Date of Award:
Master of Science (MS)
Terry A Messmer
Greater sage-grouse (Centrocercus urophasianus; sage-grouse) currently occupy an estimated 56% of the potential range-wide pre-European settlement habitat. Population declines have been largely attributed to direct habitat loss and fragmentation related to anthropogenic activities that promote wildfires and the subsequent spread of invasive plants. Vegetation manipulations, including the seeding of plant species, such as forage kochia (Bassia prostrata), have been identified as potential strategies to mitigate the risk of wildfire and enhance sage-grouse habitat in areas at risk to wildfires. I evaluated the composition changes that occurred in a lower elevation sagebrush (Artemisia spp.) plant community within the Grouse Creek Watershed in western Box Elder County, Utah, USA, in response to prescribed vegetation manipulations (green-stripping through chain harrowing, juniper mastication, seeding forage kochia, applying Plateau® herbicide) and studied the effect of these changes on sage-grouse habitat-use patterns and vital rates. I monitored 53 radio-collared sage-grouse throughout the Grouse Creek watershed from 2010-2012. Seasonal movements suggested local individual bird adaptations to annual variations in weather and habitat fragmentation. Sage-grouse selected for untreated areas; however, treated areas were used to expand the size of the lek. Untreated areas exhibited a higher percent composition of shrubs compared to areas that were chain harrowed to prepare a seedbed. Sage-grouse nest success and adult male survival rates during this study were relatively low compared to range-wide population estimates. Nest predation was higher for nests located closer to roads. The forage kochia seeded in the firebreaks emerged the season after seeding (2011). Using microhistological techniques, I detected small quantities of forage kochia in sage-grouse fecal pellets. Nutrient analysis confirmed that forage kochia samples collected from the sites exhibited a high protein content and low secondary metabolite content, similar to black sagebrush (Artemisia nova). Although greenstripping with forage kochia in lower elevation sagebrush communities may prove to be a beneficial technique for protecting rangelands from wildfire and provide a dietary source for wildlife, site preparation should be conducted to minimize the impact on existing sagebrush canopy cover habitats. Long-term monitoring should be implemented to determine extended effects of greenstripping treatments on sagebrush habitat and sage-grouse vital rates. Although individual sage-grouse demonstrated local adaptations to fragmentation and seasonal variations in weather, increased fragmentation and climate change in this part of the Great Basin may increase meta-population extirpation risks inhabiting lower elevation sagebrush areas in the Grouse Creek Watershed.
Graham, Stephanie E., "Greater sage-grouse habitat selection and use patterns in response to vegetation management practices in northwestern Utah" (2013). All Graduate Theses and Dissertations. 1971.
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