Electronic Theses and Dissertations

Date

2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biology

Committee Chair

James Adelman

Committee Member

Cassandra Nunez

Committee Member

Dana Hawley

Committee Member

David Freeman

Committee Member

Emerson Bowers

Abstract

Foraging is a fundamental behavior that animals use to acquire food resources. Because these resources are critical for survival and reproduction, animals are often thought to forage optimally, maximizing resource intake per unit of time. While the foraging behaviors of healthy animals often align with such predictions, we know little about how or if these predictions hold true in sick animals. This is especially relevant when considering sickness behaviors, or changes in behavior that accompany infection and frequently include lethargy and anorexia, both of which may alter foraging decisions or ability. Because food resources often cause animals to aggregate, a change in foraging behavior during infection could affect host-host contact rates and, therefore, pathogen transmission. The goals of this dissertation were to review how optimal foraging theory could be adjusted to account for changes with infection (Chapter 1), then empirically document how foraging behaviors change during a bacterial infection in a common songbird. Due to their widespread distribution and abundance, I used wild-caught house finches (Haemorhous mexicanus) and their pathogen, Mycoplasma gallisepticum (MG), as a model system. I first sought to determine how control and MG-infected house finches differ in their food preferences (Chapter 2). I then investigated whether the ease with which a food object can be consumed, known as handling time, could drive differences in foraging between healthy and sick birds (Chapter 3). Finally, I used computer vision techniques to determine if the foraging patterns I observed in a lab setting were also present in wild birds at backyard feeders (Chapter 4). The results in this dissertation suggest that 1) healthy birds make optimal foraging decisions in the lab and in the wild, 2) infection does indeed change the foraging behaviors of sick individuals, and 3) sick birds show a reduced preference for both higher quality and easier-to-consume food. Taken together, these results have implications for pathogen spread in wild animals that use shared food resources. Specifically, if healthy and sick animals make different foraging choices, differences in food quality across a patchy landscape could separate healthy and sick animals more than would be expected by chance.

Comments

Data is provided by the student

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Open Access

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