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Two partially matching songs that share the same introductory trill
An example of soft song, comprised of high frequency warbled notes and lower frequency buzzes. Soft songs appear to contain song components that are rare in normal song types.
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Research Interests
I am broadly interested in behavioral ecology, sexual selection and bioacoustics. My dissertation research addresses the male-male function of bird song, and the reliability of song as an aggressive signal. Specifically, I am studying two singing behaviors, song matching and soft song, which have been hypothesized to function as aggressive signals in the song sparrow. I have focused on the use of song playback experiments to investigate receiver-dependent costs as a mechanism ensuring the reliability of song as a signal of aggressive intentions. In other studies, I am examining the acoustic characteristics of soft song, and the application of cardiac response measures to studyingt the perception of aggressive singing behaviors.
Overview
For my dissertation research I have planned five studies on singing behavior and aggressive signaling in the song sparrow:
(1) Partial song matching in an eastern population of song sparrows
In eastern populations of song sparrows, low levels of whole song sharing restrict opportunities for the kinds of complex matching interactions seen in western populations, where whole song sharing is high. Eastern males do, however, commonly share parts of songs. I hypothesized that eastern song sparrow males could perform song matching using partially-shared songs, i.e., songs that have one or more phrases in common. I have performed a playback experiment that 1) demonstrated partial song matching in a population of eastern song sparrows; and 2) provided evidence consistent with the hypothesis that matching is a signal of aggressive intentions.
(2) Response to partial song matching
I have performed a playback experiment to test the prediction that partially-matching songs elicit a stronger aggressive response from territorial male song sparrows than non-matching songs. This relationship is expected if the reliability of partial song matching is enforced by a receiver-dependent cost.
(3) Acoustic analysis of soft song
I am using acoustic analysis techniques to describe soft song in the song sparrow, and to make quantitative comparisons of acoustic features between soft song and normal song.
(4) Response to soft song
Soft song in song sparrows has recently been found to be the best predictor of an attack on a taxidermic mount (Searcy, Nowicki & Anderson unpubl.), providing evidence that soft song functions as a signal of aggressive intentions. I performed playbacks of soft song and normal song to individual males to test the hypothesis that receiver-dependent costs enforce the reliability of soft song. I predicted that soft song should elicit a stronger aggressive response from receivers compared to normal song.
(5) The cardiac response as a measure of song perception
I will examine the utility of the cardiac response (change in heart rate) to examine song perception by male song sparrows. I will monitor the heart rates of caged territorial males during playbacks of various acoustic stimuli to characterize cardiac responses, and to evaluate the effectiveness of cardiac measures for addressing song perception. Specifically, I am interested in using this measure to test the aversive effect of soft song.
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Publications
Anderson, R.C., Searcy, W.A. & Nowicki, S. Partial song matching in an eastern population of song sparrows Melospiza melodia. Animal Behaviour, Vol 69(1), 189-195. PDF.
Article in Science News Magazine.
Wolski, L.F., Anderson, R.C., Bowles, A.E. and Yochem, P.K. (2003). Measuring hearing in the harbor seal (Phoca vitulina): Comparison of behavioral and
auditory brainstem response techniques. Journal of the Acoustical Society of America: 113(1), 629-636. PDF.
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