With Respect and a Pond-Leveler, Michigan Field Research Station Strives to Co-Exist with Beavers

As I disassembled their handiwork piece by piece to prevent the gravel Hogsback Road from washing out, I began to learn how beavers construct their dams.

In this case on Carp Creek, which flows from springs between Douglas Lake and Burt Lake in Michigan’s northern Lower Peninsula, they began with a framework of relatively large diameter alder stems from which the branches had been removed. The stems were wedged into the culvert in such a way that they appeared to have been inserted from the downstream side.

The beavers used an increasing variety of species and smaller and smaller branches to build a kind of lattice. It looked like they then proceeded to use the current from upstream to cast and insert stems of various species, with branches intact, into this lattice until the dam became a dense mesh.

I was surprised to find numerous fresh balsam fir stems in the network. With their two-ranked needles forming planes, the fir branches provided vast surface area for trapping sediment.

The beavers then moved sediment from the streambed into the dam. They created deep pools just upstream of the dam where they excavated sediment, pushing it into the dam. As the upstream area flooded, they scoured the bottom, uprooting soil and vegetation and packing it into the dam until it was densely caked with earth and woody debris.

This slowed and spread the streamflow to a trickling waterfall along the dam. Gradually but steadily, sediment would pass through the dam to be deposited on the downstream side. This sediment would create a plain of sandbars, islands, and small braided rivulets below the dam, where new plants would grow.

But this dam couldn’t get to that stage. Before I ended up inside of the culvert, the pond had risen about four or five feet and was remarkably close to washing over Hogsback Road.

I had recently encountered a couple of Cheboygan County Road Commission staff who were evaluating the situation, and we agreed that the road would be at risk if that dam wasn’t removed.

So, there I was, pondering as I removed debris from the culvert. It occurred to me that the bigger problem was that this wasn’t the first dam I had extracted from the culvert. The beavers had evidently determined that this was the place to build a dam, and they were going to keep trying until something stopped them. To their credit, the culvert was the optimal place to build a dam in that stretch of river.

This posed something of a dilemma for me. The easiest solution would be to remove the beavers from the stream. But these beavers were in an area that we have historically considered a “wildlife sanctuary,” where we don’t allow hunting or trapping. If they couldn’t live and thrive here, then where could they? (Admittedly, they seemed to be doing quite well in other areas of our more than 10,000 acres of property.)

Although they are alarmingly destructive, beavers have a natural and historic role in the ecology of this system and in our research and teaching. Many students in ecology classes over the years will recall measuring aspens and alders gnawed by the beavers on Carp Creek during studies of foraging behavior.

In the UMBS archives, I recently saw a map from a 1946 student paper with an illustration of a beaver dam far upstream on Carp Creek.

I have fond memories of my time as a UMBS student, sitting on the bank of Carp Creek watching beavers swim around their pond on a warm summer evening. I’ve walked the length of the stream and observed very old dams and beaver meadows all along its reach, some of which have become difficult to distinguish from their surroundings, but which shape the ecosystems even now.

Another consideration on my mind was the investment beavers make in parental care. Beaver kits typically remain in a lodge for two or three years. Given the complexity of their behavior, I wondered how much of it might be learned, transferred from parents to offspring during their relatively long time together. Did beavers develop cultures?

I became curious about the feasibility of letting the beavers remain in Carp Creek and mitigating their impacts to roads and trails (if not to forests).

I had read Ben Goldfarb’s popular book "Eager: The Surprising, Secret Life of Beavers and Why They Matter," where I became aware of other people around the country developing solutions for this type of problem.

I read about an innovation called a Beaver Deceiver™ developed by a wildlife manager during his time managing beaver-dammed culverts for the Penobscot Nation in Maine. The Beaver Deceiver was essentially a trapezoidal fence extending upstream at an angle from the culvert. When the beavers attempted to extend their dam across the culvert, they would be diverted away and upstream, which somehow confounded them into giving up.

At the U-M Biological Station, we decided to give this technology a try at the culvert on Carp Creek. It was instantly and remarkably successful. The beavers proceeded to build a dam immediately upstream, but the culvert and the road were protected.

