Date of Award


Degree Name

MS in Biological Sciences


Biological Sciences


College of Science and Mathematics


Clinton Francis

Advisor Department

Biological Sciences

Advisor College

College of Science and Mathematics


Sensory pollutants such as anthropogenic noise and night lighting now expose much of the world to evolutionarily novel sound and night lighting conditions, which can have detrimental effects on humans and wildlife. In my first chapter, we exposed wild Western Bluebird (Sialia mexicana) nestlings to noise, light, and combination (i.e., noise and light) treatments. Nests exposed to noise and light together experienced less predation than control and light-exposed nests, and noise-exposed nests experienced less predation than control nests, yet overall nest success was only higher in noise-exposed nests compared to light-exposed nests. Although exposure to light decreased nestling body condition and evidence was mixed for the singular effects of noise or light on nestling size, those exposed to noise and light together were smaller across several metrics than nestlings in control nests. Our results support previous research on the singular effects of either stimuli, including potential benefits, such as reduced nest predation with noise exposure. However, our results also suggest that noise and light together can negatively affect some aspects of reproduction more strongly than either sensory pollutant alone. This finding is especially important given that these stimuli tend to covary and are projected to increase dramatically in the next several decades. In my second chapter, we used a field-based manipulation to explore the role of audition in biodiversity perception and self-reported well-being of hikers. We used a “phantom chorus” consisting of hidden speakers playing bird vocalizations to experimentally increase audible birdsong biodiversity during “on” and “off” blocks on two hiking trails and surveyed hikers to record their self-reported perceptions of avian biodiversity and concepts reflective of attention restoration. We found that hikers exposed to the phantom chorus reported higher levels of restorative effects compared to those that experienced ambient conditions on both trails, although the causal relationships differed for each trail. Specifically, increased restorative effects were directly linked to the phantom chorus on one trail and indirectly linked to the phantom chorus on the other trail through perceptions of avian biodiversity. Our findings add to a growing body of evidence linking mental health improvements to nature experiences and, via our field-based manipulation, we identified audition as an important modality by which natural environments confer well-being. Finally, our results suggest that maintaining or improving natural soundscapes within protected areas may be an important component to maximizing human experiences, especially as tourism and noise pollution in protected areas grow.