Greater sage-grouse winter habitat use on the eastern edge of their range

Greater sage-grouse (Centrocercus urophasianus) at the western edge of the Dakotas occur in the transition zone between sagebrush and grassland communities. These mixed sagebrush (Artemisia sp.) and grasslands differ from those habitats that comprise the central portions of the sage-grouse range; yet, no information is available on winter habitat selection within this region of their distribution. We evaluated factors influencing greater sage-grouse winter habitat use in North Dakota during 20052006 and 20062007 and in South Dakota during 20062007 and 20072008. We captured and radio-marked 97 breeding-age females and 54 breeding-age males from 2005 to 2007 and quantified habitat selection for 98 of these birds that were alive during winter. We collected habitat measurements at 340 (177ND, 163SD) sage-grouse use sites and 680 random (340 each at 250m and 500m from locations) dependent sites. Use sites differed from random sites with greater percent sagebrush cover (14.75% use vs. 7.29% random; P<0.001), percent total vegetation cover (36.76% use vs. 32.96% random; P0.001), and sagebrush density (2.12plants/m2 use vs. 0.94plants/m2 random; P0.001), but lesser percent grass cover (11.76% use vs. 16.01% random; P0.001) and litter cover (4.34% use vs. 5.55% random; P=0.001) and lower sagebrush height (20.02cm use vs. 21.35cm random; P=0.13) and grass height (21.47cm use vs. 23.21cm random; P=0.15). We used conditional logistic regression to estimate winter habitat selection by sage-grouse on continuous scales. The model sagebrush cover+sagebrush height+sagebrush coverxsagebrush height ($w_{i} $=0.60) was the most supported of the 13 models we considered, indicating that percent sagebrush cover strongly influenced selection. Logistic odds ratios indicated that the probability of selection by sage-grouse increased by 1.867 for every 1% increase in sagebrush cover (95% CI=1.6272.141) and by 1.041 for every 1cm increase in sagebrush height (95% CI=1.0021.082). The interaction between percent sagebrush canopy cover and sagebrush height (=0.01, SE0.01; odds ratio=0.987 [95% CI=0.9830.992]) also was significant. Management could focus on avoiding additional loss of sagebrush habitat, identifying areas of critical winter habitat, and implementing management actions based on causal mechanisms (e.g., soil moisture, precipitation) that affect sagebrush community structure in this region. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.