Open Bog-Muskeg

habitat photo
Photo 1 | Photo 2 | Photo 3 | Photo 4 | Photo 5
Muskeg. Cedar Lake Road, Iron County. Photo by Ryan Brady.

Habitat Description

Habitat Crosswalk

Cowardin: Palustrine; moss-lichen; scrub/shrub, deciduous, evergreen, needle-leaved, broad-leaved (Cowardin et al. 1979).
Shaw and Fredine: Type 8: Bog (Shaw and Fredine 1971).
Vegetation of Wisconsin: Open bog (Curtis 1971).
Wisconsin Department of Natural Resources Natural Communities: Open Bog, Muskeg, Bog Relict, Patterned Peatland (WDNR 2005).
Wisconsin Wetland Inventory: Moss; scrub/shrub, deciduous, evergreen, needle-leaved, broad-leaved (WDNR 1992).


Open bogs and muskegs represent a gradient between open and partially wooded peatland communities and consequently share numerous common features. Both are typically formed in closed basins and receive nutrients almost entirely from precipitation. True bogs and muskegs are effectively isolated by peat deposits from contact with nutrient enriched ground or surface waters. The plant composition of bog and muskeg is influenced by peat depth, position of the water table, and pH. For instance, many bog species reach their southern range limits in Wisconsin where poorly drained, nutrient-poor, highly acidic organic peat soils occur. Plants common to and characteristic of both bogs and muskegs include mosses, sedges, and ericaceous shrubs. “Peat” mosses of the genus Sphagnum form a continuous, often hummocky surface. Among the characteristic sedges are few-seeded sedge, boreal bog sedge, star sedge, and tussock cotton-grass. Common ericaceous bog shrubs include leather-leaf, bog-laurel, and small cranberry (Curtis 1971, Hoffman and Mossman 1993, Lachance and Lavoie 2004). Both open bog and muskeg may occur within a wide variety of ecosystems and glaciated landscapes, ranging from temperate hardwood forests to boreal spruce forests, and within landscapes often heavily transformed by human activity (Calme´ et al. 2002).

Despite these similarities, woody cover differentiates open bogs from muskegs. Whereas trees are essentially absent from open bog habitats, muskegs typically support scattered black spruce, tamarack, or other tree species tolerant of highly acidic soils. The extreme soil conditions often compromise tree growth and result in stunted trees present at low densities (Curtis 1971, Hoffman and Mossman 1993). Even minimal tree cover, however, can influence the overall plant assemblage and its distribution within a muskeg (Lachance and Lavoie 2004). For instance, the ericaceous shrubs Labrador-tea, creeping-snowberry, and low-bush blueberry, and three-seeded sedge may dominate the groundlayer of areas shaded by dense growth of black spruce.

Historical and Present-day Context and Distribution

Although the historical extent of each habitat type is unknown, bog and swamp communities as a whole formerly covered approximately 950,000 hectares in Wisconsin prior to European settlement. Today, approximately 346,000 hectares (36%) remain, primarily north of the tension zone (Hoffman and Mossman 1993). A few isolated relic stands occur south of the tension zone, particularly in the Kettle Moraine district of Waukesha and Walworth counties and in certain recessional moraines in Jefferson and Columbia counties. Bogs are almost always located on glacial landforms, including poorly drained moraine, outwash, ice block (“kettle”) depressions, or lakebeds. Many kettle bogs are associated with an active or extinct glacial lake (Curtis 1971, Hoffman and Mossman 1993).

Natural Disturbances and Threats

Disturbances to peatland communities can radically modify their structure and function and reduce their value to bog-associated species. For instance, hydrological changes within a bog system can lead to the colonization of different plant and animal communities. Higher water levels can inundate bog mats, raise nutrient levels, and allow marsh habitat to develop. Alternately, lowering the water table dries surface peat layers, enables the spread of fire, and may lead to an increase in woody plants. Fire can establish conditions suitable for forest bird species by creating an excellent seed bed for black spruces and encouraging the growth of balsam fir, white pine, or jack pine (Hoffman and Mossman 1993). When fire removes a considerable volume of the peat surface layers, a hybrid community of open bog and sedge meadow may develop (Curtis 1971, Hoffman and Mossman 1993). 

