METHODS Background noise and bird song were recorded concurrently in the Fresno-Clovis Metropolitan...
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METHODS Background noise and bird song were recorded concurrently in the Fresno-Clovis Metropolitan Area (FCMA) and surrounding rural areas during February 2010-April 2011 using a: Marantz PMD670 digital recorder & Sennheiser K6 directional microphone Extech 407764 Sound Level Meter & Data Logger, sampling every 2 seconds in A-weighted amplitude measurements (dB). Song Components: For each bird sampled (26 WCSP, 38 HOFI), the clearest song was analyzed in Raven Pro 1.3 using Hann transformation at 1500 samples. We measured: SINGING THROUGH THE URBAN NOISE Song is a primary mode of communication in birds, both during the breeding and the non-breeding seasons. The sensory drive concept suggests that environmental conditions such as ambient sound influence the evolution of vocal behavior. Thus, background noise levels may have a profound effect on communication. Urbanization and associated vehicular traffic present the biggest modern source of noise, and thus a novel context in which to study the effects of noise on birdsongs. Here we examine how urban noise affects song structure in two species occurring in the rapidly urbanizing Central Valley of California: • the migratory White-crowned Sparrow (Zonotrichia leucophrys gambelii, WCSP): winters in the region, in urban and rural habitats. Song is an important territorial signal during non-breeding season. • the sedentary House Finch (Carpodacus mexicanus, HOFI): breeds in the region and occurs year-round in urban and rural habitats. Song is a mate- attraction and territorial signal in the breeding season. We hypothesize that birds that live in noisy/urban areas will sing at higher frequencies than birds that live in quiet/rural areas (Fig from Warren et al, 2006). ACKNOWLEDGMENTS We are grateful to Heather Hanlin, Patricia E. Sanders and Sonia Mendoza for their work on the project, the Division of Graduate Studies at CSU Fresno for financial support, and Elizabeth Derryberry for her helpful input. Photos: M. Katti REFERENCES Brackenbury, J. H. 1979. Power capabilities of the avian sound producing system. Journal of Experimental Biology 78:163-166. Brumm, H. 2004. The Impact of Environmental Noise on Song Amplitude in a Territorial Bird. Journal of Animal Ecology 73:434-440. Oberweger, K. and F. Goller. 2001. The metabolic cost of birdsong production. Journal of Experimental Biology 204:3379- 3388. Warren, P. S., M. Katti, M. Ermann, and A. Brazel. 2006. Urban bioacoustics: it's not just noise. Animal Behaviour 71:491-502. Effects of Urban Noise on Song Structure in a Sedentary and a Migratory Bird Species Jennifer N. Phillips, Pedro Garcia, Lauryn Moles, and Madhusudan Katti Department of Biology, California State University, Fresno [email protected] • [email protected] • [email protected] DISCUSSION Our results support the hypothesis that birds in noisy environments shift their frequencies upward, but the nature of this response is species specific. The significant upward shift of minimum frequency, and shrinking of bandwidth, in White-crowned sparrow song may be one of the first documented examples of a long distance migrant’s communication system being affected by urban noise in their wintering grounds. This may be a plastic behavioral response from White-crowned Sparrows to ambient noise at the time of recording, or could indicate population differentiation because all our quiet recordings were rural and noisy ones urban. The lack of change in maximum frequency in White-crowned Sparrow song could indicate physical constraints faced by the bird (Brackenbury, 1979 and Brumm, 2004) or metabolic costs (Oberweger and Goller, 2001). The House Finch shows a different pattern of response, with no apparent effect of background noise per se, but significant differences between urban and rural birds. Urban House Finches sing at significantly higher maximum frequencies even at low background noise levels, and slightly higher minimum frequencies, than their rural counterparts, resulting in a larger bandwidth. Rural House Finches show greater variability in maximum frequency and bandwidth at noisy than at quiet locations suggesting potential plastic behavioral response to noise. Urban House Finches also show high variability, and appear to sing at higher maximum frequencies at both noise levels. We suggest that these results indicate population-level song differentiation in House Finch song driven by persistent long-term noise in urban habitats. Urban noise thus has different effects on sedentary and migratory species. Future research will focus on: Analysis of fine temporal structure of songs in both species Two way analysis comparing the effects of Noisy/Quiet and Urban/Rural habitats. Playback experiments to document social and behavioral consequences of these changes in song. RECORDING LOCATIONS . . Maximum Frequency Bandwidth Minimum Frequency RESULTS White-crowned Sparrows sang at significantly higher minimum frequencies in noisy (>53dB background noise) compared to quiet (<51dB) areas (ANOVA, F 1,24 = 9.96 ; p = 0.004). Maximum frequency of White- crowned Sparrow song did not change with background noise levels. White-crowned Sparrow song in noisy areas had a significantly smaller bandwidth than in quiet areas (ANOVA, F 1,24 = 4.3 ; p = 0.049). House Finch songs did not differ between noisy and quiet areas for any of the three parameters measured. We then compared House Finch songs between Urban and Rural habitats within noisy and quiet locations. Among quiet locations, maximum frequency was significantly higher in urban than in rural songs (ANOVA, F 1,17 = 11.21 ; P = 0.004). Among quiet locations, bandwidth was significantly larger in urban than in rural songs (ANOVA, F 1,17 = 8.97; p = 0.008). Among noisy locations, there was no significant difference between urban and rural songs in any of the parameters, although minimum frequency was slightly higher in urban songs (ANOVA, F 1,17 = 11.21 ; p = 0.06). Habitat effects thus seem to override noise level effects in House Finch song. * * * *
Transcript of METHODS Background noise and bird song were recorded concurrently in the Fresno-Clovis Metropolitan...
