Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences



First Advisor

Dr. David F. Westneat


My dissertation investigates how animals behaviorally respond to environmental change, especially when there is limited information about that change. Uncertainty about the environment comes in various forms, including food resources which vary unpredictably and novel cues which present an unknown level of potential risk or benefit. Various behavioral strategies help animals cope with such uncertainty. Tactics to manage unpredictable variation in food include gathering information to reduce uncertainty (sampling) and strategically adjusting preference or aversion to variation in resources (variance-sensitivity). To manage the uncertainty of a novel cue, animals may generalize their previous experience with similar cues, or they may minimize the potential risk of the novel cue by reacting to it with aversion (neophobia). Because of the costs associated with the latter (increased stress or lost opportunities), animals lose their aversion to an initially novel cue with repeated exposure (habituation). While much research focuses on how animals in general should optimally employ these strategies, there is also evidence that individuals vary consistently in how they manage uncertainty. To open my dissertation, I review several ways in which foraging theory focused on optimal behavior may be enriched by incorporating individual differences in uncertainty-management. Moving forward, I use house sparrows as a model organism to empirically investigate how and why individuals differ in various uncertainty-management behaviors.

First, I focus on strategies for dealing with novel cues. I show that sparrows are neophobic on average and their neophobic response declines (i.e., they habituate) across a series of exposures to similar novel objects, implying that they generalize among them. Moreover, individual sparrows differ significantly in both their neophobia and the rate at which it declines, implying individual differences in generalization. Next, I explore whether sparrows’ propensity to generalize is affected by the perceived threat of the cues being compared (adjusted by using objects with vs. without eyespots), or by the axis along which they differ (objects differing in color vs. size). Despite theoretical predictions to the contrary, I find no significant evidence that these factors affect generalization, though eyespots do affect neophobia. Finally, I explore whether differences in glucocorticoid hormone levels may underlie individual differences in neophobic behavior. To do this, I use dietary supplementation to temporarily elevate sparrows’ corticosterone and measure the effect on neophobia. I find no significant effects of short-term corticosterone elevation on behavior.

Lastly, I shift focus to strategies for managing unpredictable variation in food. Specifically, I investigate whether individual sparrows differ in their sampling and variance-sensitive behavior, and whether they adjust these behaviors in response to dietary restriction. On average, sparrows engage in more sampling under dietary restriction, but their variance preferences are not affected. There is also significant among-individual variation in both sampling and variance preferences, but not in how these behaviors are altered by dietary restriction. In conclusion, strategies for managing uncertainty exhibit complex variation both among and within individuals, and both the proximate and ultimate causes of this variation remain fertile ground for further research. Such work facilitates a deeper and more nuanced understanding of the eco-evolutionary forces that shape natural populations.

Digital Object Identifier (DOI)

Funding Information

National Science Foundation: IOS1257718, funding provided to D.F. Westneat in 2013, went towards infrastructure that was used by the author throughout the dissertation process (2015-2023).

University of Kentucky: Research Ribble Award (2015), Ribble Mini-Grant (2019), Graduate School Academic Year Fellowships (2017 & 2021).

Available for download on Monday, April 01, 2024