Busy Beavers: How One Small Creature Makes A Big Splash In Wetland Ecosystems

2021-07-12

 |  Biodiversity/Conservation

Despite being one of Canada’s most iconic animals, the North American beaver (castor canadensis) has got a bad rap. Traditionally seen as pests that flood farmlands, destroy public infrastructure, and fall trees (Campbell, 2017; BBC, 2021; Samson, 2017, Global News, 2014); beavers play a critical role in supporting wetlands across Canada and the US. Through their services, beavers punch far above their weight in the positive impact they have on the ecosystems they call home. As we begin to understand more about this infamous rodent, the need for beaver conservation in Canada becomes clearer. 

Beavers offer a long list of ecological services wherever they roam. By building dams, beavers alter the flow of streams and create beaver ponds. Through their ingenious (and sometimes relentless) engineering, beavers help make more resilient ecosystems. Beaver dams decrease the risk of erosion and flooding by reducing the velocity of river streams (Rosell et al., 2005). Beavers also increase storage capacity of rivers of up to 30% of water in catchments (Rosell et al., 2005). This water storage allows for a continuous flow of water from upstream areas to downstream during periods of droughts, and positively improves the resiliency and survival of the overall ecosystem (Rosell et al., 2005). 

Beaver dams not only create more drought-hardy wetlands, but also provide habitats to a variety of flora and fauna, including fish, birds, mammals, amphibians and insects (Parks Canada, 2019). As Ben Goldfarb describes in “Eager: The Surprising Secret Life of Beavers”, beavers are integral in fostering plant and animal diversity in the rivers they live in, creating more complex and healthier ecosystems (2018, 55). Aquatic insects shelter in beaver dams, beaver ponds provide grassy fringes for ducks to nest in, and songbirds nest in beaver-cut willows (Goldfarb, 2018, 55). Turtles, otters and lizards are often linked to the presence of beavers in river settings because of the favourable conditions that beavers create (Goldfarb, 2018, 57). Otters often gravitate towards areas that are already populated by beavers (Peterson and Schulte 2016, 38). Therefore, the protection of beavers can support the recovery of river otter populations in Canada and the US (Peterson and Schulte 2016, 38). Smaller creatures like wood frogs also use beaver tunnels to swim up and reach forest feeding areas without being detected by predators (Goldfarb, 2018, 56). In terms of plants, “beavers have been known to increase plant species in streamside areas by more than a third” in upstate New York and Southern Ontario (Goldfarb, 2018, 55). Despite having a reputation for being bad for salmon populations, beavers have positively impacted salmon populations in Canada. Salmon use beaver ponds as breeding grounds in the summers and benefit from the increase in invertebrate supply that beavers bring (Goldfarb, 2018, 110). While beaver dams can be an obstacle for migrating salmon, most fish are able to pass through dams by swimming underneath or jumping (Goldfarb, 2018, 110). 

In addition to habitat creation, beavers positively impact water biochemistry. Beaver ponds act like sediment traps, storing large amounts of carbon, nitrogen and phosphorus in the sediment (Hill and Duval, 2009; Peterson and Schulte, 2016). Storing nutrients in the sediment helps improve the overall water quality by increasing nutrient retention (Hill and Duval, 2009). By reducing the rate of water flow, beaver dams decrease decay rates of organic matter in pond and stream sediment, which allows for a reduction in the total organic carbon released by the pond (Rosell et al., 2005). 

Despite the clear benefits they provide to the ecosystems they create, beavers continue to be targeted for removal. Even after the beaver’s miraculous recovery from near extinction in the early 1900’s (Gibson and Olden, 2014), municipalities across Canada continue to see beavers as pesky rodents that need to be removed from both our urban and rural landscapes (BBC, 2021). Beaver dams that are found on both private and public property are often destroyed due to a misunderstanding of the role of the dam in the river ecosystem or fear of flooding. However, devices such as the beaver deceiver (an underwater fence that protects culverts from being obstructed from beaver’s dams) can mitigate the potential negative effects of beavers on private property, while also posing no threat to the beavers (Government of Canada, 2014). 