Peat mining, urban development, construction of roads and other types of right-of-way, and agriculture can facilitate major biological changes within a bog system, with small bogs being particularly susceptible. Each has the potential to alter the original plant community by either directly destroying the flora (i.e., filling, land-leveling), introducing nutrients to an otherwise closed system, or severely altering water table levels (Mazerolle and Cormier 2003, Tiner 2003, Lachance and Lavoie 2004). These disturbed conditions reduce colonization of native bog flora (Desrochers et al. 1998) and instead support colonization by disturbance-tolerant species such as beggarticks and smartweeds (Hoffman and Mossman 1993). Thus, unless restorative actions are taken, disturbed peatlands likely will not serve as ecological substitutes for natural, undisturbed systems (Desrochers et al. 1998).

Related WBCI Habitats: Northern Sedge Meadow and Marsh, Black Spruce, Tamarack.

Overall Importance of Habitat for Birds

Peatland habitats host a suite of species with diverse habitat requirements. Open bog habitats support many open country birds generally associated with grasslands while muskegs support many species associated with forests. Several open country species, such as Sedge Wren, Savannah Sparrow, and Swamp Sparrow, nest in open bogs containing dense ground vegetation. As tree cover increases and open bog transition into muskeg, forest species such as Gray Jay, Yellow-bellied Flycatcher, Ruby-crowned Kinglet, Hermit Thrush, and Yellow-rumped Warbler occur. The stunted trees and snags within muskegs provide cavity nest sites for Black-backed Woodpecker and Boreal Chickadee and perch sites for Olive-sided Flycatcher. Wetland-associated species also are well-represented across these habitats. With the presence of water, Trumpeter Swan, American Black Duck, Green-winged Teal, and Ring-necked Duck may nest. Common Yellowthroat, Yellow Warbler, Song Sparrow, and Red-winged Blackbird also are common associates of peatland habitats. Larger bogs are used for nesting, foraging, or roosting by several area-sensitive species, such as the Northern Harrier, Short-eared Owl, and even Sharp-tailed Grouse, which is typically associated with dry upland areas (Howe et al. 1992, Hoffman and Mossman 1993).

Open bogs and muskegs are important to maintaining local avian diversity in Wisconsin. Palm Warbler is considered a peatland specialist and prefers to nest in muskegs with sparse tree cover and heavy undergrowth of shrubs and sphagnum moss (Niemi and Hanowski 1992, Wilson 1996, Desrochers et al. 1998). Several other species reach the southern edge of their breeding range in Wisconsin’s peatlands. Nashville Warbler, Connecticut Warbler, Lincoln’s Sparrow, and White-throated Sparrow are common associates of muskegs containing dense ground and shrub cover (Niemi and Hanowski 1992, Falls and Kopachena 1994, Ammon 1995, USDA 2002). Open bogs also provide winter foraging habitat for irruptive northern boreal and/or arctic owls including the Arctic subspecies of the Great Horned, Snowy, Great Gray, and Northern Hawk owls, and occasionally the very rare Boreal Owl.

