Measuring Noise-Induced Stress in Rural and Urban Songbirds

Abstract

With landscapes becoming increasingly urban worldwide, it is important for wildlife conservation efforts to monitor the effects that such urbanization has on wildlife and figure out why some individuals become urban adapters while others are displaced. Anthropogenic disturbances, such as traffic noise, can cause an increase in stress in vertebrates and could be the cause of displacement for many individuals. However, it is unclear if individuals accustomed to urban noise have a different physiological makeup compared to their rural counterparts. We examined baseline and stress-induced corticosterone levels in House Wrens, Troglodytes aedon, before and after an experimental noise treatment using a repeated measures design. We found that before treatment, the urban birds had higher baseline corticosterone levels in comparison to their rural conspecifics. Rural birds that had experimental traffic noise played to them significantly increased their baseline corticosterone levels as compared to rural birds in the control group. Urban birds in both the control and noise experimental groups had corticosterone levels that did not differ pre- and post-treatment. These results show that the stress response mechanisms between urban and rural House Wrens differ, possibly due to the urban birds habituating to the anthropogenic disturbances in their environment.