Theses and Dissertations
Date of Award
5-1-2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Andrea Contina
Second Advisor
Karl Berg
Third Advisor
Alejandro Fierro Cabo
Abstract
Migration enables species to exploit seasonal resources despite high energetic costs and mortality risks, making it a key focus for conservation under environmental change. I investigated migratory connectivity in Orange-crowned Warblers using stable hydrogen isotopes (δ²H) from feathers collected at nine non-breeding sites across Mexico. Results indicated generally weak connectivity (MC = 0.18), with most sites hosting individuals from six breeding clusters across Canada and the United States. However, one northwestern breeding group showed strong connectivity, suggesting crosswise migration to eastern Mexico. By integrating these findings with long-term Breeding Bird Survey data, I detected contrasting population trends, with Pacific Coast populations experiencing the steepest declines. This mixing of populations with different demographic trajectories at shared non-breeding sites may obscure declines in vulnerable groups. These results highlight the importance of population-level analyses and suggest that species-wide conservation strategies may overlook critical regional declines.
Recommended Citation
Kariyawasam, M. (2026). Linking North American Demographic Trends to Mexican Non-Breeding Grounds in a Migratory Warbler [Master's thesis, The University of Texas Rio Grande Valley]. ScholarWorks @ UTRGV. https://scholarworks.utrgv.edu/etd/1964
Comments
Copyright 2026 Majuwana Gamage Dulanthi Dileka Kariyawasam. All Rights Reserved. https://proquest.com/docview/3371419587