Meeting Abstract

P1.5  Friday, Jan. 4  How do black phoebe, Sayornis nigricans, songs differ along a gradient of noise pollution? SHEEDY, R.R.*; HOESE, W.J.; California State University Fullerton; California State University Fullerton rsheedy@fullerton.edu

Low-frequency, high-amplitude noise pollution overlaps with bird songs, interfering with songbirds’ ability to communicate effectively. Individuals in noisy areas often sing differently from conspecifics in quiet areas, presumably to avoid masking from noise pollution. Populations exposed to high noise levels increase time spent singing, increase song amplitude, increase song frequency, increase repetition, and change the time of day they sing compared to populations exposed to low noise levels. We examined a common sub-oscine songbird, the black phoebe (Sayornis nigricans), with an innate song, exposed to extreme noise levels in southern California. We hypothesized that black phoebes exposed to high noise levels would sing differently from populations exposed to lower noise levels. We measured background noise levels and recorded songs from 11 males at three study sites along a noise gradient. Minimum frequencies of black phoebe songs are positively correlated with noise pollution levels, to a point. Songs sung in quietest sites (<30 dBA) had average minimum frequencies of 2.877 kHz while individuals singing in background noise between 50-60 dBA averaged 3.312 kHz. Songs sung in noisiest sites (>70 dBA) had average minimum frequencies of 3.272 kHz. Similarly, in previous research, a sub-oscine, the ash-throated flycatcher (Myiarchus cinerascens), showed they increased song minimum frequency up to a threshold of 70 dBA, above which minimum frequencies no longer increased. Increasing minimum frequencies reduces song bandwidth. Costs of changing songs beyond a certain point may outweigh the benefits of reduced masking. Investigating how urban adapted species cope with noise helps us understand how species can persist with expanding urban development.