Wildlife Research and Management - Wildlife Research
Date Published: October 03, 1996
Number of Pages: 7
Author(s): Michael A. Schroeder
Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) were historically found throughout many of the meadow and shrub steppe habitats of eastern Washington (Yocom 1952, Aldrich 1963). However, statewide populations of sharp-tailed grouse have declined precipitously as the result of three major factors: 1) removal of shrubs as part of various agricultural practices has reduced the quantity and quality of winter habitat; 2) degradation of meadow and shrub steppe habitat as a result of livestock management has reduced the quality of breeding habitat; and 3) isolated populations are at increased risk of extinction. Surveys indicate that sharp-tailed grouse are primarily restricted to Okanogan, Douglas, and Lincoln counties (Zeigler 1979, Weddell et al. 1992, Tirhi 1995). Remaining populations appear to be relatively small and isolated, corresponding to partially intact and/or restored areas that provide adequate breeding and wintering habitat (Marshall and Jensen 1937, Yocom 1952, Marks and Marks 1988, Zeigler 1979, Giesen 1987, Meints et al. 1992, Giesen and Connelly 1993).
Populations in north-central Washington are clearly becoming more isolated every year. The isolation of populations may have important ramifications on their genetic quality and/or recruitment. However, it is not yet clear if the Washington populations are declining because of their isolation or because of a combination of other factors. For example, removal and degradation of riparian, shrub steppe, and meadow steppe habitat has clearly reduced the availability of both breeding (nesting and brooding) and winter habitat for sharp-tailed grouse in Washington.
Breeding habitat for sharp-tailed grouse should include relatively thick grass and forb cover. Winter habitat should include a diversity of deciduous shrub and tree species in close proximity to relatively thick grass and forb cover. Although adequate breeding habitat is often infrequent, there are several factors that indicate that declining quantity and quality of ' winter habitat may be the most significant factor in the large-scale declines of sharp-tailed grouse. First, although annual survival of radio-marked birds in Washington appears to be relatively high (53%), there is a trend toward higher mortality during winter (Schroeder 1994); this trend is very unusual among grouse.
Second, blue grouse (Dendragapus obscurus) still nest in many of the areas formerly occupied by sharp-tailed grouse, despite the fact that both nest in similar habitats. Because blue grouse move away from shrub and meadow steppe habitats to winter areas in conifer habitats, their populations apparently have not been at risk (Zwickel 1972).
Third, evidence from research in Washington has indicated that breeding success of radio-marked birds is high (Schroeder 1994). Consequently, it is difficult to support a conclusion that good quality breeding habitat is limiting on a small scale. On a large scale, sage grouse (Centrocercus urophasianus) continue to nest successfully in areas formerly occupied by sharptailed grouse. The primary change in the areas occupied by sage grouse is the replacement of shrub steppe habitat and riparian areas with wheat.
Fourth, virtually all remaining populations in north-central Washington are increasingly restricted to 'high' elevation habitats~ These high elevation sites have relatively high quality habitats (both shrubs and grasses); they are characterized by cooler temperatures, wetter climates, and reduced grazing pressure.
Fifth, the low elevation sites were historically the best winter habitats; these sites had the best riparian areas, shrub cover, and weather conditions. Low elevation sites have been altered the most; they have been converted to orchards, roads, houses, and lakes. The remaining shrub steppe habitat at low elevations is in extremely poor condition and is not likely to provide useful cover for wintering populations of sharp-tailed grouse.
Sixth, the concentration of sharp-tailed grouse at low elevations during winter has resulted in heavy harvest pressure. This was primarily due to the easy assess by hunters, but also due to the removal of birds from orchards because of concerns about crop-damage.
As a result of these six factors, populations of sharp-tailed grouse have been restricted to isolated high-elevation islands of habitat in north-central Washington. The long-term prospects improvement of habitat must be evaluated in terms of land-use realities. For example, because it is unlikely that sharp-tailed grouse will ever be compatible with orchards, the corridors along the Okanogan, Methow, and Columbian rivers will never be occupied by stable populations of sharp-tailed grouse again. Consequently, habitat improvement efforts should be directed toward the following situations: 1) improve shrub steppe habitats in riparian corridors within 0.5 km of acceptable winter habitat (must provide cover in deep snow); 2) restore riparian or deciduous shrub habitats in upland areas dominated by shrub or meadow steppe habitat (shrubs should vary between 0.5 and 2.5 m in height); and 3) improve the condition of shrub and meadow steppe habitat throughout the potential range of sharp-tailed grouse.
Populations of sharp-tailed grouse in north-central Washington offer a unique opportunity to implement and evaluate various management strategies. Many current (and historic) populations are found on, or adjacent to, state or federal public property that is managed by the Washington Department of Fish and Wildlife, the Washington Department of Natural Resources, the U. S. Bureau of Land Management, and the U. S. Forest Service. For example, the Washington Department of Fish and Wildlife owns and manages the Methow, Scotch Creek, Tunk Valley and Chesaw Wildlife Areas, often with the goal of improving conditions for sharptailed grouse. The purpose of this report is to address the feasibility of expanding goals of sharptailed grouse management to adjacent areas of public property, primarily the U. S. Forest Service. Consequently, this report has three specific objectives: 1) examine the location of historic and current sharp-tailed grouse habitat in relation to the Okanogan National Forest in Okanogan County, Washington; 2) determine which area (or areas) of the Okanogan National Forest offer the greatest potential for sharp-tailed grouse; and 3) consider the types and practicalities of management options which may influence sharp-tailed grouse on, and adjacent to, the Okanogan National Forest.