Dissertation/Thesis Abstract

Common raven density and greater sage-grouse nesting success in southern Wyoming: Potential conservation and management implications
by Dinkins, Jonathan B., Ph.D., Utah State University, 2013, 311; 3587560
Abstract (Summary)

My research was focused on greater sage-grouse ( Centrocercus urophasianus; hereafter "sage-grouse") nest-site selection, nest success, and hen survival in relation to avian predators. The trade-off between using habitat and avoiding predators is a common decision for prey species including sage-grouse. In Chapter 2, I compared avian predator densities at sage-grouse nest and brood locations to random locations. Sage-grouse were located where densities of small, medium, and large avian predators were 65-68% less than random locations.

The effects of anthropogenic and landscape features on habitat use of sage-grouse hens have not been evaluated relative to avian predator densities. In Chapter 3, I compared anthropogenic and landscape features and avian predator densities among sage-grouse locations (nest, early-brood, late-brood) and random locations. I found sage-grouse hens chose locations with lower avian predator densities compared to random locations, and selected locations farther away from anthropogenic and landscape features.

Depredation of sage-grouse nests can be an influential factor limiting their productivity. Predator removal has been simultaneously proposed and criticized as a potential mitigation measure for low reproductive rates of sage-grouse. In Chapter 4, I hypothesized that sage-grouse nest success would be greater in areas where Wildlife Services lowered common raven ( Corvus corax: hereafter "raven") density. I found that Wildlife Services decreased raven density by 61% during 2008–2011 but I did not detect a direct improvement to sage-grouse nest success. However, sage-grouse nest success was 22% when ravens were detected within 550 m of a sage-grouse nest and 41% when no raven was detected within 550 m. In Chapter 5, I assessed interactive effects of corvid densities relative to anthropogenic and landscape features on sage-grouse nest success. I found that sage-grouse nest success was positively correlated with rugged habitat.

Survival of breeding-age birds is the most important demographic parameter driving sage-grouse abundance. In Chapter 6, I evaluated the effect of raptor densities, proximity to anthropogenic and landscape features, and hen behavior on survival of sage-grouse hens. I found that sage-grouse hen survival was negatively correlated with golden eagle (Aquila chrysaetos) density, proximity to anthropogenic and landscape features, and hen parental investment (nesting and brood-rearing).

Indexing (document details)
Advisor: Conover, Michael R., Frey, Shandra Nicole
Commitee: Koons, David N., Messmer, Terry A., Wurtsbaugh, Wayne A.
School: Utah State University
Department: Wildland Resources
School Location: United States -- Utah
Source: DAI-B 74/11(E), Dissertation Abstracts International
Subjects: Wildlife Conservation, Wildlife Management, Conservation
Keywords: Common raven, Golden eagle, Greater sage-grouse, Hen survival, Nest success, Predator avoidance
Publication Number: 3587560
ISBN: 978-1-303-24848-1
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