Beavers are the largest native rodents found in North America. Adults average 35 pounds with some individuals reaching as much as 65 pounds. Specimens of 90 pounds have also been recorded.
Beavers can reach four to five feet in length from nose to the tip of their tail. Even more amazing is that prehistoric beavers were almost as large as modern-day bears. Can you imagine the dams and lodges animals of that size would construct, if in fact they shared similar behaviors as modern beavers? One can easily imagine lakes, not ponds, being created by such creatures.
Long-lived for rodents, beavers can reach 20 years of age. They tend to form pair bonds for life. Newborn beavers, or kits as they’re called, remain with their parents for two years until they disperse to locate their own mates and territories. One litter per year of two to four kits is born to a mated pair.
So many marvelous adaptations help to make beavers perfectly suited to an aquatic lifestyle: powerful hind legs with flipper-like webbed feet propel beavers through the water; nostrils close at will to keep water out; clawed toes help with digging and gripping sticks; their dense, oily fur repels water and keeps them warm in frigid conditions; massive chisel-like incisors cut through wood; and their unusual tail is used as both a rudder for swimming and as support when standing. And about that tail, which is often heard, but not necessarily seen, is also used as a warning signal. A loud slap on the surface of the water warns other beavers in the pond that danger lurks nearby.
Aside from the impressive dams that beavers construct to contain water that they require to survive, the lodges of beavers are unique and elaborate in design, too. The inside chamber may be as wide as eight feet and as high as three feet and is lined with soft vegetative materials like grass and woodchips. Depending also on the structure’s design, the entrances may differ as well. Some are straight up and through the floor of the lodge, whereas other lodges are entered through gradually sloped entrance holes.
Lodges are amazing structures in their own right. While many species of wildlife the world over build shelters, I cannot think of another creature capable of building as durable a shelter as a beaver lodge. Using mud from the bottom of a pond, lake, or river, beavers literally excavate the material up to the location where the lodge is built — usually along the edge of the pond and land. Reinforced with sticks, the lodge soon becomes nearly impenetrable to the weather and predators. Lodges are even equipped with an air vent. Indeed, beavers think of everything.
Over the years I’ve taken time to examine many a beaver lodge and dam. Accessed from either land or water, it’s fascinating to walk on top of lodges or on dams. Some of the lodges and dams that I’ve observed closely were massive and extensive. One such lodge and dam, located in Kittson County on a state wildlife management area, is the most impressive of all. The lodge is as large as a truck, and the dam is over a quarter-mile long. Built and maintained by generations of beavers, these structures are living testament to the fortitude of this remarkable animal.
Beavers are especially active in the fall as they prepare for winter. Branches from felled trees are carried in their mouths as they swim near their lodges where the branches are then cached underwater. Called food rafts, beavers cache these food items underwater for consuming throughout the winter months. Whenever a meal is needed, the beaver simply exits its lodge, swims below the ice to the food raft, and carries back with them something to eat inside the warm and cozy lodge.
Though sometimes viewed as pests because of the problems they can create for people, property, and roadways as a result of damming activities that back up water and cause flooding, beaver ponds also provide many benefits for other species of wildlife. Flooded trees often die and subsequently become excellent nesting trees for wood ducks and other cavity-using wildlife. River otter, mink, turtles, frogs, toads, salamanders, aquatic invertebrates, fish, and many species of birds such as belted kingfishers, great blue herons, and scores of songbirds, shorebirds, and waterfowl use beaver ponds and the associated habitats. In time, because of sedimentation, diminishing timber, or hydrologic changes, beavers eventually abandon their ponds. These old ponds often become lush meadows.
How and why these amazing animals behave is one of the many mysteries in the animal kingdom. Researchers believe it’s the sound of running water that compels beavers to construct their dams. Regardless of how and why they do what they do, beavers, with their astonishing engineering feats and the benefits to wildlife they provide, are here to observe and appreciate as we get out and enjoy the great outdoors.