Date of Award


Degree Name

MS in Biological Sciences


Biological Sciences


College of Agriculture, Food, and Environmental Sciences


Clinton Francis

Advisor Department

Biological Sciences

Advisor College

College of Agriculture, Food, and Environmental Sciences


Sensory environments are rapidly changing due to increased human activity in urban and non-urban areas alike. For instance, background sounds can interfere with parent-offspring communication and mask cues reflective of predation risk, resulting in elevated vigilance at the cost of provisioning. In chapter 1, we studied nestling provisioning behavior among Western Bluebirds (Sialia mexicana) in response to short-term (1 hr) and long-term (continuous exposure throughout nesting period) noise exposure. Provisioning rates were lower at nests exposed to short-term experimental traffic noise compared to exposure to ambient background sounds. Trial order strongly influenced provisioning behavior, with the decline in provisioning during noise playback occurring only during the second broadcast period of sounds. In contrast, provisioning rates increased with sound levels among nests exposed to long-term noise. Additionally, birds nesting in areas with high levels of noise returned to the nest more quickly than those in quiet areas following a simulated predation attempt. This study suggests that behavioral responses to short-term, experimental exposure to noise may not always be reflective of responses to longer-term noise exposure in real-world settings. It is essential to be cognizant of potential differences between experiments and real-world conditions as urbanization and sensory pollutants increase.

The pervasive spread of artificial light at night has been documented to disrupt natural rhythms with varying consequences on wildlife. Disruption to the night sky can alter nestling development either through indirect exposure to light or due to changes in adults’ behavior, both having potential physiological costs or benefits. In chapter 2, we experimentally manipulated light outside of Western Bluebird nesting cavities and investigated whether exposure to light at night affects nestling development and adult behavior. Our results found no evidence of light at night affecting the onset or cessation of adult daily activity. However, we found that nestlings exposed to light have smaller wing chords and lower mass, but better overall body condition than those in the control. The number of chicks in the nest also strongly influenced the effect of the light at night: nests exposed to light with brood sizes of three nestlings had smaller wing chords and better body condition than nests without lights, but there were no strong differences between light exposed and dark nests with five chicks. Although light exposure appears to improve chick body condition, the chicks were smaller overall. These findings suggest that indirect artificial light outside the nesting cavity is enough to have consequences on the development of nesting birds, and ecologically relevant light exposure appears to alter chick condition without a temporal shift in parental behavior.