@article {52600,
	title = {Spatiotemporal patterns of avian vocal activity in relation to urban and rural background noise},
	journal = {Journal of Ecoacoustics},
	volume = {1},
	year = {2017},
	month = {Apr-26-20172062},
	pages = {Z9TQHU},
	abstract = {<p>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\&rsquo;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 anthropogenic sound, which fluctuates in amplitude throughout the day and occurs primarily in low frequencies (0\&ndash;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\&ndash;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 compared 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.</p>
},
	doi = {10.22261/JEA10.22261},
	author = {Gentry, Katherine E.}
}
@article {52597,
	title = {Vocalizing during gaps in anthropogenic noise is an uncommon trait for enhancing communication in songbirds},
	journal = {Journal of Ecoacoustics},
	volume = {1},
	year = {2017},
	month = {Jul-06-20172238},
	pages = {TLP16D},
	abstract = {<p>Mounting evidence suggests that anthropogenic noise negatively impacts many wildlife species, including songbirds. One mechanism by which noise affects songbirds may be through acoustic obstruction to their systems of vocal communication. However, many species increase the amplitude or pitch of their vocalizations, which may partially mitigate the impact of high noise levels. When the amplitude of anthropogenic noise varies over time, such as near a moderate-use highway, short gaps between noise events may also provide an important opportunity for communication. But, whether songbirds adjust vocalization rates rapidly to avoid overlap with noise is unknown for most species. We used acoustic playback to expose songbirds to simulated road noise during the dawn chorus in otherwise quiet habitats. We measured vocalization rates under ambient conditions and during quiet gaps embedded within playback of road noise to assess whether a community of songbirds, and nineteen individual species, vocalize more regularly during noise gaps. There were no significant differences in community-wide acoustic output. Species-specific analysis revealed that only four species altered their vocal rates during quiet gaps in noise, but that the direction of the effect varied by species. Point count results revealed that birds generally remained on site for the duration of the experiment, suggesting that abandonment of noisy locations was unlikely to confound our results. In sum, increasing vocal output during short gaps in noise occurred in only a handful of species, perhaps contributing to the limited number of species that are found within noisy habitats.</p>
},
	doi = {10.22261/JEA10.22261/JEA.TLP16D},
	author = {Proppe, Darren S. and Finch, Emily}
}
