enjoy Boundary County and all its wildlife!