Extensive Use of Agricultural and Conservation Fields by Male Greater Sage-Grouse in Washington State

Greater sage-grouse ( Centrocercus urophasianus ) have declined across much of their range, including extirpation of many populations at the range edge. Along the northwestern range edge in Washington state, sage-grouse populations must persist within a landscape that contains heavily fragmented sagebrush habitat surrounded by a matrix of agricultural fields. Recently, two of the Washington populations were extirpated and two others declined sharply, highlighting the need to better understand how resident populations have adapted to a fragmented agriculture-dominated landscape to aid management decisions. We analyzed GPS collar data from 24 male sage-grouse in Washington to assess habitat selection. Sage-grouse used shrub-steppe more than any other landcover class, but less than it was available on the landscape, suggesting not all shrub-steppe is of equal quality for sage-grouse. Notably, sage-grouse utilized both agricultural and conservation fields (i.e., Conservation Reserve Program (CRP) and State Acres for Wildlife Enhancement [SAFE]) more than they were available across the landscape, but that use varied seasonally with the most use occurring in the lekking and summer seasons. Use of fallow fields peaked between June and August, while winter wheat fields were primarily used from August to October, suggesting these fields were supplying important supplemental resources during those times (e.g., wheat kernels after harvest). Sage-grouse tended to stay closer to the edge of agricultural fields and nearer to shrub-steppe than random locations, indicating that the complex mosaic of landcover types on the landscape may aid persistence. These results highlight the need for nuanced land management for sage-grouse in Washington. Importantly, this confirms the need to maintain CRP and SAFE fields in Washington to slow population declines.