Date of Award:

8-2023

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Committee Chair(s)

S. Nicki Frey

Committee

S. Nicki Frey

Committee

Michael Conover

Committee

Eric Gese

Abstract

Certain species of wildlife are more generalist and adaptive than others. These species often flourish when supported by human activities that provide additional food and habitat for them. The common raven (Corvus corax; hereafter raven) is one such species; their populations have risen and spread throughout the Intermountain West. As generalist scavengers and predators, ravens have been found to pose a severe threat to several threatened or sensitive species, including the greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse). The purpose of my research was to determine the specific anthropogenic and habitat factors that may increase the threat that ravens pose as sage-grouse nest predators in southern Utah. To do this, I conducted surveys for ravens in the winter and spring months (February-June) in 2021 and 2022. I also completed artificial nest experiments during the same years by placing chicken eggs underneath sagebrush with the intent of determining what habitat factors led to more instances of nest depredation by ravens. Through my surveys, I found that raven presence was significantly affected by the calendar date of the survey, how far the survey was from agricultural practices, and whether or not livestock was present during the survey. During the artificial nest experiment, I found that ravens were more likely to find and depredate nests that were within habitat that had been treated for pinyon-juniper removal compared to intact sagebrush. I also found that the nests were more likely to be depredated if they were placed underneath a shrub that was close to a nest that a raven had found and depredated. My research will help to inform sage-grouse management decisions that pertain to sagebrush vegetation treatments and raven mitigation strategies.

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