Beaver
The beaver is one of the most recognizable animals in Canada, as our national animal and appearing on our five-cent coin. Beavers are truly magnificent creatures and are well deserving of this honour. Beavers are prominent animals in the stories of many Indigenous peoples of Canada. They have different symbolism in various tribes’ stories, from hardworking and wise, to stubborn and inconsiderate.
Description
The North American beaver (Castor canadensis) is the world’s second largest rodent. Because beavers live partially in water, they are adapted for swimming. Their fur is thick, oily and waterproof. Beavers use their webbed feet to propel themselves and their large flat tail acts like a rudder. They also use their tail to signal danger by slapping it on the water surface. Beavers close their ears and nostrils in the water and have special transparent eyelids to protect their eyes when swimming. Like all rodents, their long, sharp, front teeth constantly grow.
Habitat
Beavers live in all Canadian provinces, much of the U.S.A. and into northern Mexico. The primary habitat of beavers is in and near rivers, ponds and lakes. They can also inhabit river estuary intertidal zones. Beavers are mainly nocturnal, meaning they are most active at night.
Beavers build their dams and lodges in flowing waters. They use their teeth to cut down trees in surrounding areas and bring them back to the river. Beavers dam waters to deepen or widen a stream or pond, allowing them to then build a lodge surrounded by water, like a moat around a castle. The beaver is actually able to change its environment by building dams. Dams create a new habitat in the river and around the banks for other organisms. Damming a water body keeps nutrients and food close to the lodge for easy access; dams will hold back water, but will also filter out the suspended soils in the water. This helps get rid of pollutants in the water, but also helps retain a large majority of the nutrients. Although beavers are considered to be helpful in this way to the envornment, they are also considered a nuisance because their dams can cause flooding.
Lodges are separate from dams both structurally and functionally. While a dam’s role is to block the water from flowing, a lodge is the place where the beaver lives. Lodges all follow the same basic design. There is a platform of sticks and other materials, and there is a suspended arch over top made of sticks, mud and grass. Beavers move in and out of their lodge underwater through submerged tunnels, and therefore the dams protect them against predators that live on the land. The inside of the lodge is above the water level, so they have a warm, safe and fairly dry, place to sleep, live and raise their young. In the winter they eat inside their lodge, whereas in the summer they mostly eat foods nearby. Beavers will begin building a lodge or repair their existing lodge, in August. By the time the winter rolls around, the mud in the arch will freeze, making it impossible for predators to enter the lodge and protecting the beavers all winter. Adult beavers will primarily live in their lodge during the winter and when the ice melts, they will roam around the pond until autumn. Beavers often go back to the same lodge each year.
Life Cycle
Beavers are monogamous, meaning they mate for life. Each year they mate early in the winter and produce a litter of four to five kits in the early spring. These juveniles will stay in the lodge for the first month. The mother will act as the primary caregiver of the kits while the father defends the territory around the lodge. After a year or so, juveniles begin to hunt and will follow the parents outside the lodge. At two years of age, the older kits begin to take care of the younger siblings. Beavers reach sexual maturity by age three.
If the beavers are not threatened by food shortage, habitat availability or population density, the newly mature beaver ventures out on its own, settling down in a stream or pond not too far away from where it was born.
Diet
In the summer, beavers rely on a diet of cattails, water lilies, and other aquatic vegetation. They do not eat fish, contrary to popular belief. In the winter, when there are few other foods, beavers eat the underbark of wood that they have stored in their lodge.
Biomimicry
Many aquatic mammals have thick layers of fat to keep them warm in the water. Beavers do not have the blubber layer that whales and seals have, but instead beavers have fur, and the individual hairs trap air as they move frequently between water and land. The air insulates the beavers from the cold water, allowing them to stay warm.
Researchers and entrepreneurs are already attempting to imitate this method of insulation in wetsuits. The wetsuits are meant to be used mostly by surfers who, like beavers, go back and forth between the air and water frequently. (http://news.mit.edu/2016/beaver-inspired-wetsuits-surfers-1005)
Interesting Facts:
- Beavers are closely related to gophers.
- Beavers can stay underwater for 15 minutes.
- As a beaver’s teeth continuously grow, they are not dulled by cutting trees.
- Giant beavers, the largest known rodent and now extinct, were probably distant relatives of today’s beavers. Fossils of these animals have been found all across North America, but particularly along the Atlantic coast, Ontario and the Yukon.
https://www.beringia.com/exhibit/ice-age-animals/giant-beaver
Ryan Small
