Environmental drivers of Greater Sage-grouse population trends over 25 years in Idaho, USA

Ecosphere
By: , and 

Links

Abstract

Greater Sage-grouse (Centrocercus urophasianus) populations have been in decline for decades across much of the US Intermountain West. However, findings from 25 years of lek counts in Idaho indicate that some populations are stable or even increasing. After accounting for potential biases in past lek count data, we sought to explain the variability in population trends among all 70 lek clusters (i.e., populations) we identified in the state. For each population, we identified lek count troughs, or low-point years, that occurred between the mid-1990s and 2021 and used a regression slope of those abundance low points to quantify each population's trend over the 25-year time span. We related the 70 populations' slopes to climate, fire, topographic, vegetation, and landcover variables. Our analyses revealed that populations with negative trends tend to occur toward the ends of climate gradients (i.e., extremes of occupied habitats) and in locations with more wildfire, agriculture, and riparian landcover. Populations with positive trends generally occur in landscapes toward the middle of the climate gradient, with high amounts of low sagebrush (Artemisia arbuscula) landcover and intermediate amounts of riparian and agricultural landcover. Post hoc analysis indicated that the latter two drivers were strongly associated with high raven occupancy rates, which may contribute to the negative sage-grouse population trends we observed in areas with high riparian or agricultural landcover. When modeled separately for different regions however, various region-specific drivers were identified, including tree cover, annual herbaceous cover, and human development. This information can help guide sage-grouse habitat management decisions and set expectations for population recovery, given the diversity of habitats occupied by the species and the cyclic nature of sage-grouse populations.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Environmental drivers of Greater Sage-grouse population trends over 25 years in Idaho, USA
Series title Ecosphere
DOI 10.1002/ecs2.70331
Volume 16
Issue 9
Publication Date September 16, 2025
Year Published 2025
Language English
Publisher Ecological Society of America
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description e70331, 20 p.
Country United States
State Idaho
Additional publication details