METHODS
Background noise and bird song were recorded concurrently in the Fresno-Clovis Metropolitan Area (FCMA) and surrounding rural areas during February 2010-April 2011 using a: Marantz PMD670 digital recorder & Sennheiser K6 directional
microphone Extech 407764 Sound Level Meter & Data Logger, sampling every 2
seconds in A-weighted amplitude measurements (dB).
Song Components: For each bird sampled (26 WCSP, 38 HOFI), the clearest song was analyzed in Raven Pro 1.3 using Hann transformation at 1500 samples. We measured:
SINGING THROUGH THE URBAN NOISESong is a primary mode of communication in birds, both during the breeding and the non-breeding seasons. The sensory drive concept suggests that environmental conditions such as ambient sound influence the evolution of vocal behavior. Thus, background noise levels may have a profound effect on communication. Urbanization and associated vehicular traffic present the biggest modern source of noise, and thus a novel context in which to study the effects of noise on birdsongs.
Here we examine how urban noise affects song structure in two species occurring in the rapidly urbanizing Central Valley of California: • the migratory White-crowned Sparrow (Zonotrichia leucophrys gambelii, WCSP): winters in the region, in urban and rural habitats. Song is an important territorial signal during non-breeding season.• the sedentary House Finch (Carpodacus mexicanus, HOFI): breeds in the region and occurs year-round in urban and rural habitats. Song is a mate-attraction and territorial signal in the breeding season.We hypothesize that birds that live in noisy/urban areas will sing at higher frequencies than birds that live in quiet/rural areas (Fig from Warren et al, 2006).
ACKNOWLEDGMENTS
We are grateful to Heather Hanlin, Patricia E. Sanders and Sonia Mendoza for their work on the project, the Division of Graduate Studies at CSU Fresno for financial support, and Elizabeth Derryberry for her helpful input. Photos: M. Katti
REFERENCES
Brackenbury, J. H. 1979. Power capabilities of the avian sound producing system. Journal of Experimental Biology 78:163-166.
Brumm, H. 2004. The Impact of Environmental Noise on Song Amplitude in a Territorial Bird. Journal of Animal Ecology 73:434-440.
Oberweger, K. and F. Goller. 2001. The metabolic cost of birdsong production. Journal of Experimental Biology 204:3379-3388.
Warren, P. S., M. Katti, M. Ermann, and A. Brazel. 2006. Urban bioacoustics: it's not just noise. Animal Behaviour 71:491-502.
Effects of Urban Noise on Song Structure in a Sedentary and a Migratory Bird SpeciesJennifer N. Phillips, Pedro Garcia, Lauryn Moles, and Madhusudan Katti
Department of Biology, California State University, [email protected] • [email protected] • [email protected]
DISCUSSION
Our results support the hypothesis that birds in noisy environments shift their frequencies upward, but the nature of this response is species specific.The significant upward shift of minimum frequency, and shrinking of bandwidth, in White-crowned sparrow song may be one of the first documented examples of a long distance migrant’s communication system being affected by urban noise in their wintering grounds.This may be a plastic behavioral response from White-crowned Sparrows to ambient noise at the time of recording, or could indicate population differentiation because all our quiet recordings were rural and noisy ones urban.The lack of change in maximum frequency in White-crowned Sparrow song could indicate physical constraints faced by the bird (Brackenbury, 1979 and Brumm, 2004) or metabolic costs (Oberweger and Goller, 2001).
The House Finch shows a different pattern of response, with no apparent effect of background noise per se, but significant differences between urban and rural birds.Urban House Finches sing at significantly higher maximum frequencies even at low background noise levels, and slightly higher minimum frequencies, than their rural counterparts, resulting in a larger bandwidth.Rural House Finches show greater variability in maximum frequency and bandwidth at noisy than at quiet locations suggesting potential plastic behavioral response to noise. Urban House Finches also show high variability, and appear to sing at higher maximum frequencies at both noise levels.We suggest that these results indicate population-level song differentiation in House Finch song driven by persistent long-term noise in urban habitats.
Urban noise thus has different effects on sedentary and migratory species.
Future research will focus on: Analysis of fine temporal structure of songs in both species Two way analysis comparing the effects of Noisy/Quiet
and Urban/Rural habitats. Playback experiments to document social and behavioral
consequences of these changes in song.
RECORDING LOCATIONS
.
.
Maximum Frequency
Bandwidth
Minimum Frequency
RESULTSRESULTS
White-crowned Sparrows sang at significantly higher minimum frequencies in noisy (>53dB background noise) compared to quiet (<51dB) areas (ANOVA, F1,24 = 9.96 ; p = 0.004).
Maximum frequency of White-crowned Sparrow song did not change with background noise levels.
White-crowned Sparrow song in noisy areas had a significantly smaller bandwidth than in quiet areas (ANOVA, F1,24 = 4.3 ; p = 0.049).
House Finch songs did not differ between noisy and quiet areas for any of the three parameters measured.
We then compared House Finch songs between Urban and Rural habitats within noisy and quiet locations.
Among quiet locations, maximum frequency was significantly higher in urban than in rural songs (ANOVA, F1,17 = 11.21 ; P = 0.004).
Among quiet locations, bandwidth was significantly larger in urban than in rural songs (ANOVA, F1,17 = 8.97; p = 0.008).
Among noisy locations, there was no significant difference between urban and rural songs in any of the parameters, although minimum frequency was slightly higher in urban songs (ANOVA, F1,17 = 11.21 ; p = 0.06).
Habitat effects thus seem to override noise level effects in House Finch song.
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