On February 22, 2022, Skip Lisle (Masters in Wildlife Management) of Vermont-based Beaver Deceivers shared his experience working to address human-beaver conflicts that arise when beavers plug culverts or build dams that cause roads or human-occupied land to flood. You can access a video of his talk at the end of this post.
Skip started with a bit of history. In the U.S., we altered or filled vast acreage of wetlands for centuries, only to realize that they have tremendous value – ecologically and economically. Ecologically, wetlands support countless species – insects, birds, fish, plants, and game animals. They support incredible biodiversity, provide flood control during intense storms, remove sediment and purify water, not to mention the color, beauty, and rich soundscape they offer.
To rectify past wrongs, we’re now ‘building’ wetlands, at tremendous cost, often millions of dollars. And yet, there is an animal that will build wetlands…for free! Pre-settlement, there were countless beaver ‘flowages’ (a term used to describe areas flooded by beaver dams) along rivers and streams, creating rich floodplains that supported countless plants and animals.
These flowages probably occupied 1.5 – 3% of the landscape. Starting around the 1600s, the fur trade practically eliminated beavers from the landscape and as beavers disappeared, their dams deteriorated and those rich floodplains reverted to forestland or farm fields.
For decades, beavers have been returning to the same areas they once occupied, attracted by their basic structure – places where they can create the biggest pond with the least effort. Many farm fields with streams running through them were likely once beaver habitat – their rich soil creating by thousands of years (post-ice age) of sediment collecting in broad floodplains.
As beavers returned, conflicts with humans arose. Beavers are attracted by the sound and movement of fast flowing water. Roads with culverts are beaver magnets. To a beaver, that road is essentially a ready-made ‘dam’ with one small hole that needs to be plugged. Big payoff for minimal effort.
Skip pointed out that killing or removing beavers from these locations is not a permanent solution. It’s inhumane to the beaver and it doesn’t solve the problem. The location will remain very attractive to other beavers, for the same reasons it attracted the first one.
That’s where Skip and his trademarked Beaver Deceiver™ come in. So-called ‘flow control devices’ prevent beavers from plugging culverts by blocking their access to the culvert and removing the sound and action of fast-moving water from the culvert site. This is accomplished by building sturdy, rust-resistant porous boxes around culvert entrances, often accompanied by long pipes moving the water intake point away from the culvert mouth and underwater while protecting the pipe mouth from the beaver.
Skip sometimes puts decks on top of his Beaver Deceivers™ so they can be used for other practical purposes, such as accessing pond water by firefighters or ‘calling in moose’ during hunting season.
It takes years of experience to learn how to outsmart beavers. Every site is different and requires a site-specific solution. Skip maintains that beavers aren’t that smart, they’re just responding – based on years of evolution – to particular stimuli (the sound and feel of moving water).
Nevertheless, beavers are INCREDIBLY persistent and hardworking, as anyone can attest who has removed DAILY masses of branches, fern root masses, large stones, and mud placed by a beaver trying to dam a site. Suffice to say that the beavers are not deterred by the daily removal.
Skip shared photos of several Beaver Dam Analogs (BDAs) or as he calls them, ‘starter beaver dams.’ Apparently, it’s not hard to get a beaver to build a dam in a location of your choosing, if you know what you’re doing. This is sometimes used as a strategy to keep them away from ‘conflict points’ ( places where you don’t want them to build a dam).
Skip noted that many beaver habitats are permanent. While some beavers will move up and down a stream corridor depending on the availability of food, in a large beaver flowage, there is plenty of food to support them. Beavers love soft vegetation – water lilies, cattails – essentially many of the plants that grow in a large wetland system. Poplar and aspen are their favorite trees – for their tender leaves. They will fell a poplar just to eat the leaves. In the winter, they eat branches and bark, which they stockpile in a food cache in and near their lodge.
So, we have the technology to co-exist with beavers. Flow control devices can be designed to maintain the water level in a beaver flowage so that it doesn’t conflict with roads, agriculture, and other uses of land. By using these devices, we can prevent future conflicts and keep beavers and the incredible habitat they create in our landscapes. These devices also save taxpayer money that goes into annual culvert maintenance (labor and heavy equipment needed to clear beaver-clogged culverts), flood control, and much more.
Plus, beavers create unparalleled habitat for plants and animals. Skip shared pictures of multiple bird species using a single beaver lodge as a perch, including a Canada goose that made her nest atop it! And don’t forget the joy we get from experiencing the brilliant color and sound landscapes of beaver flowages. These areas literally teem with life!
We don’t need to spend tens of thousands of dollars creating man-made wetlands. Let beavers do the work!
We hope everyone will share this information with friends, family, town leaders, road crews, Inland Fisheries and Wildlife, Department of Transportation and beyond. Let them know that: 1) we want beavers on our landscape and 2) management tools exist that enable the tenacity and work ethic of beavers to be harnessed and used as a force for good.
For more information about the history of beavers on the North American landscape, read the wonderful book Eager: The Surprising Secret Life of Beavers and Why They Matter, by Ben Goldfarb. There’s a whole chapter on Skip Lisle in it. You can find it online here or at your local bookstore.
You can watch an interview with Skip that includes beautiful video footage of the beaver flowage on his property and some pretty good-looking beavers. There is lots of info on his website, including case studies documenting the cost savings over time of Beaver Deceivers™ vs. annual maintenance.
You can find lots of information about beaver biology, habits, and habitat from the Smithsonian Zoo here.