More Nature Notes
Beavers are the largest rodents in North America and the second largest in the world, weighing in at up to 32 kg. On land beavers appear somewhat ungainly, but in the water it’s a different story. They are strong graceful swimmers, both on the surface and under water, and can attain speeds of up to 7 km per hour if alarmed. They are well-adapted to their aquatic habitat and their endless activities in construction engineering. Beavers are able to see clearly under water, thanks to a specialized transparent membrane that's drawn over the eyes when diving. Both nostrils and ears can be closed under water. The front paws have sharp claws and function very much like hands for carrying and working with building materials. The rear paws are larger with blunt claws and are fully-webbed for swimming. The beaver’s flat leathery and muscular tail acts as a four-way rudder for swimming, and as a prop and counter-balance when sitting upright on land and carrying branches and stones. Beavers have exceptionally strong teeth, especially the upper and lower incisors, with which they can gnaw through and fell large trees. The fur is very dense and gets continuously recoated with oil during grooming to maintain water repellence.
Beavers are wonderful builders and what they build depends on where they live. Dams, their best-known structure, are built to ensure that underwater habitat will be open to them in winter, by creating a pond deep enough that it will not freeze to the bottom. Dams are maintained on a daily basis throughout the year. Deep water provides storage places for winter food and a year-round underwater access to the lodge or den. Lodges, containing nesting and living quarters, are built on the shore or in the water, and always have underwater entrances secure from predators. Another impressive feat of beavers is the building of canals, which may extend several hundred metres along the base of a wooded hillside, and are used to provide easy transportation of their woody food supplies.
Beavers mate for life and produce litters of 3-4 young every May or June. New-born kits are already well-furred, have teeth, and can see, walk and swim, though they usually remain in the den for at least a month. Juvenile beavers stay with their parents for 2-3 years, before dispersing along streams or even across country to find mates and establish their own homes and families.
Beavers are found throughout Canada and are very much evident in the Don watershed, including the upper West Don. You can probably see evidence of their activity in the BSG. Unfortunately they have a habit of felling some of the trees planted so carefully by local residents a few years earlier, to provide materials for their dams and lodges.