Date of Award:
Doctor of Philosophy (PhD)
Terry A. Messmer
Due to loss of habitat, Gunnison sage-grouse (Centrocercus minimus) currently occupy 8.5% of their presumed historical range. One population survives in Utah, occurring in San Juan County. The Gunnison Sage-grouse Rangewide Conservation Plan and the San Juan County Gunnison Sage-grouse Conservation Plan recommended management strategies to address identified conservation threats to the Utah population. I addressed three conservation strategies identified in the plans: 1) creation and enhancement of brood-rearing areas; 2) assessment of habitat conditions within the Gunnison Sage-grouse Conservation Area; and 3) prevention or reduction of perching events by avian predators on distribution line power poles.
From 2007-2009, I addressed the conservation strategy of creating mesic brood-rearing areas in Conservation Reserve Program fields and native sagebrush areas by evaluating the role of irrigation and dormant season cattle grazing on habitat. Vegetation and arthropod diversity in irrigated versus non-irrigated plots did not differ (p>0.01). Conservation Reserve Program plots exhibited greater arthropod abundance and cover of perennial grass than the native sagebrush plots, but lower diversity of perennial grasses and abundance and diversity of forbs (p<0.01).
The second conservation strategy I addressed was the completion of an assessment of habitat conditions within the Gunnison Sage-grouse Conservation Area. I measured vegetation conditions within habitat occupied and unoccupied by Gunnison sage-grouse. Cover and height of grasses exceeded guidelines for occupied and unoccupied habitats. Forb cover was below recommended guidelines in occupied habitat. Sagebrush cover was below guidelines for winter habitat. Habitat restoration efforts should focus on retaining existing sagebrush cover and establishment of sagebrush, forb, and grass cover within Conservation Reserve Program fields.
The third conservation strategy I evaluated was the retrofitting of distribution line power poles with perch deterrents to discourage avian predators from perching. I evaluated the efficacy of five perch deterrents. The perch deterrents did not mitigate potential avian predators from perching. A deterrent designed for insulators, in combination with physical deterrents we tested, has potential to prevent perching.
These studies provided a sound first step that can be built upon by the Monticello/Dove Creek Local Working Group to improve habitat conditions, reduce the threat of avian predation, and plan future conservation activities within the Conservation Area.
Prather, Phoebe R., "Factors Affecting Gunnison Sage-Grouse (Centrocercus minimus) Conservation in San Juan County, Utah" (2010). All Graduate Theses and Dissertations. 827.
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