Date of Award:

8-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Committee Chair(s)

S. Nicole Frey

Committee

S. Nicole Frey

Committee

Erica Stuber

Committee

Dustin H. Ranglack

Abstract

Common Ravens have become increasingly common across the Great Basin of the western USA, largely because human activities, such as roads, agriculture, livestock operations, and human-made structures, provide them with abundant food, water, and nesting sites. As raven numbers have grown, so has their impact on vulnerable species like the greater sage-grouse. Like many other ground-nesting species, greater sage-grouse eggs and chicks are especially susceptible to predation. To help reduce raven numbers in sensitive areas, wildlife managers often place hard-boiled chicken eggs treated with a toxin (DRC-1339) on the landscape, expecting that ravens will die after eating these eggs and that their population will be reduced. However, very little research has examined what happens to these eggs once they are placed in the field or which other species may consume them. I conducted a two-year study in central Nevada to evaluate how ravens find, handle, and use egg baits, and how the surrounding habitat influences these outcomes. I monitored more than 500 bait sites with trail cameras to see which animals interacted with the eggs. I found that ravens removed fewer eggs than expected and that many eggs were taken by non-target species such as black-billed magpies, coyotes, and rodents. Eggs were more likely to be taken by ravens when placed on fence posts, in open areas with little shrub cover, or near hay bales. I also used small transmitters placed inside chicken eggs to track what ravens did with the eggs they carried away from bait sites. Most of these eggs were not eaten immediately but were hidden under soil or plant material, sometimes hundreds of meters away from where we set them. Ravens rarely returned to these eggs during the short period when the toxin remains lethal, meaning many treated eggs may not actually result in raven deaths. These findings show that raven behavior and local habitat conditions strongly influence the success of egg-bait control programs. By understanding where ravens are most likely to take eggs, how they handle them, and how often non-target species remove them, wildlife managers can improve the design and placement of bait sites to make these programs more effective and safer for other wildlife.

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