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Mississippi River Endangered Resources

Endangered Resources in the Mississippi River Corridor

The bluffs which overlook the Mississippi River are an extension of the steep hills and ravines of a distinctive area that covers southwestern Wisconsin as well as southeastern Minnesota, northeastern Iowa and the northwest corner of Illinois. In Wisconsin this region is commonly called “Coulee Country” (coulee is a French word for valley or ravine.) Geologists call it the “Driftless area, which means the area was ice-free during the last glacier stage of the ice age and is free of glacial sediment or drift.

As the great glaciers ground slowly across much of what is now Wisconsin, crushing hills and filling valleys, they scraped and flattened the landscape. But in the Coulee region, erosion shaped the landscape as river valleys were carved into the limestone bluffs, creating the pattern of steep hills, ridges and ravines we have today. The varied terrain of the Western Coulees and Ridges Landscape is not only pleasing to the eye but it is also extraordinarily diverse biologically.

Prior to European settlement this region supported a mosaic of prairie, oak savanna, oak forest, and maple-basswood forest on the upland with floodplain forest and marshes along the large rivers of the region. Today a large number of the Endangered and Threatened Species of the Western Coulees and Ridges Region and the Mississippi River corridor consist of plants and animals that depend on the remnants of these natural communities. Efforts have been made to protect and preserve some of these special habitats in Wisconsin through the Endangered Resources and Natural Areas programs. In addition, other sites have been identified through the Land Legacy Program.

The Mississippi River Corridor

Prairies are one of the most endangered types of natural communities in the upland portion of the Mississippi River corridor. Prior to settlement the presence of fire maintained prairie and oak savannas. But m uch of this native prairie was a casualty of the plow, while other patches gradually converted to forest due to the control of wild fires. Along the Mississippi River there are currently two types of prairie remnants that are of special concern, goat prairies and sand prairies .

Goat Prairies (dry prairies)

The bluffs on the Wisconsin side of the Mississippi River valley have predominately southern or western exposures which were once covered by dry hillside prairies and oak savannas. These prairie remnants, often referred to as goat prairies were named because they are “to steep to plow and only fit for a goat to graze,” have managed to persist because of a combination of factors that result in droughty conditions.

Goat prairies are usually located on slopes exposed to prolonged periods of intense sunlight which, during the growing season, results in a very hot, dry microclimate. They are also invariably found on thin soils overlying bedrock. The combination of dry microclimate and thin soils creates a desert-like environment that can be inhospitable to all but the most drought-tolerant species, thus the slow invasion of woody species into those prairies. However, given enough time, and in the absence of fire, even the driest and steepest of bluff prairies will yield to the slow advance of shrubs and trees. Numerous goat prairies on the bluffs bordering the Mississippi River are now almost covered by stands of red cedar interspersed with birches. As a consequence plants and animals that depended on these special habitats have declined markedly.

 

Sand Prairies

River terraces, formed along the Mississippi River during the end of the ice age, were historically covered with vast expanses of sand prairie. Because the terraces provide level land they have been used as locations for communities and intensively used for agriculture. The remaining parcels of viable sand prairie are threatened by development.

Some of the state threatened and endangered species of dry and sand prairies include:

Birds

  • Bell ’s Vireo - Threatened
  • Greater Prairie Chicken - Threatened
  • Loggerhead Shrike - Endangered

Reptiles and Amphibians

  • Blanding’s Turtle, Wood Turtle - Threatened
  • Eastern Massasauga Rattlesnake - Endangered
  • Ornate Box Turtle - Endangered
  • Western Slender Glass Lizard - Endangered
  • Wood Turtle - Threatened

Blanding’s Turtle laying eggs

The Mississippi River

A lthough the Mississippi River still supports an amazing variety of aquatic life, there are species including fish, freshwater mussels, turtles, and birds that have been impacted by the extensive changes that have occurred to the river over the last 100 years.

Fish

The most dramatic change was the result of the building of the locks and dams to maintain the 9-foot navigation channel. During this process gravel bars and shallow places were removed or flooded and ultimately the free flowing river was changed into a system of navigation pools or reservoirs. These changes significantly impacted species such as lake sturgeon, paddlefish, blue sucker, crystal darter and skipjack herring. .

Fish species listed as state endangered or threatened include:

 Freshwater Mussels

In addition, other changes which occurred as a result of the dams including water depth, velocity of currents, and water temperature negatively affected the Freshwater Mussels of the Upper Mississippi River .

Freshwater mussels listed as state threatened or endangered include:

Birds

Many of the bird species listed as Endangered and Threatened Species of the Western Coulees and Ridges Region are also found in the Mississippi River Corridor. The current status of the most widely known include:

Peregrine Falcons

Peregrine falcons had essentially disappeared from this part of the Mississippi River by the late 1950s due to the effects of DDT. This pesticide was passed through the food chain, eventually reaching the peregrine falcon. The concentration of chemicals in the peregrine’s system caused females to lay eggs with very thin shells which either didn’t hatch or were crushed under the weight of the incubating adult.

Recovery efforts along the Mississippi River began in the mid 1970's using traditional cliff sites as release locations but the attempts were unsuccessful as the released birds were picked off by great horned owls. Nesting attempts on the cliff sites in the 1980's failed for similar reasons. Consequently the recovery efforts moved away from the more natural habitat and used urban release sites such as tall buildings and eventually smokestacks of power companies located along the river. Peregrines were very successful on the smokestacks and built up their numbers to the point where young birds, looking for a place to nest, started to move back onto the traditional cliff sites overlooking the Upper Mississippi River.

Wisconsin Status: Endangered

Trumpeter Swan

Trumpeters nested in Wisconsin until the 1880s. Originally they may have nested in all but the northeastern forested regions, most likely in large marshes or shallow lakes. However by 1900, it was widely believed that the species had become extinct nationwide. However, remnant populations were discovered at Red Rocks Lake in Montana. Several Midwestern states have launched restoration programs to reintroduce Trumpeter Swans including Wisconsin. Eventually these flocks will help create amigratory and breeding population in the Midwest. In 2007, three trumpeter swan nests were found on the Upper Mississippi River bordering Wisconsin.

Wisconsin status: Endangered

Bald Eagle

The Bald Eagle was declared endangered in 1973 but is no longer state listed as endangered or threatened. Today the Bald Eagle is a familiar resident along the Upper Mississippi River during nesting season. In 1972 there was one nesting pair; now there are well over one hundred. The river also serves as a well known wintering site. In 2006, over 1000 eagles were counted in 117 miles of river during the annual midwinter aerial count conducted by the WI DNR.

The bald eagle was taken off the endangered list in Wisconsin in 1997 and may be taken off the f ederal list on June 29, 2007.

For more information on any of the species listed above clink on the link Endangered and Threatened Species of the Western Coulees and Ridges Region and select the category and species.

Last Revised: June 8, 2007