Canada's national emblem, the beaver, is so much more than a face on our nickel. The castor canadensis is a 'keystone species' responsible for creating vital wetlands that support almost half of the species on Earth. In fact, 50% of North America’s threatened or endangered species rely on beaver wetlands for survival. They are also the only animals (other than humans) who are able to completely transform the landscape.
Beavers are hardworking, family-oriented animals who are often referred to as “nature’s engineers”. They live in monogamous pairs, with their kits (babies) and yearlings. Both adults take an active role in raising their young and as a group, they all live in a lodge.
While these 40-60 pound rodents may seem clumsy on land, they are fast and agile swimmers who can hold their breath for up to 20 minutes. They are truly built for aquatic environments, even possessing webbed hind feet, which contributes to their impressive swimming abilities. They also have valves in their ears and nose that close when swimming underwater. Amazingly, beavers also have a valve in their mouth behind the incisor teeth, which allows them to gnaw while underwater. Their tails are large and shaped like a canoe paddle. The tail can be likened to a boat rudder, steering the beaver as it swims, and offering them balance when on land, especially when carrying branches.
What ecosystem services do beavers offer?
Dam building can play a vital role in wetland maintenance and restoration, and sadly, so much of beaver activity is judged on too small a timescale. Specific benefits to wetlands include:
- Offering habitat to sensitive plant and animals: Beaver dams, as far back as the 1800s, were shown to be a nursery for juvenile salmon. They have been shown to offer ideal protected habitats for various frog and toad populations, and they are also credited with helping migrating songbirds. Dams stimulate the growth of species of plants that are critical food and habitat for songbirds in decline. The presence of beaver dams is associated with an increased diversity of songbird species.
- Improving water and soil quality: In addition to retaining silt (which assists with creating ideal farmland), beaver dams remove excess phosphates and nitrates (Which can cause eutrophication and contaminate drinking water) brought into the river system by farms. The cellulose-rich bottoms of the dam also metabolize pesticide and herbicides from agriculture. Scientists are now even confident that beaver dams may participate in denitrification (the conversion of nitrogen compounds back into nitrogen), a process with extreme environmental significance.
- Controlling water movement: Dams slow down the movement of water in flood waves that is often responsible for damage downstream. They also store water and increase flow during periods of little rain or drought.
So why are so many municipalities trapping and killing beaver families? Read on to find out.