Fallow Field

Habitat Description

Habitat Crosswalk


The Fallow Field community consists of crop fields that have not been planted in the last one to three seasons. Fields are typically plowed at least once a year and thus have variable amounts of bare soil, plant litter, and crop debris (Herkert et al. 1996, Sample and Mossman 1997, Kaufman et al. 2000). Annual plowing also maintains early-successional plant species that are adapted to disturbed conditions, such as weeds. Weed communities can tolerate a variety of soil and moisture conditions but their composition often is influenced by the crop last present (Curtis 1971). For example, common ragweed is a common pioneer species in recently abandoned small grain fields whereas black mustard often is associated with abandoned cornfields (Curtis 1971). If a field is fallowed for several years, however, its weed community becomes less distinct as weeds from surrounding areas invade (Curtis 1971, Sample and Mossman 1997). These tend to be generalist species with broad distributions, such as Canada thistle, quackgrass, pricky lettuce, common dandelion, fleabane, spotted knapweed, leafy spurge, and Queen Anne’s-lace. 

Historical and Present-day Context and Distribution

During the nineteenth century, diverse prairie communities in Wisconsin were largely eliminated in favor of small grains, grass hay, alfalfa, pastures, and orchards. Although these changes destroyed or significantly altered most native grasslands, the landscape remained largely rural with small farmsteads interspersed with idled or undeveloped lands. Many birds adapted to these changes and used the diversified, small-scale farms as surrogate grassland habitats (Warner 1994). By the mid-twentieth century, however, farming systems became more specialized and the agricultural landscape became more simplified as a consequence. Today, Fallow Field and many non-crop habitats have been eliminated in order to plant larger sections of monotypic crops (Warner 1994, Best et al. 1995, Sample et al. 2003, WDNR 2005). The abundance and diversity of weed flora has decreased as crop management techniques have become more efficient. In particular, increases in both the diversity and amount of chemicals used for weed control have likely affected both the plant and animal species composition of Fallow Field.

Natural Disturbances and Threats

Fallow Field experiences some of the same disturbances as active cropland. Fallow fields often are plowed on an annual basis to limit growth of undesirable herbaceous plants and prevent secondary succession of woody plants. A variety of herbicides also are used to control weed communities, which in turn can have indirect impacts on many non-target species (see Overall Importance of Habitat for Birds). Renewed interest in corn ethanol and other market factors have led to high corn prices, creating pressure to put fallow fields back into production (Murray and Best 2003, Roth et al. 2005, Bies 2006). Urban sprawl is another significant threat. As housing developments replace farmland throughout the state, surrogate grasslands such as Fallow Field become increasingly fragmented and less suitable as wildlife habitats.

Related WBCI Habitats: Idle Warm-season Grasses and Forbs, Idle Cool-season Grasses and Forbs, Small Grains, Row Crop.

Overall Importance of Habitat for Birds

Fallow fields are important to grassland bird species that require a higher forb component and lower litter layer. Mechanical and chemical weed control measures create areas of bare ground within fallow fields and thus attract bird species such as Horned Lark, Vesper Sparrow, and other sparse-cover specialists (Sample and Mossman 1997). As the intensity of management declines, a range of vegetative conditions is possible. Fields with a moderate cover of weeds may provide suitable nesting and foraging habitat for Northern Bobwhite, Savannah Sparrow, Grasshopper Sparrow, Dickcissel, Bobolink, Eastern Meadowlark, and Western Meadowlark. If the weed community develops into a tall, dense stand, Common Yellowthroat and Red-winged Blackbird may occur. Plant composition affects birds use, however, since fields dominated by forbs may not provide suitable nesting habitat for most grassland birds (Sample and Mossman 1997). 

