Greater sage-grouse as an umbrella species for shrubland passerine birds: a multiscale assessment

Abstract

Working groups and government agen-cies are planning and conducting land actions in sagebrush (Artemisia spp.) habitats to benefit Greater Sage-Grouse (Centrocercus urophasianus) populations. Managers have adopted an umbrella concept, creating habitat characteristics specific to sage-grouse requirements, in the belief that other wildlife species dependent on sagebrush will benefit. We tested the efficacy of this approach by first identifying the primary environmental gradients underlying sagebrush steppe bird com-munities (including Greater Sage-Grouse). We integrated field sampling for birds and vegetation with geographic information system (GIS) data to characterize 305 sites sampled throughout the current range of Greater Sage-Grouse in the Intermountain West, United States. The primary environmental axis defining the bird community represented a gradient from local-scale Wyoming/basin big sagebrush (A. t. ssp. wyomingensis/A. t. ssp. tridentata), and bare ground cover to local and regional grassland cover; the second axis repre-sented a transition from low-elevation Wyoming/basin big sagebrush and bare ground to mountain big sagebrush (A. t. ssp. vaseyana) and habitat edge. We identified the relative overlap of sage-grouse with 13 species of passerine birds along the multiscale gradients and estimated the width of the umbrella when applying management guidelines specific to sage-grouse. Passerine birds associated with sagebrush steppe habitats had high levels of overlap with Greater Sage-Grouse along the multiscale environmental gradients. However, the overlap of the umbrella was prima-rily a function of the broad range of sagebrush habitats used by sage-grouse. Management that focuses on creating a narrow set of plot-scale con-ditions will likely be less effective than restoration efforts that recognize landscape scale heterogene-ity and multiscale organization of habitats. These multiscale efforts may improve some sage-grouse habitats and strengthen the management umb-rella for shrub steppe passerine birds.