Beavers: Ecosystem Engineers

April 6, 2021

Photo: Niklas Hamann

Weighing in anywhere between 35 and 50 pounds, beavers are North America’s largest rodent. In the 1800s, beaver fur was a valuable trade item that nearly drove the species to extinction.

Thanks to restocking efforts in the early 1900s, beaver populations have fully recovered, and many landowners across the Triangle have been impacted by their presence. Some landowners might not realize that beavers are valuable to humans for reasons other than their pelts. Recent studies have shown that North America’s largest rodent has a positive impact on water quality.

Similar to us, beavers are experts at manipulating their environments to create what they need. Beavers make their own habitat by constructing dams on flowing water to establish deep ponds in which they can swim. Within these ponds, beavers construct lodges, where they live and safeguard their young. The pond itself provides protection to the beaver colony from predators such as coyote, bear, etc.

While the beavers’ motives might be selfish, the wetlands they form ultimately help humans. Pollutants from cities and agricultural fields are washed overground by rainfall until they reach water bodies. If those pollutants reach a wetland, the velocity of flow is reduced and pollution particles have time to settle onto the bottom of the wetland, where they might bind to soil or be taken up by plants.

As much as 90% of sediments in runoff could be removed if water passes through a wetland. Compare that to a situation where a wetland isn’t present and those pollutants flow straight into Jordan Lake or Falls Lake, which are major sources of drinking water for the Triangle. Not only is drinking water compromised, but all of the species that depend on those water sources could be harmed by pollutants from many miles away.

The US Department of the Interior published a study in 1996 that showed North Carolina’s wetlands have decreased from 11 million acres at the time of colonization to 5.7 million acres. As the Triangle’s population continues to grow, wetlands provide a solution to mitigate negative effects of development such as increased water pollution. Some cities are building their own wetlands to help with pollution, but beavers provide wetland construction free of charge.

As long as beavers don’t interfere with landowners’ use of the property, they provide many benefits to people and wildlife; however, beaver ponds might not be ideal in residential areas or if they’re interfering with agriculture or silviculture. For this reason, beavers can become a nuisance for some landowners.

The traditional solution for beaver management has involved trapping and removal of all beavers in an area. While trapping is sometimes necessary to protect property, a study performed by the Humane Society in 2006 showed that trapping as a management solution has a 79% failure rate within two years due to resettlement by new beavers.

Alternative management options include coexisting with beavers by managing their ponds to not interfere with conflicting land use.

Triangle Land Conservancy’s stewardship team has been challenged for years by the large beaver dam at Brumley Nature Preserve. The dam continued to flood our trail system and cause problems for people enjoying the preserve. Because TLC understands the beavers’ positive impact on water quality and the ecosystem, we decided to re-route our trails and coexist alongside the beavers. To do this, we needed to make sure that the beaver pond wouldn’t continually grow and flood more of the preserve.

Last summer, we installed what we call a “beaver deceiver,” otherwise known as a pond leveler or a flow device. The beaver deceiver was constructed using a PVC pipe to create a permanent leak in the dam that the beavers cannot stop. One end of the pipe has several drilled holes and then is surrounded with wire so that beavers can’t dam the flow.

The beaver deceiver has worked very well for TLC and similar flow devices were satisfactory for 93% of Massachusetts landowners in a 2006 study performed by Tufts University. Additionally, a study by the Virginia Department of Transportation found that for every one dollar spent on flow device installation, eight dollars was saved in future road repairs, maintenance, and beaver population control activities.

Beavers are undoubtedly impressive animals, but living or operating near a beaver dam can be difficult. Understanding beavers’ importance to the environment is important when deciding on a management plan.

For more information about TLC’s beaver deceiver or its installation, please contact Caroline Durham at [email protected]. For more information on beaver management, visit ncwildlife.org/beaver.

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