Buddying Up with Beavers

By Paul Higginson, SPES Conservation Technician.

Coming to Canada from England, my knowledge of Canada’s national animal was minimal. I was aware only of phrases that personified people’s opinions about beavers – ‘beavering away’, ‘busy beaver’, ‘eager beaver’ and so on. Soon though, I became aware that they were not only an integral species for the structure of Canada’s wetlands but were a driving force throughout Canada’s historic fur-trade industry. Those days have passed, and the reasons for trapping beavers have become more ecological. 

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A busy beaver in Beaver Lake (Photo by Mark T White)

My first personal experience with beavers was to find a way to utilize their fascinating construction techniques, in order to mitigate their dams’ ability to prevent water flowing. The objective was to create a means to allow a continuous supply of water down into Stanley Park’s Beaver Creek for the benefit of plants and animals. The beaver’s insatiable dam-building fervor would create some interesting stumbling blocks however.

First and foremost we want to keep the beavers in Beaver Lake. Damming streams increases the surrounding water level and injects life-giving water into the surrounding areas, changing the ecosystem as more water remains throughout the year. This new ecosystem then accommodates hydrophytes (aquatic plants) – the beavers’ primary food source as well as creating habitat for waterfowl, amphibians, fish and aquatic invertebrates. Our challenge is how to maintain a water level that still allows human access to this recreational area.

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The beaver lodge in Beaver Lake (Photo by Steven Shen)

The second big issue is that beavers are capable of moving huge amounts of organic material. We removed a staggering 37.8 cubic meters of material from the outflow of Beaver Lake in just 6 years. This material, along with all the material gathered by the beavers, was from the native plants surrounding the lake. This steady removal of native plants can lead to the destabilization of riparian zones and the release of carbon back into the atmosphere.

Fortunately though, we now have various ways to allow beavers to make their dams in a monitored and non-detrimental way and in a way that promotes coexistence rather than an endless battle against them. We can protect specific trees (mostly younger ones and wildlife trees) by wrapping protective wire around their trunks. We have adapted their dams by installing what are called ‘beaver bafflers’ or ‘pond levelers’. Essentially, these systems subdue the sound of flowing water (which attracts beavers to build a dam) and promotes the consistent flow of water through perforated pipe systems which allow water to enter at a subsurface level and flow through the dams.

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A beaver baffler in Beaver Lake at the Beaver Creek outfall (Photo by SPES)

There are now four beaver bafflers in Stanley Park. The first was installed in June 2014 and guards the outflow of Beaver Lake, attempting to deter the beavers and reduce their desire to dam that area. They still continue regardless, as their home is a quick evening commute away. (At press time, the Park Board has decided to remove this baffler as it didn’t quite baffle the eager beavers; another solution will be sought.) Another baffler (2 pipes running through the dam) is at the head waters of Beaver Creek and a third quietly sits along Ceperley Creek, flowing into Lost Lagoon.

The beavers’ most recent damming expedition turned Ceperley Meadow into a mini wetland, creating numerous opportunities for increased biodiversity. It is a prime example of the beavers’ ability to change their surroundings (second only to humans). With the baffler in place at Ceperley Creek, we hope to mitigate flooding and coexist with beavers in a manner that benefits all.