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MANAGEMENT PLAN AND CONSERVATION
STRATEGIES FOR SAGE GROUSE IN MONTANA FINAL
Image by Bob Martinka
Prepared by: Montana Sage Grouse Work Group Rev. 2-1-2005
EXECUTIVE SUMMARY Growing concern about the status of sagebrush (Artemisia spp.) on western rangelands and declines in sage grouse (Centrocercus urophasianus) numbers have led to petitioning the Fish and Wildlife Service of the U.S. Department of Interior to protect populations in some western states under provisions of the federal Endangered Species Act. Loss of sagebrush-grasslands in some western states has approached or exceeded 50 percent. Such habitat loss in Montana, in terms of quality or quantity, may not have been as high as in other states although significant enough at least in part of the state to influence sage grouse numbers and population trends. A Memorandum of Understanding (MOU) for the conservation and management of sage grouse was signed by member states of the Western Association of Fish and Wildlife Agencies (WAFWA) and federal natural resource management agencies. Members of these organizations have agreed to work cooperatively to develop conservation plans for sage grouse in each of 11 western states. Each state member of WAFWA agreed to convene a working group within 60 days of the effective date of the MOU12 July 2000. Purpose of the Plan Montanas conservation strategy provides for coordinated management across jurisdictional boundaries and development of community support that will promote successful implementation. Participants in the Montana sage grouse work group (SGWG) who have developed the plan include representatives of federal and state agencies, tribal representatives, private organizations, and several individuals from the general public, all of whom have an interest in the issue of sage grouse conservation. The plan establishes a process to achieve sage grouse management objectives and provide a framework to guide local management efforts and coordinated management across jurisdictional boundaries. Regional or local groups will adapt and implement strategies from the statewide plan to improve or maintain the sagebrush steppe in their respective geographical areas. Throughout development of the plan, numerous views were expressed that emphasized the need to keep sage grouse management in balance with social, cultural, and community values. The overall goal of the plan is to Provide for the long-term conservation and enhancement of the sagebrush steppe/mixed-grass prairie complex within Montana in a manner that supports sage grouse and a healthy diversity and abundance of wildlife species and human uses. Objectives include maintaining the distribution and integrity of sagebrush steppe communities and maintaining the distribution of sage grouse populations within the mountain foothills mixed sagebrush and Wyoming big sagebrush-silver sagebrush ecotypes based on a consistently applied monitoring protocol. Distribution and Habitat Needs of Sage Grouse Sage grouse are native to the sagebrush steppe of western North America, and their distribution closely follows that of sagebrush, primarily big sagebrush (A. tridentata). Distribution of sage grouse in Montana includes the eastern one-half and southwest corner of the stateroughly 27 million acres (11 million ha) of sagebrush-grassland in 39 counties.
In eastern Montana, where close interspersion of wintering, nesting, and brood-rearing habitat rarely require large seasonal movements, sage grouse are essentially nonmigratory. Some sage grouse in southwestern Montana are migratory, moving between separate summer and winter areas. Migratory movements of sage grouse also have been documented between eastern Idaho and southwest Montana. Seasonal movement often is elevational and related to availability of herbaceous vegetation during late summer and early fall. The following seasonal habitats are important for survival of sage grouse:
Breeding Habitat.Strutting grounds or leks, where breeding actually occurs, are key activity areas and most often consist of clearings surrounded by sagebrush cover. Findings from research in central Montana reported a sagebrush canopy cover at feeding and loafing sites in the vicinity of leks of 20-50 percent with an average of 32 percent.
Nesting Habitat. Sage grouse invariably prefer sagebrush for nesting cover, and quality of nesting cover directly influences nest success. Successful nesting requires concealment provided by a combination of shrub and residual grass cover. Sage grouse most frequently select nesting cover with a sagebrush canopy of 15-31 percent. Research findings in central Montana suggest that about two-thirds of nests occur within 2 miles of a lek.
Brood-Rearing Habitat.Areas providing an abundance and diversity of succulent forbs, an important summer food source for young sage grouse, provide key brood-rearing habitat. Research in central Montana indicated that sage grouse broods prefer relatively open stands of sagebrush during summer, generally with a canopy ranging from 1-25 percent. As palatability of forbs declines, sage grouse move to moist areas that still support succulent vegetation, including alfalfa fields, roadside ditches, and other moist sites. During summers of high precipitation, sage grouse in Montana may remain widely distributed throughout the entire summer due to the wide distribution of succulent forbs. Sage grouse in southwest Montana and eastern Idaho often move to intermountain valleys during late summer where forbs remain succulent through summer and early fall. Reported sagebrush canopy on these sites varied from 8.5 to 14 percent.
Winter Habitat. Sage grouse generally select relatively tall and large expanses of dense sagebrush during winter. Wintering areas in central Montana included sagebrush stands on relatively flat sites with a 20-percent canopy and an average height of 10 inches. The importance of shrub height increases with snow depth. Thus, snow depth can limit the availability of wintering sites to sage grouse.
Population Dynamics Counts of males on leks during spring have been used to provide an index of relative size and trend of breeding populations of sage grouse in Montana since the 1950s. Statewide, sage grouse numbers increased from the mid-1960s through 1973 and fluctuated about that level until 1984. Sage grouse declined rather sharply statewide from 1991 through 1996 and increased through 2000. Long-term harvest trends, based on post-hunt surveys of hunters, when interpreted along with lek counts, also provide insight to long-term changes in sage grouse numbers at a statewide scale.
Productivity has been estimated from examination of wings of grouse taken by hunters. In addition to the quantity and quality of breeding and nesting habitat, the amount and timing of spring and summer rainfall may affect annual production and population dynamics of sage grouse. Nest success and early brood survival rates are some of the most significant vital rates influencing population dynamics of prairie grouse and other upland nesting species. Juvenile mortality during the first few weeks after hatching is typically high and can increase when drought reduces availability of important food sources, such as insects and forbs, or herbaceous understory, used as hiding and escape cover. Research documented an average mortality rate of 56 percent in central Montana from the egg-laying period in April to early September. Survival rates for adult sage grouse are generally considered to be high, and thus population declines are usually not related to high levels of predation on adult birds. Adult hens are most vulnerable to predation during the nesting period, whereas adult males are most vulnerable during the spring breeding season. Management Sage grouse are managed as an upland game bird under state legislative authority including the statutory mandate of the Fish, Wildlife and Parks Commission to regulate harvest. FWP, in conjunction with federal land management agencies and conservation groups, monitors prairie grouse populations during spring through census of displaying males on leks. The post-harvest telephone survey provides an estimate of harvest for all upland bird species, trend in hunter numbers, and number of birds by species taken by hunters. FWP uses wings from harvested sage grouse to estimate composition of the harvest by sex and age, although some regions discontinued collections during the mid-1980s. State-funded cooperative habitat projects have the potential to benefit sage grouse on private and other non-tribal land. In 1987, the Montana Legislature created a process and funding source for FWP to acquire conservation easements on or to purchase important wildlife habitat in Montana. The program generates funding from an earmarked portion of license revenue and provides an innovative tool to protect habitat at the state level. The Upland Game Bird Habitat Enhancement program, which authorizes FWP to use earmarked funds for habitat improvement for upland game birds, also was enacted in 1987 and amended in 1989. It too allows for the use of conservation easements and habitat enhancement to improve conditions for sage grouse. Issues Requiring Conservation Actions During the conservation planning effort, the Montana sage grouse work group identified risks to sage grouse and their habitat. The group then identified 12 major issues in sage grouse conservation and, considering the social and economic implications posed by the risks themselves, developed possible