Grassland Birds | Mass Audubon

Register Log In

Agricultural Grasslands

Photo by Huston Westover

Small Grasslands

Managing Small Grasslands for Grassland Birds

Introduction
Value of Small Grasslands to Wildlife
Mowing Small Hayfields
Grazing Small Pastures
Burning Small Pastures
Grassland Restoration
Enhancing Public Interest in Grassland Conservation

Introduction

Grasslands in the Northeast have provided home and sanctuary to grassland birds and other wildlife for many hundreds of years. In hayfields, pastures, and natural grasslands, birds such as bobolinks and eastern meadowlarks have raised their young, hunted for food, and returned each spring to continue this cycle. We are rapidly losing these and other grassland birds that were once a common and integral part of our countryside. As land use and agricultural practices have changed dramatically since the turn of the century, remaining grasslands have become smaller and isolated. With proper management, these small grasslands provide important habitat for some species of grassland birds.

The following information addresses management issues on small grasslands, generally ranging in size from 10 to 75 acres, that are not in active agricultural use. These include areas such as conservation or recreation lands, small landfills, corporate parks, and small airports.

Value of Small Grasslands to Wildlife

Male Northern Harrier
Photo by Roger S. Everett

Farmland fragmentation has caused the remaining grasslands to become small and isolated. These smaller patches are not suitable for all species of grassland birds, such as upland sandpipers that require at least 100 acres of continuous grassland habitat for breeding. However, there are other grassland birds, such as bobolinks, eastern meadowlarks, and savannah sparrows, that rely on these small areas throughout the year.

Bobolinks and eastern meadowlarks build nests, raise young, and forage in hayfields, meadows, and pastures during the summer.

Many birds of prey, such as American kestrels, northern harriers, and short-eared owls, rely on grasslands for hunting small mammals during summer or winter.

Waterfowl and shorebirds sometimes feed in flooded portions of fields during migration.

Grasslands also provide habitat to a variety of other wildlife, including mammals and many butterflies. Small mammals that inhabit fields, such as meadow voles and meadow jumping mice, are an important food source for many birds of prey. Larger mammals, such as white-tailed deer and red foxes, regularly visit grasslands for feeding. Butterflies, such as tiger swallowtails, monarchs, and fritillaries, can be found in fields feeding on wildflower nectar.

Mowing Small Hayfieds (10 - 75 acres)

Hayfields support a rich diversity of grasses, wildflowers, and invertebrates that are important for breeding grassland birds. Old hayfields, not replanted for at least eight years, are favored by some birds (particularly bobolinks) because of the developed ground cover and a greater variety of grasses and other plants. Mow every one to three years to maintain fields in grasses and prevent growth of woody vegetation. Timing of mowing is crucial to the survival of nesting grassland birds. Early mowing in June and frequent mowing destroy nests and young. Therefore, mowing after August 1 is recommended if increasing grassland bird habitat is a management goal.

Recommendations
Avoid mowing areas with ground-nesting birds before August 1. Early cutting usually destroys ground nests. It is common to see young birds in the fields by late June, but cutting should be avoided because some species, such as savannah sparrows and eastern meadowlarks, raise a second brood later in the season, and the young fledge in late July.

Be aware of where grassland birds are nesting in fields. If mowing is essential prior to August 1 (such as in fields leased to farmers for hay), try to avoid areas where birds are frequently seen or to leave small patches such as edges or strips unmowed as nesting areas. Even when young birds appear to have left the nest, small unmowed patches are still needed to provide cover and feeding areas for the remainder of the summer until they migrate south.

Limit mowing to every one to three years in fields not harvested for high-quality hay. It is not necessary to mow every year for grassland birds. Not mowing a field one year or delaying mowing until late August will allow development of late-blooming wildflowers and butterflies.

Maintain some areas of fields with patches of bare ground. Killdeers and horned larks, for example, require patches of bare ground for nesting and feeding. This can simply be in areas where grass growth is poor due to soil conditions, or in small areas intensively grazed. Bare ground can also be exposed by removing hay from fields where thatch (compressed dead grass) becomes thicker than two inches.

Choose fields that are not used for hay production for wildlife habitat. Mowing high-quality hayfields in early June will discourage birds from nesting in those areas. Birds that do attempt to nest in these fields will probably fail due to mowing activities. In time, birds are not likely to return to fields where their nests were destroyed. However, if adjacent unmowed fields are available, birds can shift from high-production hayfields to those areas and renest.

Use conservative mowing practices where possible. These may include practices such as raising mower blades to six inches or more (may prevent the destruction of some nests and young in early mowing); avoiding night mowing because this often kills or injures roosting birds and young; using flushing bars on haying equipment to move birds hiding in the grass.

Manage multiple contiguous fields for conservation. Four adjacent fields are better than four isolated fields. Multiple adjacent small fields can provide the "look" of a large grassland, especially if hedgerows are removed and planted in grasses. This continuous landscape is necessary for some of the region's rarer grassland birds, such as the grasshopper sparrow and upland sandpiper, which require large grasslands. Multiple contiguous fields can be managed through rotational mowing and/or burning to provide a mosaic of grassland types and, therefore, can attract a greater diversity and abundance of grassland birds.

Grazing Small Pastures (10 - 75 acres)

Photo by Peter D. Vickery

Grazing can benefit grassland wildlife by creating a mosaic of grass heights and structure. Many birds respond favorably to limited grazing, including killdeers and meadowlarks. However, intensive grazing leads to a loss of plant diversity and cover for wildlife. In the Northeast, the majority of grazed pastures are small and intensively grazed during the summer months, making them unsuitable for most nesting birds.

