Influence of fine-scale habitat characteristics on sage-grouse nest site selection and nest survival varies by mesic and xeric site conditions La influencia de las caracteristicas del habitat a escala fina en la seleccion del sitio de anidacion y la supervivencia del nido de Centrocercus urophasianus varia segun las condiciones mesicas y xericas del sitio

Resource managers and scientists across western U.S. agencies seek methodologies for identifying environmental attributes important to both wildlife conservation and broad-scale land stewardship. The Greater Sage-Grouse (Centrocercus urophasianus; hereafter, sage-grouse) exemplifies a species in need of this broad-scale approach given widespread population declines that have resulted from loss and degradation of habitat from natural and anthropogenic disturbances. These include agricultural land conversion, conifer expansion, energy development, and wildfire coupled with ecological conversion by invasive plants such as cheatgrass (Bromus tectorum). Development of habitat assessments and conservation actions for sage-grouse benefit from studies that link demographic responses to habitat selection patterns. To address this, we examined nest survival of sage-grouse in relation to fine-scale habitat patterns (i.e., field-based habitat measurements) that influenced nest site selection, using data from nests of telemetered females at 17 sites over 6 years in Nevada and northeastern California, USA. Importantly, sites spanned mesic and xeric average precipitation conditions that contributed substantially to vegetation community structure across cold desert ecosystems of the North American Great Basin. Vegetative cover immediately surrounding sage-grouse nests was important for both nest site selection and nest survival, but responses varied between mesic and xeric sites. For example, while taller perennial grasses were selected at xeric sites, we found no evidence of selection for perennial grass at mesic sites, indicating a functional response to availability of habitat features between hydrographic regions. Furthermore, perennial grass height and forb height both had positive effects on nest survival at xeric sites, but we found varying effects at mesic sites. We emphasize that precipitation conditions driving ecosystem productivity vary regionally among sagebrush communities, shaping vegetation structure and suitable habitat conditions for nesting sage-grouse. Lay Summary center dot Effective conservation and management for sensitive species requires maintenance of habitat conditions that promote demographic success and persistence of populations. center dot We measured field-based fine-scale vegetation characteristics at nests of Greater Sage-Grouse across 17 sites within California and Nevada, USA, during 2012-2017, and we examined associations with nest selection and nest survival among female sage-grouse nesting in mesic and xeric sagebrush-steppe environments. center dot We demonstrate strong associations with fine-scale features and variation in these associations across precipitation conditions. Our results suggest differences in the regional availability of important vegetation components across xeric and mesic conditions that influence sage-grouse occurrence and reproductive success and highlight the importance of ecological context and long-term average precipitation when developing habitat management prescriptions. center dot Variation in the relative influences of herbaceous cover among habitat types within our study helps to elucidate discrepancies observed among studies of grass-related variables affecting selection or survival of sage-grouse nests.