Wildlife Habitat Management Institute

Cropped Wetlands and Wildlife

May 2005 Fish and Wildlife Habitat Management Leaflet Number 32

Introduction

Wetlands are areas where water covers the soil or is 

present at or near the surface of the soil for at least 

part of the year. The saturated conditions in wetlands 

favor the growth of specially adapted plants, called 

hydrophytes, and the development of anaerobic (low 

oxygen) soils, called hydric soils. Historically, wetlands were not widely recognized as valuable or appreciated, and they were readily drained for agriculture and other land uses. In colonial times, there were 

215 million acres of functioning wetlands in the continental United States. Today, less than half (98 million acres) remain. About 87 percent of wetland losses have resulted from agricultural activities. More 

recently, however, the enormous importance of wetlands has been recognized. Wetlands provide many 

ecological, social, and economic benefits such as 

wildlife habitat, flood control, and hunting and fishing 

opportunities.

Some wetlands are wet only during parts of the year, 

such as the spring or fall, and may be dry during the 

summer. These are known as seasonal or temporary 

wetlands. Many temporary wetlands occur in cultivated fields and are tilled and planted when conditions 

allow. These cropped wetlands may be considered 

nuisance spots by agricultural producers, but continue to provide significant ecological and economic benefits. Ecological benefits are derived from these 

sites not because they are cropped, but from their 

ability to continue to provide important wetland functions. In most years, these wetlands are dry enough 

to farm. Their soils hold moisture longer than welldrained soils and are extremely productive in dry seasons. This leaflet focuses on cropped wetlands, where 

they are found, and the particular benefits they provide to wildlife. A few economic benefits of cropped 

wetlands are also discussed. Landowner assistance 

programs to help maintain or restore cropped wetlands are presented.

NRCS

Cropped wetlands may retain wildlife value.

Distribution

Cropped wetlands are most prevalent in four distinct regions in North America. They are the Prairie 

Pothole Region, Nebraska’s Rainwater Basin and 

Sandhills, the Playa Lakes Region, and the Mississippi 

Alluvial Valley.

Prairie Pothole Region

The Prairie Pothole Region is about 300,000 square 

miles in size and covers parts of South and North 

Dakota, Minnesota, Montana, Iowa, Manitoba, 

Saskatchewan, and Alberta. The region is characterized by an abundance of small wetlands situated in 

shallow depressions that were created by glaciers several thousand years ago. The region supports more 

than 200 species of migratory birds and produces 

more than 50 percent of the ducks in North America, 

even though it accounts for only 10 percent of the entire North American duck breeding area. Many of the 

potholes have been drained to produce agricultural crops. The region once contained 20 million acres 

of wetlands, of which 5.3 million acres remain. More 

than 78 percent of the remaining wetlands are smaller 

than 1 acre in size.
Cropped Wetlands and Wildlife

NRCS

A cropped wetland in the Prairie Pothole Region

Rainwater Basin and Sandhills

The Rainwater Basin and Sandhills cover 4,200 

square miles south of the Platte River in south central 

Nebraska and features wetlands in depressions underlain by clay. Large numbers of waterfowl use this 

area during spring migration to rest and prepare for 

the long trip northward. Some 2.5 million ducks move 

through this area each spring. Approximately 90 percent of the wetlands in this region have been drained 

and irrigated for corn production. 

Playa Lakes Region

The playa lakes are shallow, circular depressions that 

are seasonally or semi-permanently flooded by rain 

water and snow melt in the Texas panhandle, western Oklahoma, eastern New Mexico, southwestern 

Kansas, and southeastern Colorado. The region provides extremely valuable wintering grounds for migratory birds. During winters with high precipitation, the 

playas are used by up to one million ducks, 500,000 

geese, and more than 350,000 sandhill cranes. At least 

70 percent of playas 10 acres or larger have been hydrologically altered by irrigation development.

