By Natalie Sopinka
At the September monthly meeting OFNC members were treated to an enlightening and entertaining presentation on Canada’s national animal, the beaver. Showcased on The Hudson’s Bay Company’s coat of arms and Parks Canada’s logo, and the first animal to be featured on a postage stamp, the beaver is a well-recognized emblem of Canadian culture and history. The beaver is also the topic covered in a new book by naturalist, OFNC member of 40+ years, and Carleton University Instructor Michael Runtz – Dam Builders: The Natural History of Beavers and their Ponds. Through photographs and stories, Mike shared many fascinating aspects of beaver natural history.
Here in Canada resides the North American beaver (Castor canadensis). Their orange teeth are iron rich and tough enough to chew through trees. This is a good thing because beavers are quite fond of trees – different kinds (e.g., willow, alder, birch, poplar) and their different components (branches, twigs, leaves, bark). Wood (primarily bark) not only forms a major part of the beaver’s diet (along with terrestrial and aquatic plants including water-lilies) but is also used as building material for their structures.
Construction usually starts with the building of a dam, which results in a pond. Next, a lodge is built. Beavers are especially industrious during the autumn, ensuring their lodges are well insulated with mud that helps keep them warm during the cold winter months. In addition, near the lodge they create a food cache, of which the top portion is often adorned with less edible sticks that get frozen in the ice while the edible branches placed on the bottom remain accessible all winter.
Whether it’s grooming between mom and kits, territorial disputes among rival males or aggressive tail slapping to deter a predator, beavers are social creatures and lodges house family groups spanning three generations.
A keystone species
A beaver dam dramatically changes its surrounding environment, in the process benefiting numerous flora and fauna. The formation of a beaver pond is coupled with growth of aquatic vegetation rich in sodium, which moose consume to fulfill dietary needs. Dead trees provide fodder for beetles, nest sites for Northern Flickers, and supports for the assembly of spiderwebs. Fallen trees provide basking spots for painted turtles and grooming platforms for ducks. Fish seek shelter in the submerged food caches, and breeding amphibians use ponds as nurseries for young tadpoles.
When a dam breaks, the beaver pond transforms into a meadow, a thriving ecosystem full of grasses, sedges and wildflowers that attract myriad pollinators and grazing bears. Meadow voles scurry about, providing sustenance for foxes, hawks, owls, snakes and weasels. Moose sometimes mate in beaver meadows and wolf pups play in the meadows while their parents hunt. Eventually forest growth engulfs a meadow, making the habitat suitable once again for the return of beavers and their ponds.
The human connection
The natural history of beavers is also intertwined with the lives of humans. Mike likened beaver ponds to living art galleries. For naturalists, photographers, educators, and families exploring beaver ponds is a year-round adventure. Next time you find yourself saying “I’m bored,” head outdoors and stop by your local beaver pond.