Date of Award:
Master of Science (MS)
Terry A. Messmer
Greater sage-grouse (Centrocercus urophasianus) currently inhabit about 56% of pre-settlement distribution of potential habitat. In 2005, the Castle Country Adaptive Resources Management Local Working Group (CaCoARM) was formed to address concerns regarding local sage-grouse populations in Carbon and Emery counties. In 2006-2007, CaCoARM identified the Wildcat Knolls and Horn Mountain as areas of special concern for greater sage-grouse conservation. Both sites selected by the group were inhabited by what appeared to be small isolated sage-grouse populations. Factors limiting small isolated greater sage-grouse populations throughout its range are diverse and largely site-specific. During 2008-2009, I captured, radio-collared, and monitored 43 sage-grouse between the two populations to document their ecology and seasonal habitat use patterns. The sites are only 24 km apart, but the populations appear to be isolated from each other. Sage-grouse on Horn Mountain and Wildcat Knolls are one-stage migratory and non-migratory, respectively. Although nesting and brooding success varied between sites, my results were comparable to those published in studies throughout the species' range. Overall male survival was lower on the Wildcat Knolls than Horn Mountain (P = 0.003). Hens that selected brood sites exhibiting increased shrub cover and grass height were more successful than hens that selected sites with lower shrub cover and lower grass height. Potential nesting habitat on the Wildcat Knolls and Horn Mountain were estimated at 2,329 and 5,493 ha, respectively. Hens that selected nest sites farther from non-habitat edge were more successful than hens that selected nest sites that were closer to non-habitat edge on the Wildcat Knolls. Higher nest success observed on the Wildcat Knolls was attributed to less habitat fragmentation. Isolated populations of greater sage-grouse are more susceptible to lower amounts of genetic diversity that may lead to inbreeding depression and increased rates of disease and parasites. I collected mitochondrial DNA samples from both the Wildcat Knolls and Horn Mountain populations. Although the haplotype frequencies recorded in the Wildcat Knolls and Horn Mountain populations were low, one was shared with several Utah populations. The documented low genetic diversity (especially on Horn Mountain) confirmed the isolation suspected by the local working group. Microsatellite tests may provide insights to enhance understanding of genetic differences among sites, and assist managers in determining whether or not translocations are necessary to maintain population genetic diversity. Biologists should not only continue to take samples for genetic comparison, but also record morphometric and behavior data.
Perkins, Christopher J., "Ecology of Isolated Greater Sage-Grouse Populations Inhabiting the Wildcat Knolls and Horn Mountain, Southcentral Utah" (2010). All Graduate Theses and Dissertations. Paper 694.
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