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Behavioral Ecology and Sociobiology

, Volume 69, Issue 7, pp 1139–1151 | Cite as

Anthropogenic noise is associated with changes in acoustic but not visual signals in red-winged blackbirds

  • Alejandro A. Ríos-ChelénEmail author
  • Gavin C. Lee
  • Gail L. Patricelli
Original Paper

Abstract

Some birds in noisy areas produce songs with higher frequency and/or amplitude and altered timing compared to individuals in quiet areas. These changes may function to increase the efficacy of acoustic signals by reducing masking by noise. We collected audio recordings of red-winged blackbirds and measured noise levels. We found that males in noisier places produced songs with fewer syllables and slower repeat rate of elements in some components (rattles). Birds may also improve the efficacy of communication in noise by increasing usage of other signaling modalities. Red-winged blackbirds also perform a visual display in different intensities while singing. We also tested whether this species performs the visual display in different intensities according to current noise levels, and predicted that if the efficacy of songs is impaired in noisy places, males would compensate by performing a more intense visual display. For this, we also collected visual recordings from the same males from which we obtained acoustic recordings. We found no association between acoustic noise and the intensity of the visual display; thus, our results do not support the idea that males are using the visual display as a backup signal to communicate under acoustic noise. We discuss some possible explanations of this negative finding and for the observed noise-related changes in song length and rattle rate in the context of communication under noise.

Keywords

Chronic noise Anthropogenic noise Red-winged blackbird Multimodal signaling Birdsong Visual signal 

Notes

Acknowledgments

Ríos-Chelén was supported by a UC MEXUS-CONACYT fellowship. Support for the data collection was provided by UC MEXUS-CONACYT to AAR-CH, and by UC Davis and NSF grants (IOS-0925038 and IOS-1258217) to GLP. This project was approved by the U.C. Davis Institutional Animal Care and Use Committee (Protocol #16927). For advice and help in data collection and analysis, we thank Tom Hahn, Jessica Blickley, Alan Krakauer, Rene Beamonte, and members of the Patricelli Lab. We thank Mike Hall for allowing us to work in Conaway ranch, the Wetlands reserve, for allowing us to work in the Wetlands, and Jeff Stoddard for allowing us to work in the Yolo Bypass Wildlife Area. We are very thankful to Steve Funderburk who kindly read throughout the manuscript and detected typos and writing errors. We thank two anonymous reviewers who helped improving a previous version of this article. The authors declare that they have no conflict of interest.

Ethical standards

This study complies with the current laws of the country in which it was performed.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Alejandro A. Ríos-Chelén
    • 1
    • 2
    Email author
  • Gavin C. Lee
    • 1
  • Gail L. Patricelli
    • 1
  1. 1.Department of Evolution and EcologyUniversity of CaliforniaDavisUSA
  2. 2.Centro Tlaxcala de Biología de la ConductaUniversidad Autónoma de TlaxcalaTlaxcalaMéxico

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