Date Approved

2017

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Biology

Committee Member

Peter Bednekoff, PhD, Chair

Committee Member

Jamie Cornelius, PhD

Committee Member

Katherine Greenwald, PhD

Abstract

American Goldfinches (Spinus tristis) are partial migrants that overwinter in northern regions where winters can be extreme. To understand the role of urban development in facilitating use of a harsh climate, I conducted winter point count surveys (n = 297) at urban and rural sites across latitudes in Michigan. The following winter I trapped individuals in urban and rural settings to sample baseline and stress-induced plasma corticosterone (CORT) levels. Analyses revealed no interaction of latitude and urbanization in the winter distribution of American Goldfinches. Similarly, CORT concentrations did not differ between individuals trapped in urban and rural settings. It does not appear that American Goldfinches preferentially use urban areas in winter, and urban individuals do not exhibit different CORT responses to stressors. Birds captured at sites where feeders were regularly provided did display higher baseline CORT concentrations; birds with higher CORT may be more likely to locate supplemental food.

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Biology Commons

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