In addition to facing backlash from local property owners and municipalities, beavers face major threats from habitat loss and pollution. Deforestation in Canada’s boreal forests is causing a loss of beaver habitats (Stoll and Westbrook, 2020). Climate change has further caused beaver-inhabited wetlands to experience a reduction in the carrying capacity of beavers due to increased cases of extreme drought and changes to vegetation and will continue to pose increasing threats to the survival of beavers and the wetland creatures that depend on beavers (Hood and Bayley, 2008). Morever, due to an increase in mining activities near and around major beaver sites, pollutants like cadmium are being introduced into beaver populations at alarming rates (Peterson and Schulte, 2016). Cadmium not only negatively impacts beaver populations, but also creates trickle down effects for the rest of the ecosystem. A reduction in the beaver population means a reduction in the important ecological services that beavers provide. Furthermore, since beaver ponds provide habitats for salmonid fishes, beavers may pass the heavy metal toxins onto otters or humans through the fish that breed in their ponds (Peterson and Schulte, 2016). 

Advocating for the conservation of beaver populations in Canada promotes the continued health of the overall ecosystems they live in. Beaver conservation in Canada requires an ongoing effort to protect the lands and waters they live in. Youth in Canada can contribute to beaver conservation by advocating for the use of beaver-friendly devices in their municipality’s wildlife management, the conservation of Canada’s wetlands, and climate change mitigation. While no one species alone can save an ecosystem, beavers are possibly our best chance of conserving wetlands for generations to come. 

APA Citations

BBC News. (2021, 26 Apr). Canadian beavers chomp down town’s internet.

https://www.bbc.com/news/world-us-canada-56894828

Campbell, M. (2017). Canada’s beaver problem. Macleans. https://www.macleans.ca/news/canada/canadas-beaver-problem/ 

Global News. (2014, Jul 29). P.E.I. beaver blamed for felling tree that damaged couple’s car. https://globalnews.ca/news/1479478/p-e-i-beaver-blamed-for-felling-tree-that-damaged-couples-car/

Goldfarb, B. (2018). “Eager: The Surprising, Secret Life of Beavers and Why They Matter.” Chelsea Green Publishing: White River Junction, VT. 

Ecology, management and conservation implications of North American beaver (castor canadensis) in dryland streams, Olden and Gibson, 2014

https://onlinelibrary-wiley-com.proxy.queensu.ca/doi/epdf/10.1002/aqc.2432

Government of Canada. (2014). Beaver Control Program to Reduce Damage to Agricultural Land.

https://www.canada.ca/en/news/archive/2014/05/beaver-control-program-reduce-damage-agricultural-land.html

Hill, A.R. and Duval, T.P. (2009). Beaver dams along an agricultural stream in southern Ontario, Canada: their impact on riparian zone hydrology and nitrogen chemistry. Hydrological Processes 23(9), pp. 1324-1336. 

https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.7249?casa_token=OPxENQhay_AAAAAA:BEH7Tr3gALPmE-vkepuojHXY2oZRC1OawMY06gvVssfFrOE-Akf8y8VTkFY9Cjpx4HSdMQMPgCIpl68

Hood, G.A. and Bayley, S.E. (2008). “Beaver (Castor canadensis) mitigate the effects of climate on the area of open water in boreal wetlands in western Canada.” Biological Conservation 141, pp. 556-567. http://www.pacificwolves.org/wp-content/uploads/2019/06/Hood-and-Bayley_2008.pdf 

Olden, J.D., and Gibson, P.P. (2014). Ecology, management and conservation implications of North American beaver (castor canadensis) in dryland streams. Aquatic Conservation: Marine and Freshwater Ecosystems 24(3), pp. 391-409. 

https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.2432

Parks Canada. (2019). Beavers: 5 Ways Beavers Keep Our Ecosystems Healthy.

https://www.pc.gc.ca/en/pn-np/mb/riding/nature/animals/mammals/castors-beavers

Peterson E.K., Schulte, B.A. (2016). Impacts of Pollutants on Beavers and Otters with Implications for Ecosystem Ramifications. Journal of Contemporary Water Research & Education, 157(1), pp. 33-45. 

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1936-704X.2016.03212.x

Rosell, F., Bozsér, O., Collen, P., and Parker, H. (2005). Ecological Impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems. Mammal Rev., 35(4), pp. 248–276. 

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2907.2005.00067.x?casa_token=Wz5UCABSglMAAAAA%3A8txh-b_QYsiq6bpyS8KDwGqlcUqoTZodS6wmmRphBlsMe3zK0FV07mhoUyWz4LlmEBQabi0QgXMBIoU

Samson, S. (2017, Aug 7). Homeowners and industry struggling with beaver dam flooding. CBC News. https://www.cbc.ca/news/canada/sudbury/nuisance-beavers-northern-ontario-1.4235660

Stoll, N.L. and Westbrook, C.J. (2020). Beaver dam capacity of Canada’s boreal plain in response to environmental change. Scientific Reports, 10(16800). 

https://www.nature.com/articles/s41598-020-73095-z