Grand River Fen Preserve is home to the longest river in the state of Michigan, the Grand River.
Stream at Grand River Fen Preserve Grand River Fen Preserve is home to the longest river in the state of Michigan, the Grand River. © Jason Whalen

Places We Protect

Grand River Fen Preserve


This fen is critical habitat for special insects and a globally-rare plant, the bog bluegrass.

Grand River Fen Preserve contains the second largest high-quality occurrence of cinquefoil-sedge fen in the North Central Tillplain Ecoregion. This 453-acre complex of high quality wetland communities also includes southern swamp and southern shrub-carr. This makes it critical habitat for special insects, including the blazing star borer, tamarack tree cricket, pine tree cricket, regal fern borer, angular spittlebug and red-legged spittlebug. One globally-rare plant, the bog bluegrass, is also found here, as well as a very high diversity of flowering plants, sedges, and grasses.

Why TNC Selected This Site

Three separate areas of high-quality prairie fen are the heart of this site. These are renowned among lepidopterists for the diversity of butterflies and moths, including four globally rare species. The wetlands occupy a glacial outwash channel that forms a portion of the headwaters of the Grand River. The fens and associated swamp and upland forest communities harbor a regionally significant and diverse fauna and flora including seven globally rare and eight state-rare species. While progress should never come to a halt, there are some places it should never come at all like headwater streams, wetland complexes, and rare Great Lakes marshes.

What TNC Has Done/Is Doing

The Nature Conservancy has set forth multiple conservation targets and ecological objectives for the Grand River Fen Preserve. Grand River Fen is one of our most active restoration and management sites.

Conservation Targets

  • The complex of high quality wetland communities, including prairie fen, southern swamp, and southern shrub-carr.
  • Populations of globally-rare insects and plants, including the tamarack tree cricket, the blazing star borer, the pine tree cricket, the silphium borer moth, the angular spittlebug, the Poweshiek skipperling, and bog bluegrass.
  • Populations of other rare animals, such as the regal fern borer and red-legged spittlebug.

Ecological Objectives

  • Protect the mosaic of wetland and upland ecosystems and key ecological processes, especially the cycle of groundwater recharge and discharge that maintains the prairie fens and associated rare animals and plants.
  • Locate, protect, maintain, and enhance the populations of globally rare insects.
  •  Use controlled burns and invasive species management in the prairie fens and dry prairies to improve rare insect populations.
  • Evaluate restoration of degraded dry prairie sites and other formerly open uplands.


Access to this preserve is limited to field trips and volunteer workdays. Please email if you are interested in participating or visit our volunteer webpage.

The Nature Conservancy allows hunting for white-tail deer on this preserve to reduce an unnaturally high deer population in the area and reduce threats too many deer pose to our conservation targets. All hunters are required to receive a permit from TNC as well as a Michigan deer hunting license. Additionally, hunters must report any deer taken from the preserve.

What to See: Plants

  • Blazing star: Several species of this showy plant occur in the fen. With a narrow spike of bright purple flowers, they somewhat resemble the invasive plant Purple Loosestrife (Lytrhrum salicaria), but these are all native. Some blazing stars occur in dry prairies, and others grace prairie fen wetlands.
  • Bog Bluegrass: Populations of Bog Bluegrass are typically found in spring-fed swamps in Indiana, Michigan, Minnesota, and Pennsylvania. Blooming occurs in late May to early June, and the flowers last for only a week or two. This species is closely associated with water — thus factors which adversely affect surface water chemistry or water table fluctuations would be most influential on this species’ growth and distribution.

Natural Communities

  • Prairie fens: Geologically and biologically unique wetlands found only in the glaciated Midwest, they are distinguished from other ‘chalky’ fens by a tall grass prairie flora and fauna component. Sapric peat is typical prairie fen substrate, which is saturated with a constant supply of groundwater. Groundwater is calcareous, or rich in both calcium and magnesium bicarbonates; resulting from flow through coarse textured calcareous glacial deposits.

What to See: Animals

  • Native butterflies occur in very high abundance at Grand River Fen. This site has long been known by lepidopterists for its diversity of these beautiful insects. Species like the Baltimore Checkerspot (Euphydryas phaeton) may follow you around, seeking the salt in your sweat.
  • Powesheik skipper has declined rapidly from its once wide distribution, and is now surviving mostly in Minnesota and the Dakotas, with a few declining populations in the Great Lakes region. Like many prairie species, the Powesheik skipper has suffered tremendous losses of its native habitat.
Grand River Fen Preserve See the start of Michigan’s longest river as it begins nestled in a protected area that provides habitat for fluttering butterflies and dazzling wildflowers.