Grant: Research Tools and Instruments

Animals vocalize with impressive variety and while the variation in vocal behaviour among species is easy to recognize, there is also considerable within species variation, some of which we can recognize by ear, but a considerable amount we can also detect using acoustic recording techniques. This means that listeners, like mates and rivals can extract information about the quality of others from listening to vocalizations of others, which can have implications for their reproduction and survival. Songbirds are an excellent system in which to study this variation because bird sing prolifically both to attract mates and to defend their territory boundaries. The function of birdsong as an indicator of individual quality hinges on the repeatability of vocal behaviours (i.e. across time an individual sends the same information about their ability to defend a territory or as a good quality mate). However, whether consistent among-individual differences in many vocal behaviours exist is not well known. Estimating the repeatability of a suite of vocal traits (e.g. amount of singing, timing of singing, characteristics of song structure) is required to determine which components are important. I seek funding for the purchase of 30 autonomous recorders, which are a proven technique for studying individual, population, and communities of songbirds. My students and I will use this equipment to record white-throated sparrows and ovenbirds across entire breeding seasons. We will measure song traits and relate them to measures of individual quality, to social factors and to the environment. This will allow us to explore the interplay between plasticity (variation in response to changing conditions) and repeatability of vocal signals. Understanding repeatability is also important because human activity (e.g., climate change, habitat fragmentation, noise and light pollution) is increasingly affecting natural populations. Anthropogenic disturbance of singing behaviour and/or its reliability may affect species in complex ways that we have not yet fully modelled. Using song traits that are found to be repeatable, we will then use the requested autonomous recorders to explore how these traits may vary in a changing environment. In white-throated sparrows we will explore how urban cover and anthropogenic noise affect repeatability of signals while in ovenbirds, we will explore how forestry practices influence repeatability of signals. If signals are less reliable in the face of anthropogenic disturbance, this may mean that mates and rivals make incorrect decisions when using song to assess others. By identifying which signalling strategies are stable and which vary across these gradients, we will advance our understanding of how anthropogenic disturbance may influence advertising signals and their reliability, which has implications for populations of species that may be declining despite available habitat.