The Ecology and Status of Sage Grouse in Montana

Abstract

We describe the ecology and status of the greater sage grouse (Centrocercus urophasianus) in Montana as part of an effort to develop a species conservation plan. Sage grouse are primarily associated with big sagebrush (Artemisia tridentata)-grassland although the original range has been greatly reduced or fragmented by a variety of human uses and activities. Efforts by the State's wildlife agency to delineate distribution of sage grouse in Montana during the 1960s and 1970s suggested that sage grouse occupied about 4.4 million ha in eastern and southwest Montana although more recent efforts to assess sage grouse habitat suggest occupied habitat could be as much as 10.9 million ha. Findings from studies during that period suggested that yearlong distribution and movements reflect regional or local conditions. That is, sage grouse tend to be nonmigratory in eastern Montana, where close interspersion of seasonal habitats rarely requires large movements, and migratory in the intermountain valley s of southwest Montana. Habitat requirements of sage grouse vary seasonally, in terms of structure and composition, to accommodate successful breeding and brood rearing and over-winter survival. Yearly precipitation patterns, in addition to habitat quality, can affect nesting success and chick survival. Data from statewide wing collections suggest that productivity of sage grouse declined from an average of 2.63 juveniles/hen during 1962-1979 to an average of 2.08 juveniles/hen during 1980-1992; drought conditions were more frequent during the latter period. An estimate of mortality of sage grouse during the first y ear of life approaches 85 percent of which about two-thirds occurs prior to the opening of the upland bird hunting season in September. Sage grouse populations in southwestern Montana have declined from the 1960s through the 1980s following a period of large-scale sagebrush manipulation and conversion of native range to cropland. Numbers of birds remain relatively abundant throughout areas of central and eastern Montana that continue to support large, unfragmented stands of big sagebrush. Several stateinitiated programs offer incentives to private landowners to maintain or enhance habitat quality for sage grouse and other wildlife species.