The Greater sage-grouse (Centrocercus urophasianus) has been the subject of both research and monitoring on the INL Site since the mid-1970s. In 2006, S. M. Stoller, through the Environmental Surveillance, Education and Research Program, partnered with the Wildlife Conservation Society (WCS) to initiate a project that will culminate in the completion of a Conservation Management Plan (CMP) for a variety of animal species in the development zone on the INL Site. Because greater sage-grouse is considered a candidate species, one of the principle components of the CMP will be a Candidate Conservation Agreement between DOE-ID and the USFWS concerning conservation actions that DOE-ID will take to minimize threats to sage-grouse.
WCS is responsible for documenting sage-grouse occurrence and seasonal habitat preferences across the INL Site using radio telemetry data gathered from sage-grouse fitted with radio transmission collars. These data will be used to parameterize spatially explicit statistical models that will delineate the areas most used by sage-grouse on the INL Site. Sage-grouse on the INL Site were fitted with radio collars during the spring of 2008, 2009 and 2010. Sage-grouse 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 females allows technicians to locate nests and document nest success.
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 percent), 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 percent apparent nest 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.
Sage-grouse that lek on the INL Site tend to be seasonally migratory, and the data indicate that they migrated in at least two general patterns. Many grouse captured on the northern portion of the Site migrated north into Birch Creek during the summer and fall. Grouse captured on the southeastern portion of the Site remained in the vicinity of their leks or migrated south and east. Few grouse moved outside of these general patterns, and females almost never moved from one area (northern or southern) to another.
Throughout the summer of 2010, gathering of telemetry data will continue for nine sage-grouse whose collars continue to transmit a signal. During 2010, the investigators plan to organize all sage-grouse data collected on the INL Site since 2006 and draft a Candidate Conservation Agreement between DOE-ID and the United States Fish and Wildlife Service.
The objective is to survey historical leks that were previously identified by Jack Connelly (1982) and the Idaho Department of Fish and Game to determine if sage-grouse still use those sites.
Currently, 26 sage-grouse leks are known to be active on the INL Site. In addition, 61 leks are documented that were historically active but for which the current status is unknown. Surveys of historically documented leks were conducted on and adjacent to the INL Site in 2009. Only 57 of the historical leks were surveyed because the remainder either had been displaced by human activity, or a known active lek was close.
The 57 historical lek sites were visited one to three times (88 total visits). Surveys were performed, on average, 55 minutes after sunrise. Sage-grouse were not detected during surveys conducted in the most extreme weather events, such during rain storms or wind speeds over 6 km/h.
Sage-grouse were detected, either visually or audibly, on or near 14 historical and 2 previously undocumented leks. At least two males were detected on all but one (N5) of the 16 sites during the survey period. Each lek was classified according to Idaho Department of Fish and Game criteria. At lek N5, only one male was observed, so it could not be designated as active. The other 15 leks where sage-grouse were detected were designated as active. In addition, 6 leks were designated as inactive and 37 as unknown.
During the spring of 2010, all historical leks will be surveyed again, including the two that were newly identified in 2009. Ultimately, once all active sites are identified, the broader objective will be to quantify the number of males visiting leks from year to year (i.e., lek census) to understand population trends on the INL Site.