Are beavers always the answer? Not really

By Ted Williams

Beavers, through their assiduous dam building, can recharge groundwater and provide habitat for fish and wildlife. In the Pacific Northwest, for example, managers are bringing back beaver as part of trout and salmon management.

“God bless beavers and their industrious nature,” writes Trout Unlimited’s Idaho-based Chris Hunt in Hatch magazine. “They make habitat for the fish we love, and opportunities to catch them.” True enough, in Idaho.

But the notion, ubiquitous in America, that all beavers everywhere are a panacea for what ails an ecosystem is misinformed. Yes, beavers are beneficial — in the right places.

In the wrong places watersheds degraded by humans — they’re a scourge. The environmental community and the public tend to have trouble grasping these two realities simultaneously.

In his essay “Thinking Like a Mountain,” Aldo Leopold, father of wildlife management, described how killing wolves for the supposed benefit of deer resulted in obliterating deer habitat along with the deer themselves. Everything he wrote about deer applies equally to beavers. Both species depend on essentially the same forage — in unnatural abundance because of massive logging — and the main predators of both are wolves, extirpated throughout most beaver and deer ranges.

Beavers affect native ecosystems the way red wine affects human bodies: One glass a day helps the heart; 20 blows out the liver.

In the wrong places, beavers grossly overpopulate, blocking trout migration, stripping streamside cover, choking spawning gravel with silt and muck, and converting oxygen-rich streams to dead water. That’s because humans have eliminated wolves and old growth from most of the West, and stream corridors now grow willow and aspen — beaver candy.

Consider the debacle in Nevada. This from Kim Toulouse, the Nevada Department of Wildlife’s former conservation educator: “Historically, virtually every stream in the northern half of Nevada held some form of cutthroat trout. Additionally, many small-order streams also held native redband and bull trout. When the push started (for trout recovery) we discovered that many single-order streams were infested with heavy populations of beavers.

“Extremely high numbers of beaver dams on these systems led to loss of gene flow and precluded the ability of fish to move up and down these systems. Additionally, fish found it difficult to find suitable spawning grounds due to heavy siltation caused by the dams. The loss of riparian habitat led to erosion, more siltation, less shade, higher water temperatures, loss of native riparian vegetation, and establishment of noxious invasive plants.”

So Nevada initiated major beaver control. But politicians, incited by the Humane Society of the U.S., shut it down.

Beaver damage to Minnesota and Wisconsin trout streams is even worse. Fisheries managers have to hire Wildlife Services, a federal agency, to trap beavers and blow up dams. It’s expensive, so only a small percentage of streams can be salvaged.

And Trout Unlimited reports that in Minnesota’s Knife River watershed, “artificially high beaver numbers…threaten the survival of coldwater fisheries, as well as the health of the watershed and Lake Superior.” But an outfit ironically called “Advocates for the Knife River Watershed” is fighting to nix beaver control, circulating junk science and such fictions as “beaver have been totally eradicated in the whole Knife River valley — over 200 square miles.”

California’s Silver King Creek watershed is the only refuge for threatened Paiute cutthroat trout, yet overpopulated beavers block migration and destroy habitat. It got so bad in Four-Mile Creek that Trout Unlimited volunteers had to reroute the stream.

“The biggest problem I see is that beavers move into an area that doesn’t have enough forage, and they abandon their dams,” said retired state fisheries biologist Bill Sommer. “When beavers leave, the dams blow out and that causes erosion.”

Aldo Leopold could grasp two realities about deer simultaneously. Were he still alive, he’d applaud Phil Monahan, who wrote this in Trout Unlimited’s Trout Magazine: “Many anglers see the beavers’ work as predominately destructive — turning a babbling trout stream into a slow-moving wetland, for instance. Wildlife biologists recognize that each of these ‘destructive’ effects has a flip side: situations in which that very same effect is beneficial to trout.

“After looking at all the data, then, the question, ‘Are beavers good or bad for trout streams?’ can be answered only with a definitive: ‘It depends.’”

