JEA 2017, 1(1), 5; doi: 10.22261/jea.z9tqhu
Spatiotemporal patterns of avian vocal activity in relation to urban and rural background noise
1 Purdue University Department of Biological Sciences, Lilly Hall of Life Science, West Lafayette, IN, 47907, USA
2 George Mason University Biology Department, 4400 University Dr., Fairfax, VA, 22030, USA
* Author to whom correspondence should be addressed.
Received: 11 Aug 2017 / Accepted: 31 Oct 2017 / Published: 5 Dec 2017
Background noise can interfere with and influence acoustic communication behavior. Signal interference is dependent on the amplitude and spectral characteristic of background noise, which varies over space and time. The likelihood of signal interference is greater when background noise is concentrated within the same frequency bands of an animal’s vocalization, but even a partial masking effect can elicit signaling behavior modification. Relative to a rural landscape, background noise in an urban landscape is disproportionately comprised by anthro- pogenic sound, which fluctuates in amplitude throughout the day and occurs primarily in low frequencies (0–2 kHz). In this study, we examined if urban-rural differences in vocal activity patterns exist in a species Zonotrichia leucophrys nuttalli that communicates above the frequency range of anthropogenic noise (2–8 kHz). We tested whether vocal activity patterns changed in relation to sound in the high or low frequency bands within and between urban and rural locations. Automated acoustic recording devices (ARDs) continuously recorded throughout the morning song chorus, 0500 to 1,100 h, during the 2014 breeding season in San Francisco (urban) and Marin (rural) Counties, CA. Supervised learning cluster analysis was used to quantify vocal activity by totaling the number of songs. In general, vocal activity was greater in urban locations com- pared to rural locations. However, within rural and urban study sites, we found vocal activity decreased where low frequency noise levels were higher. There was not a relationship between vocal activity and high frequency, biotic sound. In both urban and rural locations, low frequency noise levels increased through the morning, while vocal activity remained relatively consistent. Our results demonstrate how patterns of vocal activity can change with low frequency, abiotic noise, even when there is no direct spectral overlap with the acoustic signal.
Keywords: urbanization; passive recording; vocal activity; bird song; anthropogenic noise; Nuttall’s white-crowned sparrow Zonotrichia leucophrys nuttalli
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Gentry, K.E.; Luther, D.A. Spatiotemporal patterns of avian vocal activity in relation to urban and rural background noise. JEA 2017, 1, 5.
Gentry KE, Luther DA. Spatiotemporal patterns of avian vocal activity in relation to urban and rural background noise. Journal of Ecoacoustics. 2017; 1(1):5.
Gentry, Katherine E.; Luther, David A. 2017. "Spatiotemporal patterns of avian vocal activity in relation to urban and rural background noise." JEA 1, no. 1: 5.