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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-71 Possible explanations for Sage-Grouse avoidance and extirpation of leks near transmission lines are: 1) Sage-Grouse directly avoid tall structures because they are adapted to inhabit treeless environments; 2) Sage-Grouse indirectly avoid transmission lines because they are avoiding the avian predators that are more abundant near transmission lines; or 3) a combination thereof. To date, no studies have examined mechanisms for Sage-Grouse avoidance of tall structures (UWIN 2010). As discussed above, use of transmission lines by avian predators is well documented (APLIC 2006; Knight et al. 1995; Steenhof et al. 1993) and densities of avian predators may increase near transmission lines (Howe et al. 2014). Dinkins et al. (2012) documented Sage-Grouse avoidance of avian predators in Wyoming. Nests and brood-rearing areas were located in areas with lower densities of ravens, magpies (Pica hudsonia), golden eagles (Aquila chrysaetos), and Buteo hawks compared with random locations. Reports on direct Sage-Grouse avoidance of transmission lines and effects on lek persistence are conflicting, with no clear consistent pattern evident among studies (Ellis 1984; Braun et al. 2002; Blomberg et al. 2010; Idaho Power Company 2010; Schroeder 2010; Wisdom et al. 2011; Stonehouse 2013). Research on this issue is reviewed and summarized in Appendix B-5 - Sage-Grouse Technical Report. While evidence for Sage-Grouse behavioral avoidance of transmission lines is minimal and evidence of decreased lek attendance and/or persistence is inconsistent, avoidance of transmission lines has been well documented for other prairie grouse species (Hagen 2003; Robel et al. 2004; Pitman et al. 2005; Pruett et al. 2009) and Sage-Grouse avoidance and/or lek decline has been well documented for other infrastructure, including communication towers, roads, and oil and gas development areas (Connelly et al. 2004; Holloran 2005; Johnson et al. 2011; Naugle et al. 2011; Dzialak et al. 2012; Harju et al. 2013). It remains unclear which, if any, of the effects documented for oil and gas development might also apply to transmission lines. Disturbance and avoidance effects on Sage-Grouse will depend on the proximity of Sage-Grouse to the proposed Project. Large portions of Alternatives A-H pass through the YTC Sage-Grouse 95 percent population range (Figure 3.3-4 and Table 4.3-4). Route segments passing through the population range include Route Segments 1b, 1c, 2a, 2b, 2c, and 2d. Of those six route segments, all but Route Segment 2d also pass through the core population range. The proposed NNR Alternative ROW is located entirely outside of the YTC Sage-Grouse population range, where 95 percent of Sage-Grouse use is estimated to occur. The eight-mile wide Sage-Grouse analysis area slightly overlaps the population range (by approximately eight percent), but does not overlap the core range, where 80 percent of Sage-Grouse use is estimated to occur (Figure 3.3-4 and Table 4.3-4). Recent use has been documented near Route Segments NNR-4, NNR-5, and NNR-6, but use appears to be infrequent. No Sage-Grouse were seen during ground transect surveys conducted in May and July of 2013; scat was observed in six locations adjacent to Route Segment NNR-6, one location on Route Segment NNR-5, and one location on Route Segment NNR-4 (Appendix B-1 - Sage-Grouse Survey Report). Based on 2015 data, there are four active leks, two inactive leks, and numerous historic leks known to occur within four miles of the proposed Project (Table 4.3-6). To ascertain the length of the proposed route segments that could have an impact on active leks and the nesting habitat that surrounds them, the length (miles) of the centerline within four miles of active leks was calculated (Table 4.3-6). Eight of the 18 route segments are within four miles of an active lek. Route Segment 2b has the longest length of line that is within four miles of an active lek (7.3 miles). RDFs expected to minimize the beneficial effect to avian predators and, thus, reduce Sage-Grouse avoidance of the proposed Project due to predator presence include: avoiding providing food subsidies to