Priority Birds

Species Status Habitat and/or Special Habitat Features
Trumpeter Swan b, m Uncommon, local breeder in open bog/muskeg and associated shallow waters.
American Black Duck b Local breeder in large tracts of open bog and muskeg adjacent to brood habitat.
American Bittern b Local breeder in large tracts of open bog.
Northern Harrier b, m Local breeder in large tracts of open bog.
Spruce Grouse b, m, w Local breeder in muskeg and spruce forests.
Sharp-tailed Grouse b Nests under black spruce branches and forages in muskeg.
Yellow Rail b Requires a dense sedge component within an open bog.
Solitary Sandpiper m Found locally along edges of small ponds.
Short-eared Owl b, m, w Uncommon migrant or wintering bird in open bog when small mammals are abundant.
Black-backed Woodpecker b Requires dead or dying trees for foraging.
Olive-sided Flycatcher b, m, w Uses tall snags for singing and foraging perch.
Boreal Chickadee b, m, w Uncommon breeder in muskegs with snags.
Sedge Wren B Requires a dense sedge component within an open bog.
Golden-winged Warbler b Uses open bogs with a shrub component.
Nashville Warbler B Common breeder in muskegs with high densities of spruce.
Connecticut Warbler b Nests in muskegs with patches of tall spruce and along muskeg/black spruce forest transitions.
Common Yellowthroat B Common breeder in open bogs with dense vegetation.
Clay-colored Sparrow b Uses open bogs with a shrub component.
Henslow’s Sparrow b Found locally in grass/sedge-dominated areas in central Wisconsin.
Le Conte’s Sparrow b Requires a dense sedge component within an open bog.
Swamp Sparrow B Prefers areas with shallow standing water.
White-throated Sparrow B Common breeder in muskegs.
Bobolink b Requires a dense sedge component within an open bog.
Purple Finch b Nests in muskegs with patches of tall spruce and along muskeg/black spruce forest transitions.


Stay tuned……. will incorporate habitat acreage objectives from Upper Mississippi River and Great Lakes Region Joint Venture Implementation Plan.

Management Recommendations

Landscape-level Recommendations

  1. Protect tracts of undisturbed peatlands >40 ha, especially for area-sensitive species like Northern Harrier, Yellow Rail, Short-eared Owl, American Bittern, and Sharp-tailed Grouse (Sample and Mossman 1997, Dechant et al. 2003a, Dechant et al. 2003b).
  2. Where applicable, maintain open bogs in conjunction with other aquatic habitats to protect hydrological function and provide for a diverse suite of species (WDNR 2005).
  3. Maintain wetland function and biodiversity by minimizing impervious surfaces, limiting development, and reducing soil loss and nutrient delivery within watersheds.

Site-level Recommendations

  1. Avoid habitat conversion by properly managing water levels within peatlands (i.e., avoid permanent flooding or drainage; WDNR 2005).
  2. Manage and promote conifers in and around large muskegs to support conifer-dependent bird species which utilize both upland and lowland coniferous forests.
  3. Use prescribed fire or mechanical treatments on a periodic basis to prevent invasion of woody vegetation in open bog habitats (WDNR 2005). 
  4. When restoring disturbed sites, introduce native bog flora to expedite native plant colonization and increase plant diversity.
  5. Monitor restored peatlands to assess their progression towards planned objectives and provide feedback for future efforts.

Ecological Opportunities

Ecological Landscape Opportunity Management Recommendations
Central Sand Plains Major All
North Central Forest Major All
Northern Highland Major All
Northwest Lowlands Major All
Northwest Sands Major All
Superior Coastal Plain Major All
Central Sand Hills Important 1,2,3,4,6,7,8
Northeast Sands Important All
Forest Transition Important All
Central Lake Michigan Coastal Present 1,2,3,4,6,7,8
Northern Lake Michigan Coastal Present All

Research Needs

  1. Implement a marshbird monitoring program to adequately measure abundance, distribution, population status, and habitat use of key species within open bogs and muskegs.
  2. Identify peatlands in need of protection, restoration, and/or management within all ecological landscapes in which they occur.
  3. Research the interrelationships of peatlands and other aquatic and terrestrial habitats.
  4. Investigate the effects of cranberry farming, commercial mossing, and other human activities on nesting peatland birds and their habitats in Wisconsin.
  5. Establish performance measures for peatland restorations and identify the length of time required to completely restore wetland functions and values.
  6. Monitor peatland restoration and enhancement activities to assess their wildlife value and adaptively refine management activities.  


Key Sites

Key Partners

Funding Sources

Information Sources


Contact Information

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

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