Mississippi Alluvial Valley

The Mississippi Alluvial Valley covers portions of 

southern Illinois, southwestern Missouri, western 

Tennessee, western Kentucky, eastern Arkansas, 

western Mississippi, and eastern Louisiana. Here, 

more than 85 percent of the original 24 million acres 

of seasonally flooded bottomland hardwood forest 

have been converted to cropland for soybean, rice, 

corn, and cotton production. Cropped wetlands in 

this area provide wintering grounds to 1.5 million mallard ducks (almost 70 percent of all mallards in North 

America) and numerous other water birds.

Wildlife benefits

Small wetlands, many of which are cropped, play an 

important role in the life cycles of many waterfowl. 

In the northern breeding grounds, cropped wetlands 

are typically small basins that thaw earlier than other wetlands and hold water during the early spring, 

which provides migrating birds with food and breeding habitat not found on semi-permanent and permanent wetland types. Studies show that temporary and 

seasonal wetlands, including cropped wetlands, comprise about 35 percent of the wetland area in North 

Dakota, but support 57 percent of the breeding waterfowl population. The loss of these wetlands would 

likely translate into a 20 to 60 percent loss of production for mallard, gadwall, blue-winged teal, and pintail 

populations.

During their migratory journey northward, dabbling 

ducks stop to rest and feed at various wetlands along 

their route. Dabbling ducks (those that ordinarily 

feed in shallow water on or near the surface by submerging part of their body, leaving their tail sticking straight up) include mallards, blue-winged teal, 

gadwall, and northern pintail. The long migration requires large amounts of energy, and the ducks must 

accumulate fat and nutrient reserves for the upcoming egg-laying season. Cropped wetlands provide nutrient-rich water (snow-melt run-off, spring rain), as 

well as protein-rich invertebrates (fairy shrimp, midge 

larvae, snails, etc.), seeds, and tubers, which satisfy 

the high-energy demand of the ducks during this time. 

Invertebrates are more abundant and more easily obtained in temporary wetlands than in deeper, more 

permanent wetlands.

A little history

The Wetland Conservation or Swampbuster provision of the 1985 Farm Bill, as amended, requires agricultural producers to protect the wetlands on the 

farms they own or operate if they want to remain 

eligible for USDA farm program benefits. Wetlands 

that were drained and cropped before December 

23, 1985, but no longer exhibit the characteristics of a wetland are called prior converted croplands. Wetlands that were drained and cropped 

before December 23, 1985, but that continue to exhibit the characteristics of a wetland are called 

farmed wetlands. Farmed wetlands are subject to 

the Swampbuster provision; prior converted croplands are not.

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Cropped Wetlands and Wildlife

ity of invertebrates and vegetation, but birds still benefit from their presence on the landscape. Cropped 

wetlands still offer more biological value than drained 

wetlands. During drought years, these areas are usually not used by waterfowl and other migratory birds, 

and may provide farmers with the only productive areas on the farm because of the retained soil moisture.

Other benefits

In addition to serving as feeding and breeding grounds 

for migratory birds, cropped wetlands provide benefits to farmers, including protecting and improving 

water quality, storing floodwaters, and allowing for 

ground water recharge, which contributes to base 

flow to surface water systems during dry periods.

Cropped wetlands protect and improve water quality 

by removing silt and excess nutrients from field runoff. The low-oxygen wetland soils transform excess 

nitrogen into a harmless gas that enters the atmosphere. Studies show that a 1-acre wetland can effectively purify the nitrate runoff from approximately 100 

acres of cropland. Excess phosphorus and other pollutants are stored in the soil. 

Wetlands, including those that are cropped, possess 

valuable flood control properties. They act like natural sponges that absorb surface water, rain, snowmelt, 

groundwater, and floodwaters, reducing flood frequency and peak flood levels on adjacent and downstream land. Over time, retained floodwaters are slowly released back into streams, rivers, the atmosphere, 

NRCS

U. S. Fish and Wildlife Service

Small cropped wetlands provide space for mallard ducks to 

form pair bonds in isolation from other ducks.

