Northern Prairie Wildlife Research Center
Definitions of Grasslands and Grassland Birds
We define Wisconsin grasslands broadly to include all native grasslands, from sedge meadows and open bogs to prairies, savannas, and barrens communities. We also include surrogate prairie grasslands (hereafter "surrogate grasslands"), which represent the vast majority of grassland habitat in the state. Surrogate grasslands are habitats that are similar to and replace the former prairie grasslands chat historically occurred in Wisconsin. Surrogate grasslands include agricultural habitats such as hayfields, small grains (oats, wheat, and barley), row crops (corn, soybeans, and potatoes), fallow fields, old fields, pastures, and set-aside fields. Examples of other surrogate grasslands include young conifer plantations, orchards, parks, golf courses, airports, cut-over or burned-over forests, and mossed bogs (bogs from which sphagnum moss has been removed commercially). Surrogate grasslands also include other idle grasslands, such as those on public lands managed for wildlife. Usually, idle grasslands are composed of non-native grasses and forbs, but they also can be plantings of one or several native species.
Some of the habitats we consider are on the wet (e.g., sedge marshes and open bogs) and woody (e.g., upland shrub and brush prairie barrens) ends of the grassland habitat continuum. They are included because they are used by grassland birds, because they include at least some elements of grassland vegetation structure, and because they represent communities that are not usually covered in management plans for other habitats, such as wetlands or forests.
We consider grassland birds to be those species that use these grassland habitats during the breeding season for courtship, nesting, foraging, rearing young, and roosting or resting. During the breeding season, 105 species regularly or occasionally use Wisconsin grasslands for at least one of these functions, representing 45% of the 233 confirmed breeding species in the state (Robbins 1991; Appendix A). Of these 105 species, 40 require grasslands or a grassland habitat setting for part of their breeding cycle, including nesting or foraging (see sidebar). These 40 species include 17 grassland obligatesspecies that require grasslands for most or all parts of their breeding cycles and who don't require non-grassland features such as trees. Also included in the list of 40 birds are some species that may not normally be thought of as grassland birds but which occur on either the wet or woody ends of the grassland habitat spectrum, such as shrub-grassland species and birds characteristic of sedge meadows or requiring open water. Sixteen additional species commonly frequent grasslands and may even nest in them but are habitat generalists or are more common in other habitats. These two groups of 40 and 16 species collectively make up the 56 species that are referred to generally in this guidebook as grassland birds. Forty-nine other species occur primarily in other habitats and less regularly in grasslands; these will not be discussed further.
Grassland Bird Habitat
Grassland bird breeding habitat must fulfill the requirements that a bird has during its nesting cycle. These requirements include suitable habitat structure (which is influenced by management history), adequate habitat size and surrounding land use, sufficient food resources, and sometimes other features including access to open water and nest cavities. High quality habitat fulfills these requirements, attracts relatively high densities of birds, and has high nest productivity. Some habitats that attract high densities of nesting birds may produce few young and therefore are not considered high quality habitat (Van Horne 1983). A more detailed discussion of grassland bird habitat requirements is found in the section, "Guidelines and Recommendations for Habitat Management."
Grassland Bird Communities
Birds with similar habitat requirements (e.g., savannah sparrow and bobolink), or whose requirements differ but are fulfilled in the same habitat type (e.g., savannah sparrow and red-headed woodpecker in open oak savannas), tend to occur together as bird communities. The composition of bird communities varies from site to site, region to region, and year to year because of differences in management history, site conditions, and precipitation patterns and because patterns of bird distribution and abundance vary across the state. As mentioned above, differences in site size, surrounding land use, and woody cover also affect the bird community composition. However, certain bird-habitat associations are fairly constant. Typical bird communities of Wisconsin grassland habitats are presented in Table 1. Some examples follow:
Grassland Bird Distribution and Abundance in Wisconsin
Grassland birds have variable patterns of distribution and abundance in Wisconsin (Table 2). Some species' breeding ranges include the entire state, while others are mainly restricted to certain natural divisions. Even for statewide species, abundance patterns typically vary from one part of the state to another. We record abundance by natural divisions, but it is important to note that species often have highly localized distributions within a natural division. For example, while Brewer's blackbird and clay-colored sparrow are listed as uncommon and rare, respectively, in the Southwestern Upland, they are largely absent from the southern three-quarters of this natural division but are locally common in the north-western part. For further information on ranges, see the sections on natural divisions; see also Robbins (1991), Price et al. (1995), or Temple and Cary (1987).
To organize our thinking and approach to grassland bird habitat management in Wisconsin we developed a management philosophy. This philosophy provides the principles that help guide the processes of developing a statewide management plan, determining management priorities, and planning and implementing management actions. The components of this philosophy include emphasizing statewide diversity of grassland birds, promoting management of viable bird populations, managing for bird communities as well as species, creating management plans that are responsive to differences in geographic scales and natural divisions, gauging the effects of management through monitoring, and encouraging public and agency education of grassland conservation issues.
