By Ken Bevis, stewardship wildlife biologist, Washington State Department of Natural Resources, email@example.com
We all have to believe in something, and I’m a Beaver Believer!
We are a dedicated, sometimes fanatical, informal cadre devoted to the importance of beavers on the landscape. No, there aren’t any dues or meetings, no uniforms, just working toward a shift in attitude towards this furry, flat-tailed, buck-toothed, often misunderstood and under-appreciated, charismatic, ecological giant. Let me explain …
Summer is dry. Hot. Getting more so. This makes it tough to be an animal, fish, or plant – or for that matter, any living organism!
Water falls regularly from the sky, right? But not always at a steady, reliable pace, and it soaks into the ground, coming back out slowly and filling our streams, which run off to the sea. How can we slow this process, especially in dry environments, so that more water is available longer? One way is with small catchments on streams that raise the water table in surrounding areas, charge groundwater reserves, and provide rich habitats for many species. We can build them at great expense and effort, or …
What if there was an animal that built perfect catchment structures out of local materials, at no cost to people? And who did it continuously and in perpetuity? Creating these catchment structures, raising the water table thus keeping areas moist in drought, and creating habitats to help plants, fish, and animals survive?
Such a critter exists. Meet the beaver, Castor canadensis!
Beavers are the largest rodent in North America, and live in a wide variety of habitats across most of Canada and the United States. All they need is water, food, and limited persecution. They are highly social and live in small colonies, usually consisting of four to 10 animals, with of a breeding pair and offspring of the previous two years, all working together to maintain dams or bank dens. Unlike other rodents who are prolific breeders with limited rearing of the young, beavers only breed once per year and invest heavily in the training and survival of their offspring. They are amiable animals, too.
Washington Department of Fish and Wildlife biologist William Meyer, who helped found the Yakima Basin beaver relocation project, said about beavers, “I always describe them as ‘civil’ and easygoing (not always with each other, but toward us). When we handled them, they were always incredibly gentle and easy-rolling.”
Beavers were very important in the European settlement of North America. They were trapped extensively for their lush pelts, which served as a type of currency for many years. And then there was the beaver hat craze in the 19th century, when their fine underfur was felted into the dapper top hats we see in classic imagery.
Their fantastic fur, with 126,000 hairs per square inch, almost led to their downfall. They were already trapped out of eastern North America by the early 1700s, and the 19th-century fur rush in the Western U.S. almost led to extirpation here as well. We are now learning that this removal has had some wide-reaching ecological effects (Goldfarb 2018).
Beavers’ effects on overall hydrology can provide a profound benefit to streams, as the water stored behind their dams recharges groundwater, as well as creating those rich, still water habitats. This can provide longer-lasting stream base flows and trap sediments. In addition, unexpectedly, beavers actually lower stream temperatures because of the effect of water being moved out into the water table, and slowly seeping back into the streams.
Don’t the dams block fish migrations? It is now widely believed that beaver dams are not a significant impediment to fish, i.e. salmon, as the small ones manage to migrate through the cracks and leaks in the dams, (as shown by rearing juveniles above dams in ponds) and in many cases, migrating adult salmon are able to jump dams because many migrations occur at high water. There is even a bumper sticker, “Beaver Taught Salmon to Jump.” Any dam systems that actually are barriers can wind up being temporary, as flood flows will often blow out the structures.
For a great view of the ecological, hydrological and habitat benefits from beavers, read this excellent book on the topic: “Eager: The Surprising Secret Life of Beavers and Why they Matter”, 2018, by Ben Goldfarb. It’s very interesting and well-written.
Beavers have a mixed reputation, however. They chew down trees and vegetation desired by people, and will flood infrastructure (roads, houses, outbuildings, etc.) in their incessant quest to back up water. All while creating those great wetland habitats for ducks, insects and amphibians.
And they are a rodent! Ick. We generally don’t like rodents. But, beavers are admittedly cute and charismatic, and they have an enormous effect on the ecosystem where they occur. In fact, they are considered one of only a few “keystone species” that have such far-reaching effects.
That’s all easy to appreciate. Beavers are fine “out there” making habitat and storing water somewhere else, but what if beavers come on your property and start chewing trees down and flooding?
