Thesis
USING EXPERIMENTAL MANAGEMENT TO ASSESS LARVAL SURVIVAL AND HABITAT QUALITY CHARACTERISTICS OF OREGON SILVERSPOT BUTTERFLY
Master of Science (MS), Washington State University
2026
Abstract
Habitat loss is a leading driver for butterfly declines. Restoring habitat quality through disturbance-based management is widely used as a conservation approach for at-risk butterflies, but success of this strategy can be limited without carefully designed monitoring of butterfly and habitat responses. Habitat for vulnerable butterflies includes plant resources to support all lifecycle stages and structural conditions for sustaining plant growth and butterfly use. Common conservation approaches focus on increasing host plant resources yet often overlook the importance of habitat structure. Using an experimental framework, we tested disturbance-based management effects on Oregon silverspot (Speyeria = Argynnis zerene hippolyta) 1) butterfly larval survival and 2) associated larval habitat quality characteristics: host plant cover and vegetation thickness. We applied flail mowing and prescribed fire management treatments at two field sites with responses of post-diapause larval survival, host plant cover, and vegetation thickness measured over two years after management application. Our results suggested that decreasing vegetation thickness enhances Oregon silverspot larval survival. Larval survival was higher in the first spring when host plant cover was lower and vegetation thickness was lower compared to the second spring with lower larval survival despite higher host plant cover. From additional testing of habitat quality characteristic effects on larval survival in the second study year, larval survival was higher in clipped vegetation plots compared to non-clipped plots. Violet cover above minimum amounts needed for foraging did not affect larval survival. Together, our results indicate that given sufficient host plant resources, disturbance-based conservation management that reduced vegetation structure supported survival of Oregon silverspot to adult stage. We recommend use of disturbance-based management to open vegetation structure for enhancing habitat quality to support at-risk butterfly larval survival.
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Details
- Title
- USING EXPERIMENTAL MANAGEMENT TO ASSESS LARVAL SURVIVAL AND HABITAT QUALITY CHARACTERISTICS OF OREGON SILVERSPOT BUTTERFLY
- Creators
- Emma Clare Dombrow
- Contributors
- Cheryl Schultz (Advisor)Rich Van Buskirk (Committee Member)Erica Henry (Committee Member)Jonah Piovia- Scott (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Biological Sciences
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Number of pages
- 71
- Identifiers
- 99901417106301842
- Language
- English
- Resource Type
- Thesis