The Role of Urbanization and Corticosterone in Auditory Sensory Processing in House Sparrows (<em>Passer domesticus</em>)

Urban habitat expansion will introduce new anthropogenic challenges for wildlife populations, including habitat fragmentation, novel predators, and pollution. These challenges may hinder animal communication and contribute to increased stress levels. This study will investigate the physiological consequences of stressors on the house sparrow (Passer domesticus). Specifically, we will examine how urbanization affects stress hormone (i.e., corticosterone, CORT) levels and its relationship to auditory processing. It is predicted that urbanization may impose novel stressors on animals, leading to differences in this hormone across urban and rural birds. We seek to understand if differences in CORT levels could impact animals' sensory processing abilities through experimental manipulation. To test this, we will manipulate CORT levels in house sparrows from urban and rural locations around Holland, MI, using mitotane, an injectable drug shown to reduce CORT levels effectively. Female and male birds will be collected from rural and urban locations surrounding Holland, MI. Blood samples will be taken and analyzed for baseline CORT. Auditory processing will be measured using auditory brainstem responses, which determines the ability of an individual to detect sounds at different frequencies and intensities. This research addresses a critical gap in understanding how CORT influences sensory physiological functions under urban stressors. We hypothesized that mitotane birds will have lower levels of chronic CORT levels than control birds due to mitotane lowering stress levels. Furthermore, we predict that mitotaneinjected birds will have higher sensory processing, while controls will have lower sensory processing due to higher levels of stress. The results will provide critical insights into the effects of urbanization on wildlife communication and physiology, informing conservation strategies in increasingly urbanized environments.