Management: Protect your favorite trees. Most trees chewed down by beaver will be relatively close to their water refuge (say within 50 yards). There are some exceptions, but this is usually the case. They will chew on most anything, but some species are preferred, including favorites willow, cottonwood, and aspen. Many of these species are adapted to beavers and immediately produce multiple sprouts from the cut stumps. Sometimes cedars get chewed (even Douglas fir) and if a fruit tree is near a beaver stream, they will definitely chew those.
Trees can be armored with a wrapping of many different types of wire. It needs to reach up high enough that the beavers can’t stand on each other’s shoulders to reach above the wire. Super-beavers have been known to stand on each other up to four high and chew trees off up to 12 feet high (just kidding!). But the armoring does have to be at least 3 to 4 feet high. Lots of wire types work, as long as they are beefy enough to withstand a beaver leaning on it. Check out the recommendations at one of the links below.
Some people have tried paint with lots of grit in it and stinky repellents in attempts to dissuade the persistent chewers. Kent Woodruff, beaver guru of the Methow Valley, notes that none of these things have much success. Your best option to protect a tree is to armor it with wire.
Scare them away? Hard to do. They usually work at night.
Levelers: In situations where there is active dam activity and the water level is intolerable for various reasons, devices are being used to allow them to persist and keep the water at an acceptable level. These are often small culverts inserted into the dam itself, with fencing around each end to prevent the persistent chewers from clogging it up. These need maintenance and are challenging to install, but it can work.
Beaver Deceivers: A clever fence installed around culvert entrances that prevents the beavers from clogging up the culvert, yet allows the beavers to persist.
Removal of the dams: It’s a never-ending task as long as the beavers are present. Many of us can recall a story of someone who got out there in the stream and ripped that beaver dam apart at great effort, only to come back the next day to find it back, exactly the same, or even stronger than before.
Removal of the critters: Due to the wide presence and continuing expansion of beaver populations in Washington, removal of beaver from good habitat is usually going to be a temporary measure.
Life histories of the species mean that usually at age 2, the juveniles will set out and look for a new place to call home. Most beaver pairs have between two and four young each year, and the number heading out looking for home is many.
Suitable habitat, low-gradient streams especially, will likely be recolonized in relatively short order if you are near other occupied habitat. Beavers living in large water bodies such as rivers, and living in bank dens, won’t be noticed until they chew down your trees!
“If there is a good place on the landscape for beavers to live, they will occupy it sooner or later,” Meyer said. “Even if you remove the current occupants, more will come.”
Beavers can be removed by trapping, and in a few areas relocated by working with relocation projects that take them to places where they are welcome. Check out Beavers Northwest (reference below) to see if a project is happening in your area.
Beavers can be legally harvested by trapping or shooting in Washington and are classified as a “furbearer.” Trapping is legal, but traps must not grip the body. The favored trap now is a “suitcase” made of chain mesh and sprung with a powerful spring (photo). A little beaver castor scent on a twig in the middle, and pow! They work.
Beavers live and communicate through their nose, so beaver scents are irresistible to the furry flat-tails. Most areas of the state have licensed animal trappers that can help. There are very few recreational trappers out there anymore, so it is best to work with professionals if removal is your management choice.
WDFW’s furbearer species season dates are November 1-March 31 of each license year, with a trapping license required. Nuisance animals threatening property can be removed at any time. For detailed questions on trapping or other removal methods, contact your regional office of Washington Department of Fish and Wildlife. Here is a link to the trapping regulations at WDFW.
There are some great resources out there about beavers on the landscape, including from Washington’s and Oregon’s state fish and wildlife departments, as well as King County, that can help lead us to good management decisions in regard to our amazing natural wetland engineers.
A great resource for answering many of these specific questions is an organization called Beavers Northwest. They are dedicated to helping people appreciate beavers and resolve conflict issues whenever possible. They also have information about active beaver relocation projects going on in a few areas of the state, including the Methow Valley, for example.
Tolerance and enjoyment: If you are fortunate enough to have beaver on your forest land, be glad! Yes, they will chew some trees and flood a few others (often alder it seems), but will raise your water tables, (especially important in the hot, dry summer), provide habitat for a myriad of species including many birds (think wood ducks and flycatchers) and amphibians (Rough skinned newts and Western toads), and create a wildlife oasis in our forest lands.
I volunteered on our beaver relocation project to get a firsthand sense of beavers and their role. And I did plentiful reading. My eyes were opened and, indeed, I have become a “Beaver Believer!”
Beavers are amazing. Give ’em a chance!
As always, contact me at firstname.lastname@example.org with your wildlife stories and pictures of your personal beaver oasis!