The sound rose above the chirping of tree crickets as dusk descended along the shore of Twelve Mile Creek. I knew I was close; an animal I had been looking for in Short Hills Provincial Park for four years was nearby. In the darkness, I could barely see a dark shape swimming in the water. Another splash tail swipe, and it was gone. But it had confirmed my hopes: the beavers were back.
The Beaver (beaver canadensis) is North America’s largest rodent, rightly famous for its dam-building prowess, broad, flat tail, and environmental impact – and it’s found here in Niagara.
The beavers I searched for inhabited a meandering section of Twelve Mile Creek near Wetaskiwin Camp. I first encountered a couple grooming each other in the summer of 2015. Over the years I have captured many interesting moments and frolics with this family of beavers, and you can watch the best clips at bit.ly/2022beavers.
For more information on their behavior, I spoke with Michael Runtz, author of “Dam Builders: The Natural History of Beavers and their Ponds.” Runtz is a Carleton University professor, naturalist, photographer, and author of more than a dozen nature books. I first encountered Runtz’s vast knowledge of nature in Algonquin Park in the 1990s when he was leading an interpretive nature walk.
Beavers are one of the few animals capable of adapting the environment to their needs, instead of adapting to it. The trigger is sound: “Dam building turns out to be instinctual, triggered by the sound of rushing water,” Runtz said. This sound prompts beavers to build new dams or repair existing ones.
When the water above a beaver dam recedes, it creates a refuge for beavers to build a lodge and store food. Other animals and plants also benefit from the construction of the beaver.
“The biodiversity they create supports a myriad of plants and animals,” Runtz explained.
“For example, dragonflies prefer a still habitat, like a beaver pond. Damselflies, small animals and fish like bullheads do well in beaver ponds,” Runtz said. “They also provide habitat for many bird species such as herons and bitterns.
“There’s a pretty large web of life that thrives in a beaver pond.”
In 2019 I spotted a mated pair plus two kits in the same stretch of Twelve Mile Creek. Although they may not be the same, the odds are good – beavers mate for life.
“Beavers usually team up,” Runtz said, “until something happens to them.”
Runtz said beavers can live 20 years or more in captivity, but in the wild, “a 10-year-old beaver is an old beaver.”
I watched the whole family dine on a willow that had plunged into the stream. Beavers have ever-growing incisors and iron-hardened enamel. This allows them to chew through trees with ample time – and the ability to easily remove bark and twigs.
Beavers breed in winter and give birth in late spring. Newborns stay in the box; when they are older, they leave the lodge to eat and play. A kit even helped collect food by carrying choice branches from the tree to the lodge.
Beavers are herbivores and their diet is quite varied, Runtz said.
“In summer, fresh growth, herbaceous shrubs and wild flowers, yellow water lily, bulrush and water lilies. In autumn and winter mainly woody material, bark and twigs.
In southern Ontario, beavers are not very afraid of predators. Runtz said the fisherman (Pekania pennanti) and Great Horned Owl (Bubo virginianus) can feed on beavers and red foxes (Vulpes vulpes) can be opportunistic predators on young shoreline kittens. In Algonquin Park, Eastern Wolves (Canis lupus wild dog) are also known to attack adults.
The animals that beavers most often come into conflict with are humans. Due to their instinctive habit of damming anything that produces the sound of running water, beavers often inadvertently clog culverts or water intakes, and water backed up by a dam can cause flooding upstream. .
One solution to flooding is the beaver baffle, Runtz said.
“Beaver baffles are pipes that cross a dam and emerge upstream and control the water level above a certain height. The beavers may stay, but the water from the dams upstream will not continuously rise and create larger floods.
Beavers can be seen in many places in the region, and they’re not particularly shy, Runtz said.
“In my experience, beavers are quite tolerant of human presence. There are beavers in Toronto. They tolerate people quite well. It’s the opposite. Human tolerance to beavers is quite low.
“Dam Builders” provides more information and photographs on these incredible rodents. Young naturalists might also be interested in Runtz’s co-authored book “At Home with the Beaver.” Both can be found at nature bookstores.