BRYAN BEDROSIAN, CRAIGHEAD BERINGIA SOUTH
Figure 1. Male greater sage-grouse in flight during winter.
In general, species are located within a broadly defined range, but they use only specific habitats within their range, often seasonally. For example, in a field guide to birds you will often see a map showing seasonal ranges and migration areas with text describing which areas, such as wetlands, are most used within the range. Recent research maps historical and current greater sage-grouse (Centrocercus urophasianus; fig. 1, above; hereafter sage-grouse) range, which has been reduced about 50% since European settlement (Schroeder et al. 2004). The loss of sagebrush (Artemisia spp.) habitat is the main cause of the current decline in sage-grouse, and the sage-grouse was recently found “warranted but precluded” for listing as endangered under the Endangered Species Act (U.S. Fish and Wildlife Service 2010). Natural resource managers need to understand how sage-grouse populations use existing habitat to persist so that landscapes can be managed to prevent the listing of the species as endangered.
Studies that have used landscape-scale, spatial approaches to examine sage-grouse habitat selection (Homer et al. 1993; Aldridge and Boyce 2007; Moynahan et al. 2007; Carpenter et al. 2010) generally confirm the importance of well-developed sagebrush stands. Within sagebrush habitat, however, sage-grouse further refine their habitat selection. In general, studies show that relative to random sagebrush locations, sage-grouse select habitats with greater sagebrush height and cover (Crawford et al. 2004; Hagen et al. 2007). In winter, sage-grouse prefer sagebrush exposed approximately 25–35 centimeters (9.8–13.8 in) above snow, often on south- and west-facing slopes (Connelly et al. 2000; Crawford et al. 2004; Hagen et al. 2007). For nesting and early brood-rearing, sage-grouse prefer relatively tall (40–80 cm or 15.7–31.5 in) sagebrush of moderate to high canopy cover (15–25%) with a well-developed grass and forb understory (Connelly et al. 2000; Hagen et al. 2007). As forbs dry through the summer, female sage-grouse and their broods are found in increasingly moist and even riparian habitats (Wallestad 1971). During nesting and brood-rearing, sage-grouse avoid cropland, oil wells, other anthropogenic habitats, badland-type habitats, loamy upland sites, and habitat edges, but select habitats with a rich grass component (Aldridge and Boyce 2007; Moynahan et al. 2007).
In Wyoming, an area with relatively intact sagebrush habitat, male breeding-ground attendance dropped 50% from 1965 to 2003 (Connelly et al. 2004). Population declines in areas with intact habitats suggest that degradation of remaining habitats may be an important cause of sage-grouse population declines (Braun 1998; Connelly et al. 2000). The Jackson Hole, Wyoming, sage-grouse provide a unique opportunity to study a population that exists in a complex landscape with much less homogenous sagebrush than is typically found in areas occupied by sage-grouse, and which may be limited by winter habitat availability (USRBSGWG 2008). Our work provides an example of how habitat use can be studied to describe fine-scale, individual, seasonal selection within a larger landscape—whether for other sage-grouse populations or other species. This type of information may be used by natural resource managers to conserve critical habitats such as winter habitat.
The Jackson Hole, Wyoming, sage-grouse provide a unique opportunity to study a population that exists in a complex landscape with much less homogenous sagebrush than is typically found in areas occupied by sage-grouse, and which may be limited by winter habitat availability.
We investigated three main questions about sage-grouse habitat use across the Jackson Hole area: (1) which habitats do sage-grouse use? (2) how does habitat selection vary seasonally? and (3) how does habitat selection in a complex landscape differ from selection in sagebrush-dominated landscapes more typical of the species?
Chong, G. W., W. C. Wetzel, and M. J. Holloran. 2011. Research Report: Greater sage-grouse of Grand Teton National Park: Where do they roam? Park Science 27(3):42–49.
Available at http://www.nature.nps.gov/ParkScience/archive/PDF/Article_PDFs/ParkScience27(3)Winter2010-2011_42-49_Chong_et_al_2761.pdf.