Term of Award

Fall 2025

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Isaac Park

Committee Member 1

Alan Harvey

Committee Member 2

Ray Chandler

Abstract

Many species across the globe have been observed to shift the seasonal timing of life history events in response to climate change-induced shifts in their local environments. However, individual species vary greatly in the direction and magnitude of these phenological shifts. Variation in phenological responsiveness to climate change among interacting species can lead to phenological asynchrony, with potential consequences for survival and population health. In years with increased spring temperatures, the timing of passerine chick rearing and of caterpillar activity may shift earlier or later in the year. Differences in the magnitude and/or direction of phenological shifts among passerines and caterpillars may lead to asynchrony, in which birds attempt to breed at a time of year when caterpillar food resources are not sufficiently abundant to allow successful rearing of chicks. Furthermore, certain life history traits may influence passerine species’ ability to shift their phenology and track changes in prey resource availability. To determine how climate change may be influencing phenology and risk of phenological asynchrony in passerine birds, this study aims to quantify 1) the rate at which passerine bird species shift the timing of chick rearing in response to increased temperatures, 2) the rate at which caterpillar species shift the timing of activity in response to increased temperatures, 3) how phenological responsiveness to increased temperatures differs between passerine chick rearing and caterpillar activity, and 4) how migratory status affects passerines’ phenological responsiveness to increased temperatures and subsequent risk of phenological asynchrony. Using long-term bird banding and encounter data in conjunction with citizen science records of caterpillar occurrences, it was determined that passerine birds and caterpillars are generally advancing the phenology of chick rearing and activity, but that passerines are advancing their phenology at a slower pace than caterpillars. It was also determined that non-migratory birds are better able to keep pace with shifts in caterpillar phenology than migratory birds. As caterpillars are a critical food resource for many nestling passerines, the potential for phenological mismatch between passerine chick rearing and caterpillar activity may lead to decreased chick survival and population declines, particularly for migratory passerines.

Research Data and Supplementary Material

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