Ted Williams is a contributor to Writers on the Range,, an independent nonprofit dedicated to spurring conversation about the West. He writes for several national publications about wildlife.

This column was published in the following newspapers:

10/09/2023 Portland Tribune portland or
10/09/2023 Forest Grove News Times Forest Grove OR
10/09/2023 Beaverton Valley Times Beaverton OR
10/10/2023 Fort Morgan Times Fort Morgan CO
10/10/2023 Sterling Journal-Advocate Sterling CO
10/09/2023 Sherwood Gazette Portland OR
10/09/2023 Valley Times News Portland OR
10/09/2023 Columbia County Spotlight Scappose OR
10/09/2023 The Newberg Graphic Newberg OR
10/11/2023 Aspen Daily News Aspen CO
10/11/2023 Montrose Daily Press Montrose CO
10/12/2023 Wyoming Tribune Eagle Cheyenne WY
10/12/2023 Denver Post Denver CO
10/11/2023 Wallowa County Chieftain Enterprise OR
10/09/2023 Hillsboro Times News Hillsboros OR
10/10/2023 Vail Daily Vail CO
10/12/2023 Taos News Taos NM
10/13/2023 Laramie Boomerang Laramie WY
10/13/2023 Glendive Ranger Review Glendive MT
10/15/2023 Twin Falls Times News Twin Falls ID
10/15/2023 Carlsbad Current-Argus Carsbad NM
10/15/2023 Yahoo sunnyvale ca
10/15/2023 Glenwood Post Independent Glenwood Springs CO
10/15/2023 Alamogordo Daily News Alamogordo NM
10/15/2023 Ruidoso Daily News Ruidoso New Mexico
10/15/2023 Farmington Daily Times Farmington NM
10/15/2023 Pueblo Chieftain Pueblo CO
10/15/2023 south dakota searchlight Pierre SD
10/15/2023 Las Cruces Bulletin Las cruces NM
10/20/2023 Bandon Western World Bandon OR
11/04/2023 Brush News Brush CO
11/01/2023 East Oregonian News Pendleton OR
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Kay Charter
7 months ago

I think it’s getting better in my area in Northern Michigan: The wildlife biologists
here are well educated on the issues around
true conservation.

Warren Winders
7 months ago

Thanks Ted for bringing some ecological reality to the table. Beavers, like deer, play a role. That role becomes distorted in the absence of a fully function ecosystem… one that has the predators to keep numbers in check.

7 months ago

Good column. Arrrrrgh, why are the Humane Society and its buddy groups in charge of wildlife policies in some states? How ridiculous! Some problems like climate change are complicated and horribly hard to solve, and that makes it even more frustrating when problems that could be much more easily solved, like deer and beaver overpopulation, are not solved because of human ignorance and bad politics. My own rural state is under the giant thumb of the Farm Bureau, and that is very hard to change. But couldn’t the political yoke of the Humane Society be more easily thrown off?

Cass Martinez
7 months ago

I’m in the middle of reading Beaverland… currently enjoying chapter 9 (effects on land and water) and looking forward to chapter 13 (co-evolution with fish).

Terry Moores
7 months ago

I will start out by saying I dont like the reintroduction of wolves into the ecosystem here in SW Colorado, or anywhere I would like to go on a hike. As far as beavers go I see that as a weak excuse. Us humans can control the beavers a lot more efficiently than wolves and do it humanely to relocate them where they will do some good.
I have been attacked by pet dogs running in a pack even though some of them were known to me through friends and were nothing but friendly one on one. They had to be reverting to their primitive instincts which wolves still possess. I run into bears frequently while hiking in the La Platas and the San Juans and they make me nervous enough. I am 74 and could easily be seen by a pack of wolves as something vulnerable and easily brought down due to the hitch in my get along.
And as for deer, I live in a mountain valley and get around the surrounding mountains quite a bit. I havent seen any place that comes close to being overrun with deer.
I dont want to have to carry a gun or hike in a crowd for protection either.

