Research on responses to military noise is funded by a grant from the Department of Defence.
Research on behavioral adjustments to anthropogenic noise was funded by a grant from the National Science Foundation (IOS-1256799) and Western Michigan University's Faculty Research and Creative Activities Award.
Much of our current research aims to how animals respond to environmental change. To address this general question, we focus on two animal groups that produce vocal signals - songbirds and frog. Male songbirds and frogs vocalize to attract potential mates, and male songbirds also sing to defend breeding territories. Our goal is to understand how males deal with evolutionarily novel features of their environments, including human-generated or anthropogenic noise, artificial lights, and built structures in their environment.
To address the effects of noise on signalling, we first start with describing the sound environment. We've advocated for better description and quantification of anthropogenic noise in wildlife studies, beginning with the relatively straightforward approach of using noise-calibrated microphones (Gill et al. 2015). We can then extract sound-pressure levels (SPL) directly from recordings, providing us with detailed records of SPLs over time and giving us the ability to time-match SPLs with singing and other behaviors. This allows us to understand if animals change how they signal in noise (several manuscripts in prep.), as well as to quantify spatial variation in sound environments (Job et al. 2016) and to identify drivers of variation in anthropogenic noise (Gill et al., in review).
We use experimental noise introductions to better understand these effects. We played noise to test whether male chipping sparrows change where they sing from based on noise levels and whether male frogs and songbirds rapidly adjust their calls in response to noise. And we're interested in linking song adjustments to reproductive success to understand whether the changes in song structure are costly or beneficial in noisy environments.
Increased levels of anthropogenic noise are not the only novel feature of human-altered environments that might affect signalling. Artificial light is important as well and two on-going undergraduate projects in our lab are exploring the relative effects of noise and light levels on timing of singing around dawn in house wrens and field sparrows.
In summer 2017, we'll be adding a new dimension to our work with a project exploring the effects of military noise on golden-winged and blue-winged warblers.