When to change your tune? Unpaired and paired male house wrens respond differently to anthropogenic noise
1 Department of Biological Sciences, Western Michigan University, 1903 West Michigan Ave., Kalamazoo, MI 49008-5200, USA
2 Ecology Program, The Pennsylvania State University, 221 Forest Resources Building, University Park, State College, PA 16802, USA
3 Department of Biological Sciences, Institute of the Environment and Sustainability, Western Michigan University, Kalamazoo, MI, USA
* Author to whom correspondence should be addressed.
Received: 30 Mar 2018 / Accepted: 16 Jul 2018 / Published: 3 Sep 2018
Abstract
In response to anthropogenic noise, many bird species adjust their song frequency, presumably to optimize song transmission and overcome noise masking. But the costs of song adjustments may outweigh the benefits during different stages of breeding, depending on the locations of potential receivers. Selection might favor unpaired males to alter their songs because they sing to attract females that may be widely dispersed, whereas paired males might not if mates and neighbors are primary receivers of their song. We hypothesized male house wrens (Troglodytes aedon) respond differently to noise depending on their pairing status. To test our hypothesis we synthesized pink noise, which mimics anthropogenic noise, and played it at three intensities in territories of paired and unpaired focal males. We recorded their songs and analyzed whether song structure varied with pairing status and noise treatment. To validate our study design, we tested whether noise playback affected measurement of spectral song traits and changed noise levels within territories of focal males. Consistent with our predictions, unpaired males sang differently than paired males, giving longer songs at higher rates. Contrary to predictions, paired males changed their songs by increasing peak frequency during high intensity noise playback, whereas unpaired males did not. If adjusting song frequency in noise is beneficial for long-distance communication we would have expected unpaired males to change their songs in response to noise. By adjusting song frequency, paired males reduce masking and produce a song that is easier to hear. However, if females prefer low frequency song, then unpaired males may be constrained by female preference. Alternatively, if noise adjustments are learned and vary with experience or quality, unpaired males in our study population may be younger, less experienced, or lower quality males.
Keywords: bird song; anthropogenic noise; signal design rules; house wren; pairing status; playback experiment
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CITE
Grabarczyk, E.E.; Pipkin, M.A.; Vonhof, M.J.; Gill, S.A. When to change your tune? Unpaired and paired male house wrens respond differently to anthropogenic noise. JEA 2018, 2, 13.
Grabarczyk EE, Pipkin MA, Vonhof MJ, Gill SA. When to change your tune? Unpaired and paired male house wrens respond differently to anthropogenic noise. Journal of Ecoacoustics. 2018; 2(2):13.
Grabarczyk, Erin E.; Pipkin, Monique A.; Vonhof, Maarten J.; Gill, Sharon A. 2018. "When to change your tune? Unpaired and paired male house wrens respond differently to anthropogenic noise." JEA 2, no. 2: 13.
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