Many bird species are decreasing in abundance throughout their breeding ranges and are of immediate management concern. Although declines in neotropical migrant populations have received the most attention recently (Askins et al. 1990, Witham and Hunter 1992, Robbins et al 1993), populations of many short-distance migrants, permanent residents and game birds have also declined (Vance 1976, Robbins et al. 1986, Leedy 1987, Hussell et al. 1992). To reverse these trends and to ensure a future for these species, wildlife managers must develop a management plan that includes all species of concern. Time and money are limited, however, and what is good for one species may often harm another. An effective management plan for all species of concern must target not only priority species, but also priority habitats.
All species have an optimal habitat where abundance and, presumably, productivity are high. To best manage for a particular species of concern, management efforts should be concentrated in its primary habitat. Although a species may use other habitats to varying degrees, managing these habitats for the species might not make much difference in total population numbers, could be harmful to other species for which the area is primary habitat, and would not be the best use of limited funds. This is especially important for habitat specialists that only breed successfully in one habitat type.
After high priority species and their primary habitats are identified, it is important to prioritize these habitats within the larger landscape. Although the ideal management condition would be to manage all habitats to the best of our knowledge and ability, this may not be feasible. Limited funds may force managers to choose which habitats will be managed to what extent and which new land will be acquired. By prioritizing habitats according to the percentage of species of concern that use that habitat, management efforts can be concentrated on the habitats and species that need it most.
This habitat approach to managing for species of concern may be a beginning in reversing the population declines that many bird species have experienced in the past decades. For it to work, managers in each region of the country must identify their own priority species and habitats, devise the best management plan for each habitat keeping in mind all species of concern, and work together to coordinate their management plans. Partners in Flight (PIF) has begun to identify species of concern and develop conservation plans for each habitat where they occur, and this effort benefits from full participation by federal, state, and private agencies. To help accomplish this goal for the United States Fish and Wildlife Service (FWS) Region 3 part of the Mississippi Headwaters/Tallgrass Prairie (MH/TGP) ecosystem of Minnesota and Wisconsin (FWS ecosystem 22), we have:
METHODS | Study site | Habitats | Priority species | Prioritizing habitats | Management recommendations
Study site. The MH/TGP ecosystem includes the St. Croix River basin of Wisconsin and four major drainage basins of Minnesota: the Red River of the North, the Upper Mississippi River, the Minnesota River, and the St. Croix River basins (Fig. 1). This ecosystem incorporates three major biomes, tallgrass prairie, eastern deciduous forest, and northern coniferous forest, and is home to a diverse community of breeding bird species.
Habitats. We identified thirteen primary habitats in the MH/TGP ecosystem: lake, wetland, grassland, agricultural-woodland edge, shrub-sapling, lowland coniferous, lowland deciduous, young coniferous, mature coniferous, young deciduous, mature deciduous, developed, and bank-ledge (Table 1) (modified from Thompson et al. 1992). All bird species with documented breeding in at least one county within the MH/TGP ecosystem since 1970 were assigned a primary breeding habitat by using published literature and personal observation. We assigned a secondary breeding habitat to a species if it used another habitat almost as much as its primary one. Although some species use different habitats for breeding, wintering, and in migration, only breeding habitat in the MH/TGP ecosystem was considered in this report.
Priority species. We used PIF concern scores for the state of Minnesota to rank breeding species in descending order of management concern. Partners in Flight develops concern scores by assigning each species a score of 1-5 for each of seven criteria: global abundance, winter distribution, severity of threats on the wintering grounds and migration routes, severity of threats on the breeding grounds, importance of the area to the species, and population trend in that region based on the North American Breeding Bird Survey (BBS). Species are then ranked based on the sum of the seven scores. For more information on the criteria used to derive concern scores, see Hunter et al. (1992).
When Minnesota concern scores were not available, scores developed by the Prairie Pothole Joint Venture (PPJV) and PIF for the entire prairie pothole region were used. Because this region covers a large portion of the north central United States and south-central Canada, including mid- and short-grass prairies not found in the MH/TGP ecosystem, and because the prairie pothole region does not include eastern Minnesota or Wisconsin, we adjusted the PPJV-PIF importance of area scores to reflect only the MH/TGP ecosystem (Table 2). Adjusted scores are still not as accurate as Minnesota scores would be, however, because trend data from the adjusted scores still reflect the entire prairie pothole region.
