Graduation Year

2026

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Organismal Biology

Reader 1

Sarah Budischak

Reader 2

Elise Ferree

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Terms of Use for work posted in Scholarship@Claremont.

Abstract

In an attempt to continue to improve conservation tactics, seasonal changes in how a habitat is used should be considered to ensure a conserved habitat serves its populations all year round. An ideal conservation site will be able to meet the changing habitat use of populations in all seasons. One way to conceptualize differing habitat use is in the local density of a population. As seasons change, if these local densities change then it is likely that individuals are using their habitat differently and either spreading out from other members of the population or associating closer. This local density can also have impacts on physiological aspects of individuals, importantly stress. High stress levels can lead to immunosuppression and leave individuals more vulnerable to health issues like parasitic infections. This dynamic between season, local density, stress, and infection rates could help provide further insight on habitat use and conservation success. I predicted that higher local densities would correspond to higher stress levels and infection rates, particularly in mating seasons. Based on data gathered using the California Towhee as a model inside the conserved sage brush habitat of the Robert J. Bernard Biological Field Station, I determined that Towhee local densities were lower in summer when they breed but the relationship between stress and density as well as parasites during different seasons was more complex. During summer the range of local density was very low, but stress and local density were inversely related. There was no overall significant difference in seasonal stress or local density related to parasitic infection but among just infected individuals, but summer Towhees were more stressed than in fall or spring. Overall, there was significantly different habitat use in summer that impacts Towhee health which should be considered when planning conservation efforts.

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