Humans are extremely noisy and sounds that we produce are different in pitch and often much louder than sounds heard in most natural settings. Conservationists have worried that the new acoustic background dominated by human-generated noise may negatively affect many birds, namely because they rely heavily on vocal communication and noise may mask or drown-out their songs and calls, rendering them functionally silent. This may be especially problematic because acoustic characteristics of bird vocalizations are constrained by a species? evolutionary history and body size to specific frequency ranges and amplitude limits. In other words, species have acoustic niches and may unable to adjust vocalizations to effectively communicate in our noisy world. Recently, however, a few birds have been shown to have some flexibility in their acoustic niche and adjust their vocalizations to overcome the masking effects of noise. In this project, the investigators aim to 1) determine whether acoustic niche flexibility is common or rare within an avian community and 2) evaluate whether a species? ability to occupy noisy habitat is dependent on acoustic niche flexibility. To achieve these objectives the investigators will focus their research on ten species known to vary markedly in their tolerance to noise: four species that avoid noisy habitat, two species that prefer noisy habitat, and four species that appear uninfluenced by noise. For each species, the investigators will record and measure vocalization characteristics from many individuals singing or calling throughout a noisy intensity gradient. Because the project is a community-wide approach, results will enhance the limited understanding of the universality of acoustic niche flexible among bird species. This is especially important in terms of avian conservation in and around human-altered landscapes because it will provide needed insight as to why many species abandon noisy areas and why a handful may flourish.
