Determining Greater Sage-grouse Abundance

Determining Greater Sage-grouse Abundance and Seasonal Landscape Use Patterns on the INL Site

 

     The Greater sage-grouse (Centrocercus urophasianus) has been the subject of research and monitoring efforts on the INL Site since the mid-1970s (Connelly 1982, Connelly 1988). Since 1995, sage-grouse have been monitored annually on the INL Site during the spring breeding season by counting the number of males on leks (i.e., areas where grouse congregate for courtship display and breeding) along designated routes. Three lek routes are currently monitored: two by S.M. Stoller Corporation (Stoller) and one by the Idaho Department of Fish and Game (IDF&G).
    Greater sage-grouse have received increasing attention from state and federal agencies as population levels have declined (Connelly et al. 2004; Idaho Sage-grouse Advisory Committee 2006). On March 5, 2010, the U.S. Fish and Wildlife Service (USFWS) reported its finding that listing greater sage-grouse as threatened or endangered under the Endangered Species Act of 1973 is warranted but precluded by higher priority actions. Thus, the USFWS currently recognizes the greater sage-grouse as a “candidate species” and will annually review its status to determine if changing conditions require that the bird be listed as threatened or endangered.
     The DOE-ID recognized that if greater sage-grouse or other sagebrush-obligate species were listed under the Endangered Species Act, potentially, further development and current activities on the INL Site could be delayed or halted to assess the potential effects on sage-grouse. Therefore, the Environmental Surveillance, Education and Research (ESER) Program, operated for DOE-ID by Stoller, began studying conservation actions that DOE-ID may take to minimize threats to sage-grouse.
We are documenting sage-grouse movements and seasonal habitat preferences across the Site using radio telemetry data gathered from greater sage-grouse fitted with radio transmission collars. These data will be used to parameterize spatially explicit statistical models that will characterize areas most used by sage-grouse on the Site. Greater sage-grouse on the Site were fitted with radio collars during the spring of 2008 and 2009. These birds have subsequently been tracked throughout the year on both the ground and in the air until the bird either died or the battery on the transmitter expired. Intensive monitoring of collared grouse allows us to locate nests and document nest success, and it facilitates the collection of habitat data that will help us better understand greater sage-grouse requirements for nesting, brood-rearing, and winter survival.



Figure 2. Movements of greater sage-grouse collared either in spring 2008 or 2009. Lines connecting points show estimated travel paths of birds.


Objectives

  • Track radio-collared sage-grouse from point of capture until the bird dies or the transmitter expires

  • Use telemetry data to develop a spatial model that will characterize nesting, brood-rearing, and winter habitats

  • Document nest locations and monitor nest success

  • Develop statistical models to estimate survivorship and population trajectory.


Accomplishments through 2009

  • In spring of 2008, 34 sage-grouse (22 females, 12 males) from 10 leks were fitted with radio collars. In 2009, 18 additional sage-grouse (9 males, 9 females) were collared.

  • Seasonal movements, nesting, brood-rearing, wintering, and mortality data have been collected for two seasons, and we are prepared to analyze these data in preparation for the drafting of a CCA.

  • All sage-grouse locations have been compiled in a Geographic Information System (GIS), and analysis of greater sage-grouse habitats has commenced.

  • Microhabitat data was collected in 2008 and 2009 at nest locations, and these data are currently being compiled into a proper database format.

Results
     Fifty-two sage-grouse, including 31 hens, have been collared during the past two years. In 2008, 20 nests were initiated, six of which were successful (30%), meaning that at least one egg hatched. Four of the 6 broods survived until the end of September, 2008. In 2009, 24 nests were initiated, 11 of which were successful (46% apparent next success). At least seven of the 11 broods survived until the end of the season in September, 2009, and the fates of two broods are unknown as the batteries in their radio collars expired before the end of the brood rearing season.
     Sage-grouse that breed on the INL Site are seasonally migratory, and collared birds displayed two general movement patterns. Many grouse captured on the northern portion of the Site migrated north into Birch Creek during the summer and fall, although two hens also traveled northeast near the Montana border (Figure 2). Some grouse captured on the southeast portion of the Site also migrated north into Birch Creek, but the majority moved south, east, and west. Although our sample size is small relative to the number of birds on the Site, these results suggest that birds on different regions of the Site may have different migration patterns which highlight the importance of following the movements of sage-grouse captured from various locations on the Site. We suggest that additional telemetry studies of greater sage-grouse be conducted in the central and western portions of the Site in order to determine the seasonal migratory patterns and critical habitat of greater sage-grouse in those areas.


Plans for Continuation
During 2010, we will organize all sage-grouse data collected on the Site since 2006 and draft a CCA between DOE-ID and USFWS. In May, 2010, DOE-ID will solicit feedback from the USFWS on an annotated outline of a draft CCA. In July, we will have prepared a first draft to be reviewed by DOE-ID.