After all breeding species were ranked, they were divided into six concern classes: High Priority (concern score >23), Priority (20 - 22), Concern (17 - 19), Low Concern (14 - 16), No Concern (< 13.0), and NSA (no score available). Because concern scores were unavailable for over fifty species, we provide BBS trend data for the MH/TGP ecosystem and BBS Central Region and information on a species' inclusion on federal, state, or private lists of species of concern. We considered the following lists of species of concern: the Minnesota State List of Threatened, Endangered, and Species of Special Concern, Migratory Nongame Birds of Management Concern in the United States: The 1995 List, the PPJV-PIF Grassland Species of Particular Concern, the FWS Grassland-associated Nongame Migratory Birds Species of Concern in the North Central United States (2/95), and the PIF Draft List of Species of Concern for physiographic region 28 (U.S. Northern Boreal Forest). No distinction was made between game and non-game species for ranking purposes.
BBS trend data are given for both the MH/TGP ecosystem and the BBS Central region to provide managers with a frame of reference when considering species of concern. Some species may be increasing or stable in the MH/TGP ecosystem, and therefore have a lower concern score, but they may be declining over the entire Central region. Managers may want to consider managing for these species to provide source populations for other regions. Other species may not be abundant enough or detected often enough in Minnesota to provide trend data for the MH/TGP ecosystem. Managers may want to consider these species' trend data for the entire Central region.
We caution against using BBS trend data as the sole criterion in management decisions, however, because trend data are unavailable or may be unreliable for many species (water birds, nocturnal species, wide-ranging species, species in low abundance, species detected on a small number of routes, or species that avoid roads). Some species that are not well surveyed are listed as severely declining (e.g. American bittern, Franklin's gull) or have insignificant trends. Other species, such as the red-winged blackbird and rock dove, have declining trends, but are not of great management concern because they are very abundant and wide-spread. See Robbins et al. (1986) for more information on BBS trend data.
Prioritizing habitats. Habitats were ranked in descending order of importance based on the percentage of high priority species that use each habitat as its primary habitat. Secondary habitat use was not considered in this analysis. The habitat with the greatest percentage of its species in the high priority concern class was ranked first, the habitat with the second highest percentage was ranked second, etc. When two habitats tied for percentage of species in the highest priority concern class, percentage of species in the next concern class was used.
Management recommendations. General management recommendations concerning issues that pertain to all habitat types in the MH/TGP ecosystem are given first. They are followed by specific management recommendations for each habitat type, concentrating on the highest priority habitats and the highest priority species within each habitat. Specific habitat requirements, possible limiting resources, and response to specific management practices are given for each species in the High Priority and Priority concern classes and for a few selected species in the No Score Available category. We do not discuss specific habitat needs and management practices, however, for game birds and re-introduced native species because most managers are familiar with their management requirements. Instead, we focus on the habitat requirements and natural history information for non-game species and how managers might integrate management of non- game and game species.
When possible, only studies within the north-central United States (Minnesota, Wisconsin, North Dakota, South Dakota, and Iowa) were reviewed for management recommendations and habitat preferences because, although some species are consistently associated with the same habitat variables (Noon et al., 1980), many species use habitats differently, have different habitat preferences, or respond to management practices differently in different geographic areas (e.g., Collins 1983a, 1983b, Kantrud and Kologiski 1983, Shy 1994). When sufficient information was not available from the north-central U.S., studies from Missouri, Nebraska, Illinois, the Michigan Upper Peninsula, and south central Canada were also used.
Care to see our RESULTS?
This web site resulted from preparation of a report submitted to the Mississippi headwaters/tallgrass prairie ecosystem team (U.S. Fish and Wildlife Service, Northcentral Region). Heidi Stallman and Rolf Koford prepared the paper version of the report. We appreciate the guidance we received from Steve Lewis (Nongame Migratory Bird Coordinator for the Region) in preparing this report. If the report proves useful to managers, it will be in large part because of his initiative, assistance, and attention to detail. Lynn Lewis, Project Officer for the FWS, was also very helplful. A hard copy of this report may be available through the Regional Office in Minneapolis, Minnesota.
Some Other WWW Resources for the Ecosystem
Minnesota Ornithologists' Union
North American Breeding Bird Survey
Northern Prairie Wildlife Research Center
Patuxent Wildlife Research Center
Updated January 1997.
Send comments to Rolf Koford,
Iowa Cooperative Fish and Wildlife Research Unit, Science Hall II, Iowa State University, Ames, IA 50011