The largest beaver dam on record was 775 metres long, located in Wood Buffalo National Park, Alta. (Photo: Derek Otway/Unsplash)

It starts with the sound of running water. There’s something in a beaver’s rodent brain that draws it to the sound, compelling it to build. To dam. To slow the flow. To hold that water in its little chunk of landscape a little longer. The beaver is following its instincts to build a home, with easy access to tasty morsels to gnaw on: aspen, willow, birch, maple. But it’s doing something more. It’s creating a more resilient watershed.

During the 1940s, a bizarre project saw beavers parachuted into Baugh Creek, Idaho, because they were seen as a nuisance in cities and towns. The beavers did what they do best and created a lush mosaic of ecosystems.

Seven decades later, in 2018, a wildfire swept through Baugh Creek. Satellite imagery showed a remarkable picture: that beaver-engineered, verdant valley appeared unscathed amid the wildfire-charred hills.

Researchers have found that beavers contribute more to keeping water in the landscape than climate, precipitation and temperature combined. As beaver dams slow water down, backing it up into ponds, this not only creates habitat for a biodiverse ecosystem but better protects the landscape from increasing droughts and fires that accompany warming temperatures associated with climate change.

Beaver dams also filter the water, which removes contaminants and moderates water temperature. When deeper beaver ponds “stratify,” separating into layers, they create cool refugia for various fish species, which can attract protein-loving predators to beaver ponds. The nutrient-rich sediment and still water also cultivate plants for grazing herbivores. Ponds eventually give way to lush meadows as, once the beavers’ journey to trees becomes too far, beavers abandon their dams to begin all over again somewhere else.

The resulting landscape is a patchwork of meadows and wetlands — with a range of ages and successional stages — that become more diverse as beavers repeatedly colonize and abandon their dam sites. With droughts, wildfires and flooding predicted to increase in Canadian landscapes, perhaps we can let beavers do what they do best: create resilient watersheds for the future.

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