Cropped wetlands also offer crucial habitat for waterfowl pair formation in the early spring. A 0.1-acre 

wetland will lead to the production of as many ducks 

as a 1-acre wetland because waterfowl form mating 

pairs as a direct result of territorial behavior, which 

is accommodated by small isolated wetlands, rather than when crowded on large wetland bodies. Thus, 

100 1-acre wetlands are many times more valuable 

than a single 100-acre wetland. The area of wetlands 

in the Prairie Pothole Region that are less than a quarter acre in size totals over 167,000 acres. These small 

wetlands may seem unimportant to some, but collectively represent significant waterfowl courtship habitat. Studies in the Prairie Pothole Region have also 

shown that killdeer, marbled godwits, and savannah 

sparrows achieve higher breeding densities on temporary and seasonal wetlands than on any other wetland type. 

Many cropped wetlands can be farmed in most years, 

although spring tillage and planting operations may be 

delayed. Plowing and disking may affect the availabil- Aerial view of cropland interspersed with wetlands in 

South Dakota

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Cropped Wetlands and Wildlife

or groundwater. This process allows for ground water 

recharge, which helps maintain stream flows during 

dry periods. A study in North Dakota found that small 

wetlands could retain 72 percent of the runoff from 

a 2-year storm and 41 percent of that from a 100-year 

flood, thus providing substantial benefits at virtually 

no cost. Even a small, 1-acre wetland can hold 330,000 

gallons of water that is prevented from going downstream and causing flood damage.

Restoration of cropped wetlands

While cropped wetlands retain valuable wildlife benefits, these benefits may be enhanced by restoring 

the wetlands to their original state. If these wetlands 

are left uncropped and drainage ditches or tiles are 

plugged when necessary, natural wetland vegetation 

will return. Once restored, the wetlands established 

will likely have greater ecological and, in some cases, 

economic values. A number of voluntary assistance 

programs (table 1) are available to landowners wishing to restore or preserve wetlands on their property.

Table 1 Technical and finanacial assistance to restore or preserve wetlands

Program Land eligibility Type of assistance Contact

Wetlands Reserve 

Program (WRP)

Conservation 

Reserve Program 

(CRP)

Farmable Wetlands 

Program 

U. S. Fish and 

Wildlife Service 

Easements

Partners for 

Fish and Wildlife 

Program (PFW)

Previously degraded 

wetland and adjacent 

upland buffer, with 

limited amount of 

natural wetland and existing or restorable riparian areas.

Highly erodible land, 

wetland, and certain 

other lands with cropping history, streamside areas in pasture 

land.

Farmable wetlands and 

associated buffers. 

Areas that enable producers to continue to 

crop wetland basins 

while preventing additional drainage. 

Most degraded fish 

and/or wildlife habitat.

75% cost-share for wetland restoration 

under 10-year contracts and 30-year 

easements, and 100% cost-share on restoration under permanent easements. 

Payments for purchase of 30-year or 

permanent conservation easements.

50% cost-share for establishing permanent cover and conservation practices, and annual rental payments for land 

enrolled in 10- to 15-year contracts. 

Additional financial incentives for some 

practices.

50% cost-share for establishing permanent cover and conservation practices, and annual rental payments for land 

enrolled in 10- to 15-year contracts. 

Additional financial incentives for some 

practices.

The U.S. Fish and Wildlife Service purchases easements from willing landowners.

Up to 100% financial and technical assistance to restore wildlife habitat under a minimum 10-year cooperative 

agreement.

NRCS state or local 

office

NRCS or FSA state or 

local office

NRCS or FSA state or 

local office

U.S. Fish and Wildlife 

Service local office

U.S. Fish and Wildlife 

Service local office

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Cropped Wetlands and Wildlife

References

On-line sources

Chesapeak Bay Program Office. 2003. Wetlands: General Info. http://www.chesapeakbay.net/wetlds1.

htm [Accessed 14 June 2004].

Iowa State University College of Agriculture. n.d. 

IWRACP About Wetlands. http://www.ag.iastate.

edu/centers/iawetlands/About.html [Accessed 24 

November 2004].

U.S. Army Corps of Engineers Sacramento District. 

