Undergraduate Honors Theses

Thesis Defended

Spring 2013

Document Type



Ecology and Evolutionary Biology

First Advisor

Dr. Michael Breed


The purpose of this study was to determine the relative importance of known sources of navigational information for invertebrates in Pogonomyrmex occidentalis ants. The seemingly simple question of how animals find their way home leads to the study of complicated interactions between sensory abilities of animals and their potential for solving problems. Complex animal behavior can be difficult to study and explain because scientists cannot make inferences about the thoughts or motives behind a given behavior, but only analyze concrete observations. To address this problem, simple animals can be used as model systems. Understanding what processes underlie common behaviors in small-brained creatures provides insight about the evolution of complex behavior. This type of “bottom up” study of navigation contributes to the overall understanding of spatial cognition and may help explain more complicated navigation behaviors such as map-reading and complex route memorization. This study analyzes the relative importance of polarized light patterns, landmarks, and panoramic cues on the ability of Pogonomyrmex ants to orient homeward during foraging. When an ant is displaced from its original location to a new spot around the nest, it initially walks in the direction its nest would have been, had the ant not been moved. However, when a wall was placed behind the nest while an ant was navigating homeward, it became disoriented, walked in random directions, and took more time to find its nest. This result suggests that the Pogonomyrmex rely on panoramic images of scenery, rather than the other tested navigation methods.