Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology & Evolutionary Biology

First Advisor

Alexander Cruz

Second Advisor

Robert P. Guralnick

Third Advisor

Clinton D. Francis

Fourth Advisor

Chris A. Lowry

Fifth Advisor

Rebecca J. Safran

Abstract

The presence of human caused noise is now virtually inescapable, making characterization of its impact on wildlife critical. I examined the effects of noise from natural gas extraction on a community of birds in a piñon-juniper woodland, using a large-scale field system. Noise can impact behaviors related to territory defense, and with a song playback experiment, I found that birds in loud areas have subdued responses to conspecific territory intruders. Developing and installing a system of 240 nest boxes throughout a gradient of noise uncovered that two species, the ash-throated flycatcher (Myiarchus cinerascens), and mountain bluebird (Sialia currucoides), display a negative occupancy response with increased noise levels. Western bluebird, Sialia mexicana, displayed noise tolerance. Importantly, the negative occupancy trends with noise were as strong or stronger than the effect of canopy cover percentage, a known factor driving habitat use in these species. Finally, I look at how relationships between hatching success, nestling development and stress hormones could be driven by noise exposure. I find that baseline stress hormones are lower for birds nesting in noisy habitats. Based on research from psychology this trend of ‘hypocorticism’, suggests that noise acts as a chronic psychological stressor in birds. Importantly, noise also has negative effects on nestling development and hatching success, which suggests that low levels of stress hormones could also indicate low quality habitats. In summary, my dissertation provides strong evidence that anthropogenic noise drives negative population consequences in birds and informs ecological theory, conservation and management

Available for download on Saturday, October 10, 2020

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