Date of Award:
Master of Science (MS)
Terry A. Messmer
Greater sage-grouse (Centrocercus urophasianus; sage-grouse) are sagebrush obligates and are therefore considered to be key indicators of sagebrush ecosystem health. Sage-grouse populations have declined range-wide over the last century due to loss and fragmentation of sagebrush (Artemisia spp.) habitats. Sage-grouse populations found in large intact sagebrush landscapes are considered to be more resilient, however, some small isolated populations persist and thrive in fragmented landscapes. Because of Utah’s unique topography and geography, sage-grouse habitat is discontinuous and populations are naturally dispersed throughout the state in suitable intact blocks or in disconnected islands of sagebrush habitat. Thus, Utah populations provide the ideal place to understand how landscape attributes may influence at risk populations. Of these, the Morgan-Summit population is important because very little was known about the general ecology of this population and it experiences a high level of anthropogenic disturbances.
I examined seasonal movement patterns, habitat selection, vital rates (nest initiation rates, nest success, clutch size, breeding success, brood success, and survival probability of breeding age birds) and the influence of vegetation components on vital rates of a small geographically isolated sage-grouse population in Morgan and Summit Counties in northern Utah from 2015–2016. To collect the data, I deployed 25 very-high frequency radio collars and 10 platform terminal transmitters and completed micro-site vegetation surveys at nest, brood, and paired random sites and then made comparisons. Nest sites exhibited variation in vegetation structure that influenced nest success, while brood sites did not.
This population is one of the most productive in Utah exhibiting high nest initiation rates, hatching rates, and brood success rates despite limited habitat space and small seasonal movements. Transmitter type had no influence on vital rates, which is contrary to other studies, and limited influence on habitat selection. Sage-grouse avoided trees and developed areas, especially during the breeding season. Selection of other landscape variables was season-dependent. This information suggests that a sage-grouse population can occupy areas of limited habitat on an annual basis if seasonal habitat requirements are met. This study provides information that stake holders can utilize to conserve critical seasonal habitats within this study area where the population could be negatively affected by anthropogenic development pressure.
Flack, M. Brandon, "Ecology of Greater Sage-Grouse Inhabiting the Southern Portion of the Rich-Morgan-Summit Sage-Grouse Management Area" (2017). All Graduate Theses and Dissertations. 6899.
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