Managing for Statewide Diversity
The best way to accomplish the goal of statewide diversity is to provide a broad spectrum of habitats and habitat structures in appropriate geographic locations (Ryan 1986). This includes managing for habitats that are not especially diverse either in vegetation structure or bird species richnessfor example, tracts of tall grasses and sedges with homogeneous structure, which benefit habitat specialists such as Le Conte's sparrow and yellow railor other habitats required by species that are uncommon, locally distributed, or in danger of statewide extirpation.
Diversity across the entire Midwest deserves special attention as well from both planners and managers. The conservation of some species of management concern that occur here may depend less on management in Wisconsin than management elsewhere in their ranges. At the same time, management in Wisconsin is important to species that are relatively common or secure here but are rare or declining elsewhere. Our bird-ranking scheme includes consideration of the Midwest as a whole (see "Identifying Bird Species of Management Concern and Priority Habitats for Wisconsin"). Also, the Partners in Flight program identifies priority species and habitat objectives for the Midwest and other regions (Thompson et al. 1993, Herkert et al. 1996).
Managing for Population Viability
Managing for Communities
It is almost always appropriate to focus not only on the needs of birds but also on the entire grassland ecosystem, especially including communities of plants, vertebrates, and invertebrates. Management that benefits both grassland birds and other elements of our native grassland biota should receive higher priority than activities that benefit birds alone, except perhaps certain endangered birds. For example, consider two landscapes with potential for grassland management, one of which includes a series of prairie remnants and one with no prairie remnants. The former has the greatest benefits for overall biodiversity (Henderson and Sample 1995).
Scale Issues and Regional Differences
Local management objectives should be based on similar considerations as well as on how local objectives can contribute to achieving natural division and statewide objectives. Objectives vary markedly among local areas. For example, some local areas in the Northern Highland/Lake Superior Lowland have special opportunities for maintaining extensive sedge meadows, which are required by Nelson's sharp-tailed sparrow, yellow rail, and Wilson's phalarope, while some local areas in the Southwestern Upland possess the well-drained, sandy soils needed to provide the barrens habitat suitable for lark sparrows and associated species.
Areas within natural divisions that have relatively low human populations, low land values, or large tracts owned by public or private conservation agencies may be especially appropriate for large-scale projects that benefit species requiring large areas, whereas areas with high human use and high property values may be better managed for other bird species. Some areas with very little potential for grassland bird habitat are best managed for other goals altogether. For example, it is inappropriate to manage for grassland communities in largely forested landscapes or in highly productive row crop land where any habitat created would be isolated. However, large (500 acres7 and greater) grassland restorations may be justifiable in some agricultural areas. Statewide management goals can only be attained with the cooperation and coordination of both large landowners (such as the Wisconsin DNR, U.S. Forest Service, USFWS, The Nature Conservancy, northern county forests, and forest products corporations) and smaller landowners (such as southern county forests and other county lands, other corporations, farmers, and other private landowners).
At all scales, grassland bird management should, whenever possible, consider and include private lands to ensure the success of statewide management goals, because there is not enough publicly owned land to do so.
There are some long-term monitoring programs already active in Wisconsin, of which the U.S. Department of the Interior's Breeding Bird Survey (BBS), the Wisconsin Checklist Project (Rolley 1994), and several DNR surveys (Robbins et al. 1996) are particularly useful. However, for a variety of reasons, these programs do not adequately monitor the populations of some grassland species (Robbins et al. 1996).
In addition to monitoring within Wisconsin, we need to look at trends elsewhere for species that are at the edge of their ranges in Wisconsin. For these species, long-term monitoring should also consider the status and trends of the population in the center of the range, to help distinguish range shifts and contractions in Wisconsin from overall population changes. Later in this guidebook, we provide more detail on species that are not currently adequately monitored in the state (see Table 3).
Public and Agency Education
define Wisconsin grasslands broadly to include all native grasslands;
we also include surrogate prairie grasslands, which represent the vast
majority of grassland habitats in the state, including agricultural habitats.
Surrogate grasslands are similar to and replace the former prairie grasslands
that historically occurred in Wisconsin.
birds are those species that use grassland habitats during the breeding
season for courtship, nesting, foraging, rearing young, and roosting or
overall goal of grassland bird management in Wisconsin should be to maximize
statewide diversity of grassland birds rather than just focusing on local
diversity. This means providing sufficient habitat for all grassland birds.
management should focus on bird communities as well as on species whenever
private lands in grassland management whenever possible, because there
is not enough publicly owned land to achieve statewide management goals.
|1 hectare||= 2.477 acres|
|1 square kilometer||= .386 square miles|
|1 meter||= 1.09 yards (3.279 feet)|
|1 centimeter||= .39 inches|