Ted Williams
7 months ago
Reply to  Terry Moores

Humans have proven their inability to “control beavers,” as you would have learned had you paid attention to my piece. I didn’t make up the facts I reported. Check them out yourself. That’s easily done. Not sure what point you are making with the pet-dog attacks. As for wolves, worry not. They don’t attack humans. The fact that you haven’t seen places in your Colorado mountain valley “overrun by deer” doesn’t gainsay the fact that the East is overrun by deer. My son, Dr. Scott Williams, is a deer biologist in Connecticut. A 10-year study by the U.S. Forest Service reveals that, at more than 20 deer per square mile, there’s complete loss of cerulean warblers, yellow-billed cuckoos, indigo buntings, eastern wood pewees, and least flycatchers. At 38 deer per square mile, eastern phoebes and even robins disappear. On my son’s research areas he’s had as many as 100 deer per square mile. If you would like to learn about deer overpopulation in the East, I direct you to my piece in Estuary Magazine at:

Liz vD
6 months ago

Hi Ted, can you please provide the sources you relied on for some of the claims you make in this article? In particular, I’m curious about what research you referenced for the following: ” beavers grossly overpopulate, blocking trout migration, stripping streamside cover, choking spawning gravel with silt and muck, and converting oxygen-rich streams to dead water”. Thanks in advance!

Ted Williams
6 months ago
Reply to  Liz vD

I mentioned two in the piece — Bill Somer and Kim Toulouse.

Also: Marc Bacigalupi, Brainerd Area, MN

Jeff Tillma, fisheries biologist, MN DNR

Jason Suckow, Minnesota and Wisconsin Wildlife Services State Director

William J. Paul, Minnesota Wildlife Services
Deserae Hendrickson, MN DNR Duluth Area Fisheries Supervisor

Todd Richards, assistant director of fisheries, Mass. Division of Fisheries and Wildlife

Max Wolter, DNR fisheries biologist, Hayward, Wis

Jen Johnson, fisheries biologist, Michigan DNR

Bill Bakke, Native Fish Society

Kurt Beardslee, director, Wild Fish Conservancy

Deserae Hendrickson
MN DNR Duluth Area Fisheries Supervisor

Dr. David Wattles, MA

Ted Williams
6 months ago
Reply to  Liz vD

PS: Not room here for all transcripts from my notes. But here are some of the more pertinent ones:
Wisconsin DNR fisheries biologist Scott Braden: “Beaver Creek and Buckhorn Springs were really beaten up by beavers. There was some brook trout reproduction in the headwaters. But they couldn’t get downstream; they were basically gone. All that was left were dark, sedimented backwater sloughs full of lily pads. It was just terrible. We were walking through chest-deep muck. It really gave you an idea of how much damage overpopulated beavers do. After Wildlife Services trapped beavers and removed dams, that cold water started rushing downstream and scoured out all that muck and debris, making lots of habitat. Within two years, there were just thousands of brook trout throughout the system.”

Minnesota fisheries biologist Jeff Tillma: “Forest management here is geared toward aspen, and the rotation is about forty years. That means there are lots of young aspen on the landscape, and that creates prime beaver habitat. Also there’s a lack of shade and large woody input in the streams. Wood isn’t allowed to get old. The trees beavers cut down are so small, they don’t stay put. We’d like better coordination between forestry and fisheries for longer-lived, uneven-aged management. Our beaver management is small scale because of the expense. We do only a handful of streams in each area, and we do them annually. If we stop for any length of time, beavers return. We’ve seen very encouraging results—more and larger brook trout.
Kim Toulouse, the Nevada Department of Wildlife’s former conservation educator: “The Truckee River, where they’re trying to recover Lahontan cutthroat trout, is overrun with beavers — bank dwellers because the mainstem is too big for dams. On a number of reaches, beavers have decimated the entire cottonwood population on both banks. That has removed shade and insect populations, primarily terrestrials. Replacing the cottonwoods have been mainly [nonnative] invasives like tall whitetop. It’s very difficult to treat. It takes over everything, and it releases a toxin that prevents the spread of natives.”

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