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The Impact of Ambient Noise on Eastern Bluebird (Sialia sialis) Nestling Begging
Perera, Sajithya Thapthinie
Perera, Sajithya Thapthinie
Abstract
A growing body of evidence suggests that environmental ambient noises, particularly anthropogenic noises from urbanization, impact animal acoustic systems. In this study, I tested whether eastern bluebird (Sialia sialis) nestlings adjust their begging calls to decrease the interference of ambient noise by recording chick begging along a disturbance gradient. Mean call feature measurements differed with age, with older birds calling more loudly but less frequently and for shorter durations. Call SNR, amplitude, rate, length, and frequency range measured 15 meters away from the nest were lower than measurements inside the nest box, indicating that the environment impacted the propagation of nestling vocalizations. Contrary to my prediction, eastern bluebird nestlings did not increase the amplitude of their begging calls nor did they vary other structural characteristics of vocalizations, even though signal to noise ratio (SNR) of nestling vocalizations decreased as ambient noise amplitude increased along the disturbance gradient. Interestingly, I found that prevalent weather conditions of temperature and humidity attenuated nestling begging calls. Specifically, in warmer more humid weather, while nestling call amplitude and rate as recorded inside the nest box increased, the begging calls attenuated outside the nest box. These results indicate that loud ambient noises likely mask chick begging calls, which suggests that chicks and parents may experience fitness consequences in noisy environments because of inaccurate or inefficient parent-offspring communication.
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Thesis is part of Honors ETD pilot project, 2008-2013. Migrated from Dspace in 2016.
Date
2008-05-27
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Keywords
Sialia sialis, Ambient noise, Eastern bluebird, Environmental noise, Traffic noise, Animal acoustics, Acoustic communication, Bluebird nestlings, Nestling begging
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Biology