Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences

First Advisor

Doucet, Stephanie (Biological Sciences)


Biology, Ecology.



Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


Phenotypic variation arises through natural selection, sexual selection, and genetic drift. Large-scale variation is often demonstrated via clinal gradients, and small-scale variation is commonly exhibited by quality-indicating traits. My goal was to investigate geographic and individual phenotypic variation in golden-crowned kinglets, with particular focus on carotenoid-based ornaments. Through a museum study, I found that kinglet body size and coloration weakly followed well-established ecogeographic rules. However, sexual dichromatism was reduced in colder climates, providing support for a poorly recognized environmentally-induced cline. In a separate study, I captured migrating kinglets to determine how carotenoid content mediates inter- and intrasexual crown colour variation. I found that crown coloration was associated with migration timing, and females displayed additional condition-dependence of this trait. Overall, small-scale variation in crown coloration is dependent on pigment differences and individual quality, while large-scale variation is likely governed by differences in selection pressures.