Date of Award

2025

Document Type

Honors Thesis (Open Access)

Department

Colby College. Biology Dept.

Advisor(s)

Catherine Bevier

Second Advisor

Chris Moore

Third Advisor

Philip Nyhus

Abstract

Ecologists developed optimal foraging theory as a framework to understand how an animal may spend minimal time to maximize resource intake. A giving-up density (GUD) is a metric of the density of remaining food in a food patch at which an animal decides foraging is no longer economical. This study aims to test how the intensity of direct and indirect predator cues alter foraging patterns of deer mice. To measure GUD, I used depletable food patches deployed in the “upper woods” on the periphery of Colby College. To simulate direct predator cues, 1 mL of fox urine was applied on four cotton balls at different time lags (0, 1, and 4 hours) and deployed at experimental food patches. Mice foraged in the food patches through each trial night until sunrise, when the remaining seeds were collected and weighed in the lab. I found that Peromyscus spp. use indirect cues more than direct cues when evaluating predation risk. There was no significant change exhibited within all urine intensity levels, but forager tolerance for risk reduced in the presence of fresh urine. I saw a significant relationship between weather and GUD, as there was a 13% reduction in mean proportional GUD in rainy compared to clear weather. Seasonal differences also emerged, as 68% of summer trials exhibited complete seed removal from natural low food availability. These findings highlight the importance of indirect cues in shaping foraging strategies and contribute to a nuanced understanding of the landscape of fear.

Keywords

Behavioral Ecology, Giving-up Density, Optimal Foraging Theory, Peromyscus, Predator Cues, Landscape of Fear

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