Although weed species vary considerably in their wildlife value, many offer important ecological functions within intensively managed agricultural areas. Herbicides reduce or eliminate weed communities on fallow fields and thus alter the food and cover resources available to birds. Some weeds are host plants for beneficial insects, which in turn are eaten by birds. Weed seeds support rodent populations that are important to Northern Harrier, Red-tailed Hawk, Short-eared Owl, and other raptors that prey on small mammals (Kaufman et al. 2000). Granivorous birds such as sparrows and finches also rely on weed seeds to meet their energy demands, especially during the winter months (Marshall et al. 2003). Thus, effects of herbicides extend beyond the weed community to impact the productivity, survival, and distribution of species that rely on weeds during some part of their annual cycle (Best et al. 1995, Pollock 2001, Marshall et al. 2003, Boatman et al. 2004, Krapu et al. 2004). Wherever possible, farmers should minimize use of herbicides and choose products that are less toxic to non-target species (Boatman et al. 2004).

Priority Birds

Species Status Habitat and/or Special Habitat Features
Mallard b, f Seasonally flooded fallow fields can offer high-quality foraging opportunities.
Sharp-tailed Grouse f May forage in fallow fields embedded within a large, grassland-dominated area.
Greater Prairie-Chicken f May forage in fallow fields surrounding core protected areas in central Wisconsin.
Northern Bobwhite b, w Requires brushy areas adjacent to fallow fields.
Northern Harrier b, m May occur in fallow fields embedded within a large, grassland-dominated area.
Upland Sandpiper b, m Occurs in high-grass landscapes with some drier ridges and hummocks.
Barn Owl f Very rare resident in southern and central Wisconsin.
Short-eared Owl f May forage in fallow fields embedded within a large, grassland-dominated area.
Northern Flicker f  
Loggerhead Shrike f Very rare in Wisconsin.
Barn Swallow f  
Brown Thrasher b, f Requires scattered patches of shrubs.
Common Yellowthroat b, m Prefers tall, dense herbaceous cover and/or a shrub component.
Clay-colored Sparrow b, m Requires scattered shrubs.
Vesper Sparrow B, M Prefers areas with short, sparse vegetation and some bare ground.
Lark Sparrow b, m Prefers areas with some bare ground.
Grasshopper Sparrow B, M Prefers relatively short, patchy vegetation.
Dickcissel b, m Prefers sites with a thick-stemmed forb component.
Bobolink b, m  
Eastern Meadowlark b, m  
Western Meadowlark b, m Prefers relatively short vegetation and <5% woody cover.


Management Recommendations

Landscape-level Recommendations

  1. Consider incorporating a fallow field rotation into public lands, especially areas managed for Mourning Dove hunting.
  2. Support state and federal programs that manage, enhance, or restore grassland habitats on private lands. Develop cooperative agreements with private landowners to prevent habitat fragmentation and conversion in areas critical for grassland bird conservation.
  3. Partner with the agricultural community to ensure rural working landscapes with high amounts of open space suitable for birds and other wildlife.
  4. Determine what scale of landscape management is possible in an area: medium (400-2,000 hectares) or large (>4,000 hectares). Consider developing a grassland Bird Conservation Area in appropriate landscapes (see Fitzgerald and Pashley 2000).

Site-level Recommendations

  1. Reduce the use of herbicides and choose products that are less toxic to non-target species (Boatman et al. 2004).
  2. Delay plowing of fallow fields until August 1 to protect late-nesting species and fledglings.
  3. Remove linear woody features such as hedgerows and woody fencelines as well as woodlots to improve site suitability for obligate grassland birds. Low density, scattered shrubs are acceptable and even required by some grassland birds such as Willow Flycatcher, Bell’s Vireo, and Brown Thrasher (Sample et al. 2003, WDNR 2005, Kost et al. 2007).

Ecological Opportunities

Ecological Landscape Opportunity Management Recommendations
Southwest Savanna Important All
Western Coulee and Ridges Important All
Western Prairie Important All
Central Lake Michigan Coastal Present All
Central Sand Hills Present All
Central Sand Plains Present All
North Central Forest Present All
Northeast Sands Present All
Northern Highland Present All
Northern Lake Michigan Coastal Present All
Northwest Lowlands Present All
Northwest Sands Present All
Forest Transition Present All
Southern Lake Michigan Coastal Present All
Superior Coastal Plain Present All

Research Needs


Key Sites

Fallow fields occurring on private lands can complement adjacent public lands by increasing overall grassland heterogeneity and size. Listed below are native grassland sites that might benefit from nearby fallow field habitats:

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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