September–October 2023


A Friend of the Bog

Naturalist Clinton Dexter-Nienhaus is a peatland champion. 

Carolyn Howell

For the uninitiated, the many peat bogs scattered across the state’s north might seem like nothing more than soggy, squishy, hard-to-access wetlands. Plus, there are mosquitos—lots of mosquitos—in a bog. What could be so special? For Clinton Dexter-Nienhaus, a Minnesota native with a master’s in environmental education from University of Minnesota Duluth, this landscape is a place of beauty, mystique, and opportunity. Dexter-Nienhaus is head naturalist at Friends of Sax-Zim Bog, a nonprofit that owns and protects 4,200 acres of a much broader landscape of spruce and tamarack bogs and other habitat types spanning 300 square miles in northeastern Minnesota. The organization strives to preserve the bog’s biological diversity and educate the public about this poorly understood biome. More than 3,200 plant and animal species have been documented here, including some 240 bird species that attract visitors from around the world. (Dexter-Nienhaus and his wife, Kristina, recently spent a day exploring the peatland landscape and spotted 400 individual species of birds, plants, insects, and animals.) We chatted with the naturalist about the state of Sax-Zim Bog, including how climate change might affect this soggy, squishy, magical place. 

Q | What makes bogs so biodiverse?
It all comes down to specialization. It’s a hard place to live. The soil is generally nutrient poor and acidic. You’re hitting 80 to 90 degrees in the summer and 40 to 50 below in the winter. And when we think about plant communities, where you have specialist plants, you tend to have specialist insects. Four plants can harbor 40 or 50 insect species, and those insects have predators like birds or other insects. And then if you translate that to all the other little biomes, you’re building a really wild place filled with things that are perfectly designed to be there. That piece is so critical when thinking about peatlands. If you lose black spruce and tamarack, for example, you’re not just losing the trees; you’re losing the birds and understory capacity. The habitat quality, the habitat diversity, and all those things working together make this lovely mosaic of biodiversity.

Q | What prompted the founding of Friends of Sax-Zim Bog?
It was started in 2010 by Sparky Stensaas, Kim Eckert, and Dave Benson as an organization to be a voice for the bog landscape. They had noticed an increase in black spruce and tamarack logging in the area, and they got together. That’s how things got started. Land preservation was the initial goal of the organization, and it’s grown to include the education and outreach piece, especially with local folks. 

Q | What is your role as head naturalist?
The easiest way to think about this position is as an environmental education position where I’m doing traditional naturalist work as well. I’m organizing nearly all the education and programming, but I also get the chance to go out and do other things like finding and IDing species in the bog. For me, learning about what’s out there really helps inform the education piece. All our programming is on our website at, and I encourage people to check that out.

Q | Why is Sax-Zim so important for migratory birds?
Some of it has to do with where we are geographically, since nearby Duluth is a major migration corridor. We have about 120 species that come here to nest. A lot of the species come from high northern boreal forests, and those species are pushing as far south as the tamarack and black spruce forests get. Others, like the scarlet tanager, are pushing as far north as they get because their habitat is also there. Some birds, like the pine grosbeak, come for food that they don’t have farther north in the winter. Sprinkle in some hayfields and jack pine barrens and you get some really cool stuff going on with the birds year-round.

Q | What are some tips for the upcoming winter birding season?
The species that winter here start showing up around the end of October and the mid part of November. Starting then we can get an idea of what birds will be here for the winter. You can see a lot of the same birds from December to about March, when they leave again. Around then, breeding season starts for a lot of the northern species like Canada jays, ravens, and great gray owls, so they will stay. But if you’re coming to bird in the winter, there’s not a lot of difference between the months. You’ll usually see great grays, boreal chickadees, pine and evening grosbeaks, white-winged crossbills, and redpolls, among many others.

Q | Are bogs at risk from climate change?
Absolutely. They’re a climate-sensitive ecosystem. Most bog species are cold adapted, but not necessarily well adapted to the warm. If we think about birds, the Canada jay is a good example of that. In Ontario, they’ve already seen a shrinking range for the Canada jay due to the warming climate. What will happen to the bog in 40 or 50 years? What are peatlands going to look like? I don’t know. We should expect that things are going to change, but what that means for bird and plant communities, I’m not sure.

Q | What about the carbon emissions research happening at the bog?
The Nature Conservancy is doing some work here on the power of intact peatlands. It’s a valuable effort to understand how peatlands sequester carbon, and how disturbances affect their function. They’ve found that drainage ditches in bogs introduce oxygen into that ecosystem, which starts to break down the peat and release the carbon. So we’re learning that intact peatlands are very important from that perspective.

Q | What are some other projects happening at the bog?
There’s usually a research piece that we’re doing, whether it’s supporting outside research or doing our own. We have kestrel banding and monitoring that we’re doing. There are raptor surveys in the winter. We do our biological surveys in the spring. There’s a radio telemetry tower behind the welcome center that can help with research, bird movements, and migrations. And volunteers have been important as well. Folks help with our feeders, kestrel monitoring programs, building boardwalks, and supporting staff at the welcome center.

Q | What are your favorite things at the bog?
One group that has always been fun are the moths. My wife got me into moths, and I think our biological surveys have identified 667 species so far. For us, being out in the bog at night to see the moths is really cool. I think that’s part of the bog that is undiscovered by folks, because they’re not there at one or two in the morning. I also like being in the bog when it’s really cold. There’s something about experiencing 30- or 40-below temps and seeing chickadees and pine grosbeaks doing just fine. And the sphagnum moss diversity is something I didn’t have a good grasp on until a couple of years ago. There are orchids, dragonflies, so many cool things!