2000. Wetlands and Agriculture: Section 404 of 

the Clean Water Act and Swampbuster in the 

Food Security Act. http://www.spk.usace.army.

mil/cespk-co/regulatory/SB.html [Accessed 9 

June 2004].

U.S. Environmental Protection Agency. 2003. Wetlands and People. http://www.epa.gov/owow/wetlands/vital/people.html [Accessed 23 November 

2004].

U.S. Environmental Protection Agency. 2003. What are 

wetlands? http://www.epa.gov/owow/wetlands/vital/what.html [Accessed 23 November 2004].

U.S. Environmental Protection Agency. 2002. Functions and Values of Wetlands. http://www.epa.

gov/owow/wetlands/facts/fun_val.pdf.

U.S. Geological Survey, Northern Prairie Wildlife Research Center. 1994. Wildlife Habitat Management 

on the Northern Prairie Landscape. http://www.

npwrc.usgs.gov/resource/habitat/whabmgt/whabmgt.htm [Accessed 24 November 2004].

Printed sources

————. 1996. Oases for wildlife: small and farmed 

wetlands. National Audubon Society, Washington, 

DC.

Anderson, J.K., R.W. Spain, L.D. McKinney, and A. 

Sansom. 2000. Wetlands assistance guide to landowners. Texas Parks and Wildlife, Austin, TX.

Berry, C.R., Jr. and D.G. Buechler. 1993. Wetlands in 

the Northern Great Plains: A guide to values and 

management. U.S. Fish and Wildlife Service and 

the Agricultural Extension Service, South Dakota 

State University, Brookings, SD.

Kantrud, H.A., and R.E. Stewart. 1984. Ecological distribution and crude density of breeding birds on 

prairie wetlands. Journal of Wildlife Management 

48:426-437.

Kantrud, H.A., and R.E. Stewart. 1977. Use of natural 

basin wetlands by breeding waterfowl in North 

Dakota. Journal of Wildlife Management 41:243-

253.

Krapu, G.L., and G.A. Swanson. 1975. Some nutritional 

aspects of reproduction in prairie nesting pintails. 

Journal of Wildlife Management 39:156-162.

Steward, R.E., and H.A. Kantrud. 1973. Ecological 

distribution of breeding waterfowl population in 

North Dakota. Journal of Wildlife Management 

37:39-50.

Steward, R.E., and H.A. Kantrud. 1974. Breeding waterfowl populations in the Prairie Pothole Region 

of North Dakota. Condor 76(1):70-79. 

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Cropped Wetlands and Wildlife

Natural Resources Conservation Wildlife Habitat Council

Service 8737 Colesville Road, Suite 800

Silver Spring, Maryland 20910

(301) 588-8994

Check your local telephone directory for a field 

office near you.

The mission of the Wildlife Habitat Council is to 

The Natural Resources Conservation Service increase the amount of quality wildlife habitat

provides leadership in a partnership effort to on corporate, private, and public land. WHC enhelp people conserve, maintain, and improve our gages corporations, public agencies, and private,

natural resources and environment. non-profit organizations on a voluntary basis for 

the recovery, development, and preservation of 

wildlife habitat worldwide.

www.nrcs.usda.gov www.wildlifehc.org

Primary Author: Raissa Marks, Wildlife Habitat Council. Drafts reviewed by: Rob Pauline, Wildlife Habitat 

Council; Charlie Rewa, Natural Resources Conservation Service; Lloyd Jones, U.S. Fish and Wildlife Service; 

Ron Reynolds, U.S. Fish and Wildlife Service; and Kevin Willis, U.S. Fish and Wildlife Service.

The United States Department of Agriculture (USDA) prohibits discrimination in all its programs and activities 

on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, 

and marital or familial status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternate means for communication of program information (Braille, large print, audiotape, etc.) should 

contact the USDA’s TARGET Center at (202) 720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Office of Civil Rights, Room 326W, Whitten Building, 14th 

and Independence Avenue, SW, Washington, DC 20250-9410, or call (202) 720-5964 (voice or TDD). USDA is an 

equal opportunity provider and employer.

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