Date of Award

Spring 2006

Document Type

Restricted Thesis

Terms of Use

© 2006 Benjamin S. Ewen-Campen. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts



First Advisor

Julie Hagelin


In this study, we present the results of two consecutive years of breeding observations of the Arctic Warbler (Phylloscopus borealis kennicotti) in interior Alaska, which represent the most extensive collection of information on this species in North America. The aims of this study were two-fold. First, we described reproductive success across two habitat types. Second, we measured the insulation quality of nests during the second year of our study in order to test whether the substantial variation in nest mass and/or the use of moose hair was related to variation in insulation quality. We observed extremely high rates of nest success in both habitats (collectively 93% of nests fledged at least two chicks). However, we found nest density to be significantly lower and nest failure rate to be significantly higher on thickly vegetated plots that contained higher proportions of dwarf birch shrubs compared to more open plots dominated by willow shrubs. Both nest mass and moose hair mass varied significantly between habitat types, suggesting that Arctic Warblers are able to build nests from a variety of materials, possibly reflecting local availabilities. However, neither nest mass nor moose hair mass was related to insulation quality, reproductive success, or parental quality within either habitat. In addition, insulation quality was not related to any measure of reproductive success, length of nesting period, or parental size. This suggests that widely varying nest types built by Arctic Warblers are capable of providing sufficient insulation to developing chicks.