Recommendations
In grazed pastures with nesting birds, keep approximately 40 percent of the vegetation cover at a minimum height of 8 to 12 inches or at "knee height," with scattered forbs until August 1. This can be achieved by rotating grazing animals through several fields during the growing season. Keeping some areas ungrazed during the nesting season usually improves nest success.

Avoid overgrazing fields. Overgrazing creates excessive bare ground, which can cause erosion, reduce plant and invertebrate diversity, and lead to trampling of bird nests.

Experiment with different grazing regimes in your fields to determine the intensity of grazing and rotation that works best to provide wildlife habitat. This will vary from site to site, depending on the type of vegetation and the soil and moisture conditions.

Burning Large Grasslands

Burning reduces buildup of dead vegetation, adds nutrients to the soil, rejuvenates plant growth, and helps prevent the spread of woody vegetation. Hayfields that develop a thick layer of thatch are usually not used by nesting birds because they cannot effectively run on the ground to escape predators or forage for food. Although burning is not always feasible on small grasslands, when possible it can benefit grassland bird populations within one or two years following a burn.

Recommendations
Burning every two to six years provides the best habitat for birds nesting in small grasslands. If possible, provide adjacent unburned grassland habitat for nesting birds during the burn year.

Burning in early spring (before the arrival of birds in mid-May) is most beneficial to vegetation and nesting birds.

Careful planning is necessary before burning. Most grassland burns occur between mid-March and the end of April, after snow melt and before greening and bird nesting. The timing of the burn must also be done with consideration of relative humidity, wind conditions and direction, air temperature, and fuel conditions. Burn designs must incorporate existing firebreaks (roads, lakes, and streams), or firebreaks must be designed. Adjacent landowners should be notified prior to burning.

Contact your local fire department for guidance and permits before burning a field. "Burn bosses," individuals trained and certified in prescribed fires, from local universities or conservation organizations (see Table 4, Agencies or Organizations Specializing in Agricultural Land Management Issues for list of state Audubon/ conservation societies to contact) can be contracted to consult and manage prescribed burns.

Grassland Restoration

Photo by Huston Westover

Areas that have been neglected, invaded with woody vegetation, overgrazed, or planted with alfalfa or row crops can be restored into grasslands that will provide wetlands protection habitat for grassland birds.

Recommendations
Protection from overgrazing: Follow the above guidelines under "Mowing" and "Grazing" to restore a grassland to a more natural and diverse system and provide improved habitat for grassland birds.

Removal of woody vegetation: Field edges, particularly those dividing fields, can be removed to control invasive woody plants and create larger grasslands. Removal of woody vegetation can be achieved by a variety of means: mechanically, chemically, or by burning. Removal should be avoided during the nesting season to minimize disturbance to nesting birds. An intensive spring fire regime for several years helps kill shrubs and encourages growth of native species. Once shrub growth is retarded, burning can be reduced to a light burn every two to six years to maintain grasses. Spot treatment is often used to help remove particularly stubborn shrubs and trees. Some herbicides may be applied directly to the newly cut shrub stem. Read herbicide labels carefully and consult your local Cooperative Extension Service office for advice on use of herbicides (see Table 4, Agencies or Organizations Specializing in Agricultural Land Management Issues).

Replanting with warm-season grasses: Areas void of vegetation should be disked and plowed in the fall, and disked again in the spring and seeded with native warm-season grasses. Attention should be paid to soil type, moisture content, and slope in order to decide what grasses to plant. Providing firmly packed soil and a weed-free seedbed is necessary to successfully seed a field. After substantial growth, periodic rejuvenation, such as burning, will maintain a healthy stand of grass. Consult soils maps, available from state Natural Resources Conservation Service offices (see Table 4, Agencies or Organizations Specializing in Agricultural Land Management Issues ), to determine what types of grasses will grow best on your soil type. (See Table 3, Nurseries Specializing in Native Grasses and/or Wildflowers.)

Use of pesticides: During restoration of a site formerly in crop production, attention should be paid to former use of pesticides and herbicides. If cropland was recently treated with certain chemicals, planted grasses may not grow. Consult your local Natural Resources Conservation Service office (see Table 4, Agencies or Organizations Specializing in Agricultural Land Management Issues) to determine the best way to proceed.

Planting fields in warm-season grasses, in addition to the more commonly planted cool-season grasses, can benefit both the farmer and wildlife. (See Table 5, Warm-Season vs. Cool-Season Grasses.)

Enhancing Public Interest in Grassland Conservation

The following suggestions can help local communities become involved in the protection of grassland habitats.

Volunteers: Use volunteers to monitor grassland bird populations. Observers can locate fields containing breeding birds, where they are breeding, and when they have successfully fledged young. If haying a field is contracted to a farmer, these observations can help determine a mowing schedule that will protect grassland birds. Local bird clubs or conservation organizations can provide knowledgeable volunteers (see Table 4, Agencies or Organizations Specializing in Agricultural Land Management Issues for list of local Audubon societies).

Scouts/school groups: Use scouts or school groups to build nest boxes for bluebirds and swallows that can be placed along field edges. Volunteers can monitor these boxes for bird use and breeding success.

Contact the North American Bluebird Society for guidelines on box designs.

North American Bluebird Society
P. O. Box 6295
Silver Spring, MD 20916-6295
Phone: (301) 384-2798

Education: Make grasslands visible to local residents. Displays showing birds, butterflies, and mammals that may be observed in a field and observation areas can increase public awareness and appreciation of protected grassland habitats. Protect nesting areas from human disturbance by placing "Grassland Bird Nesting Area" signs in fields and providing mowed paths along field edges for public use.

By following these suggestions, grasslands owned by land trusts, conservation organizations, and individuals can provide a diverse and healthy grassland system for wildlife and the enjoyment of the public visiting these areas.