Date of Award
Spring 4-14-2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Jacob C. Cooper
Committee Members
Keith Geluso
Letitia Reichart
Lucas DeCicco
Keywords
white-breasted nuthatch, Sitta carolinensis, contact zones, habitat preferences, vocalizations, secondary contact, Pine Ridge
Abstract
Populations’ interactions in contact zones are important for understanding divergence dynamics of closely related taxa. Such interactions may vary from inter-population divergence being reinforced to secondary contact resulting in the creation of a hybrid swarm. The ecology of each lineage, and different factors like behavior and ecological niches, may impact the outcome of such contact. However, there is little current research on how habitat choice at local scales might reflect distinct populations, particularly in cryptic species. To study how niche dynamics affect diversification, we studied the White-breasted Nuthatch (Sitta carolinensis) complex in northwestern Nebraska. Two members of this complex are undergoing secondary contact in this region, namely the interior Western S. c. nelsoni and Eastern S. c. carolinensis, with each taxon largely replacing the other across a purportedly narrow contact zone. Using vocal and morphological traits, we identified 96 nuthatches to population and used their locations to extract climate and habitat data. Climatic variables were found to have a negligible impact on limiting distributions, but Evergreen Forest cover proved to be significant. An additional 17 nuthatches were defined as ‘Intermediate,’ and four possible mixed pairs were found, potentially indicative of interbreeding. Moreover, one bird gave calls of both carolinensis and nelsoni. We also found that simple songs in White-breasted Nuthatches can be reliably differentiated by note shape, and that there are significant differences in pitch and rate of delivery between these songs. More work—particularly genetic analyses—is needed to understand the degree of intergradation in the region, as well as to understand the nature of vocalizations in this system.
Recommended Citation
Huryn, Eugene A., "SECONDARY CONTACT DYNAMICS IN WHITE-BREASTED NUTHATCHES (SITTA CAROLINENSIS) ACROSS THE PINE RIDGE OF NEBRASKA" (2026). Biology Theses, Dissertations, and Student Creative Activity. 22.
https://openspaces.unk.edu/bio-etd/22