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Rare animals
Find rare and non-game animals.
Rare plants
Learn about plants on the Natural Heritage Working List.
Rare lichens
Discover Wisconsin's lichens.
Natural communities
Explore Wisconsin's natural communities.
Other features
Discover unique resources.
Contact information
For information on Wisconsin's natural communities, contact:
Ryan O'Connor
Natural Heritage Inventory Ecologist

Lake Michigan


General natural community overview

Lake Michigan is among the largest and deepest freshwater lakes in the world. This massive waterbody covers 22,300 square miles and has 407 miles of coastline in Wisconsin. The lake is primarily cold water with summer maximum water temperatures below 22 degrees Celsius (72 degrees Fahrenheit). Lake Michigan is relatively infertile, although it is warmer and more fertile than Lake Superior. Historically, the fish fauna consisted primarily of lake trout, ciscoes/whitefishes, and sculpins. Warmer and more fertile harbors and bays (e.g., Green Bay) had a more diverse assemblage of cool and warmwater fishes, especially in the Perch family. Invasion by the sea lamprey due to commercial alterations of the Great Lakes waterways led to the first large-scale disruption of the biotic community, greatly depleting the native lake trout population. By the 1970's, three cisco species were extinct, and three others extirpated from Lake Michigan. Only Lake Superior supports populations of two of these extirpated species, and only Lake Huron supports the third. Over-harvest and other factors caused a steep decline in the population of lake herring. Now the biota is dominated by introduced or invasive non-native species, including Pacific salmon and trout, alewife, rainbow smelt, ruffe, white perch, gobies, zebra and quagga mussels, and exotic zooplankton.

Rare animals

Species of Greatest Conservation Need

Wisconsin Wildlife Action Plan graphic

The following Species of Greatest Conservation Need are listed according to their level of association with the natural community type, based on the findings in Wisconsin's 2015 Wildlife Action Plan.

Scores: 3 = high association, 2 = moderate association, and 1 = low association. See the key to association scores for complete definitions.

A Hydroporus Diving BeetleHeterosternuta pulchra2
Hairy-necked Tiger BeetleCicindela hirticollis rhodensis2

Caspian TernHydroprogne caspia3
Common TernSterna hirundo3
Common GoldeneyeBucephala clangula2
Black TernChlidonias niger1
Forster's TernSterna forsteri1
Great EgretArdea alba1
Peregrine FalconFalco peregrinus1
Purple MartinProgne subis1

Dragonflies and damselfliesScore
Alkali BluetEnallagma clausum1
Painted SkimmerLibellula semifasciata1

Lake SturgeonAcipenser fulvescens3
American EelAnguilla rostrata1

Grasshoppers and alliesScore
Lake Huron LocustTrimerotropis huroniana2
Seaside GrasshopperTrimerotropis maritima2

Big Brown BatEptesicus fuscus2
Little Brown BatMyotis lucifugus2
Silver-haired BatLasionycteris noctivagans2

Please see Section 2. Approach and Methods of the Wildlife Action Plan to learn how this information was developed.


The following Ecological Landscapes have the best opportunities to manage for , based on the Ecological Landscapes of Wisconsin Handbook.

Major (3 on map)
A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important (2 on map)
Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present (1 on map)
The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.


Wisconsin Wildlife Action Plan graphic

What are conservation actions?

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for natural communities




Dolomite pavement ("Great Lakes Alkaline Rockshore") on Hog Island, part of the Grand Traverse Islands Archipelago north of the Door Peninsula.

Photo by Emmet Judziewicz.


This remote, unvegetated Lake Michigan island is composed almost entirely of dolomite cobbles. This island provides nesting habitat for several species of colonial birds. Door County, Northern Lake Michigan Coastal ecological landscape.

Photo by Emmet Judziewicz.


Aerial of the Eagle Bluff an outcrop of the Niagara Escarpment along Green Bay. Peninsula State Park, Door County.

Photo by Eric Epstein.


Great Lakes Alkaline Rockshore and Boreral Forest, south end of Toft Point, Door County.

Photo by Eric Epstein.


Shallow bay of Lake Michigan, Great Lakes Alkaline Rockshore, mixed borealXnorthern hardwoods forest. Northern Door Peninsula.

Photo by Eric Epstein.

Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.

Last revised: Friday, February 15, 2019