Genetic and habitat factors underlying conservation strategies for Gunnison sage grouse

Abstract

The newly recognized Gunnison sage grouse (Centrocercus minimus) has declined markedly with extirpations in 12 of the 17 counties in southwestern Colorado which supported them in the early 1900's. Populations that remain are small and isolated, and exist in degraded and fragmented habitats. As a result, conservation of this species has become a significant concern. Particular issues of concern involve habitat quality and quantity, and genetic isolation from other populations. I developed a habitat-based model to: (1) identify the relative importance of landscape and micro-level variables, (2) examine the suitability of any sagebrush (Artemisia spp.) patch in southwestern Colorado, and (3) identify which patches have the highest probability of occupancy by sage grouse. The best model to make inferences from the data included patch area and distance to the nearest paved road. I quantified loss and fragmentation of sagebrush-dominated habitat using aerial photographic analysis. Between the mid-50's and the mid-90's, 20% of habitat was lost and sagebrush in 37% of the plots was fragmented. The Gunnison Basin had the lowest rate of habitat loss. I examined whether genetic data supported the new species designation of Gunnison sage grouse, and documented relative amounts of gene flow and genetic diversity between Gunnison sage grouse populations and northern sage grouse (C. urophasianus) populations from northern Colorado. My genetic data supported the species distinction, and I found that Gunnison sage grouse populations have less genetic diversity and gene flow than northern sage grouse. Incorporating data from the habitat and genetic studies, I developed a Geographic Information System (GIS) based model which consolidated current knowledge about Gunnison sage grouse so that managers could prioritize conservation strategies.