Since then, the beavers continued to move upstream building dam after dam. Cutting down alders and bigtooth aspen trees, flooding the swamps and vegetation, dislodging and mobilizing plants and soils, dramatically transforming the land- and waterscape while creating rich habitat for fish, frogs, midges, dragonflies, and waterfowl. Raccoons, coyotes, bobcats, river otters, and birds of prey came to hunt and forage.

Today the beavers have advanced their construction zone well upstream into the Gorge, where they submerged some of our boardwalks under one of their recent ponds. (It turns out that these particular boardwalks were conveniently built on a very old, abandoned beaver dam!)

This situation provided an opportunity to work with another device that I had been thinking about since I read Goldfarb’s book, which is often referred to as a “pond-leveler.”

This is essentially a culvert through the dam with an intake in the pond that is protected by a fence from manipulation by beavers.

Once enough culvert is installed through the dam to accommodate the stream flow, the pond level can be controlled by adjusting the height of the culvert.

So, I approached our skilled and ingenious Facilities Manager, Scott Haley, with some pond-leveler designs. Scott seems to savor the peculiar problem-solving opportunities that arise at our field station, and he and I devised a plan using materials that we could obtain locally.

With an angle grinder and a torch, Scott went to work fabricating a cage for the intake from cattle fencing. We hauled our cage and drainpipe and posts and tools into the Gorge, and after a couple of hours wading in the pond, we had installed our first pond-leveler.

I returned two days later to find the boardwalk flooded again. This became a pattern.

“You look like a beaver,” my wife Stephanie said as I straddled the culvert in my brown hoodie and tried to bury the culvert deeper into the dam by digging with my hands. Stephanie had graciously volunteered to assist me in hauling more materials into the Gorge, undoing the handiwork of the beavers, installing culverts and fencing in chest-deep water…and then repeating the process days later after the beavers restored their dam.

“Now you’re thinking like a beaver,” she said as I bent an alder stem over the culvert to wedge it into the dam. The more I participated in this arguably absurd routine, the more I came to understand the logic and sensibility of the beavers’ behavior.

“Is this foolishness?” I wondered. One could certainly make the case, but it seemed to me that at the extremes, the alternatives were to abandon the popular hiking trail system in this area of the Gorge or to remove the beavers. I wasn’t ready to commit to either of those options, and I was hoping and working to find an intermediate solution.

It has likely always been the case that our lives and activities are incompatible with those of wildlife in various ways and vice versa. But as human civilizations have expanded into and fragmented wild places around the Earth, conflicts between humans and wildlife have increased. And in many cases these conflicts threaten each other’s lives and livelihoods.

The stakes can be very high. The existence of humans and certain wildlife become mutually exclusive. So, there is a growing effort globally to study and address this problem of coexistence with wildlife, which is being led by scientists like Dr. Neil Carter, associate professor at the U-M School for Environment and Sustainability (SEAS).

My attempts to address our local conflicts with the beavers in Carp Creek have been a relatively simple and benign entry into this study and pursuit of coexistence with wildlife. It has exposed me to a community of people in Michigan and the Midwest, in particular, who are engaged in similar efforts. This community has been meeting annually at a Midwest Beaver Summit.

Recently, I have been consulting with a group of graduate students in SEAS who are working on the problem of coexistence with beavers in Michigan. They have offered me advice as I provide them with some context and my practical experiences. The last time I met with them, I was struggling to successfully employ the pond-leveler. I’m pleased to report today that, after some improvements, it finally appears to be working. But the beavers are working, too.

Lately, I’ve been referring to my experiences with the Carp Creek beavers as a “dialogue of labor.” As we repeatedly undo one another’s work to the likely frustration…and joy of the other, what would either of us rather be doing?

Adam Schubel is the U-M Biological Station's resident biologist. The U-M alumnus is responsible for on-the-ground oversight of field research sites, onsite species and habitat conservation, as well as field equipment, permits and teaching collections. He also collects measurements for ongoing, historic data sets about the local ecosystem; is an expert on local flora, fauna and natural history; and leads UMBS site operation for the National Atmospheric Deposition Program and the UV-B Monitoring and Research Program.