Master of Science, The Ohio State University, 2012, Environment and Natural Resources
Animal communication systems, which rely upon complex cognitive behavior, specific social contexts, and environments that permit effective transmission, are vulnerable to disruption by anthropogenic disturbance. Forests in urban landscapes are known to differ from rural forests in terms of vegetation, avian communities, and anthropogenic noise. Although these urban-associated differences can elicit demographic consequences, little is known about sub-lethal behavioral effects. Recent studies have implicated anthropogenic noise as a cause of changing bird song in urban areas; however, few have considered alternative explanations, nor the evolutionary and ecological consequences of altered songs. I investigated song variation in an urban landscape by asking the following questions: 1) How do the structural and behavioral components of bird song change across a rural-urban landscape gradient? 2) Which aspects of urbanization best predict changes in song properties? and 3) Does urbanization alter relationships among song, indicators of fitness and male quality? I investigated these questions by recording vocal behavior and monitoring the breeding activity of individually-marked male Northern Cardinals (Cardinalis cardinalis) at nine sites distributed across riparian forests within a rural to urban landscape gradient in central Ohio.
Forests within urban versus rural landscapes differed ecologically so that urban forests had greater densities of conspecifics, denser understory vegetation with greater numbers of large trees, louder ambient noise (primarily from traffic), and smaller birds than more rural forests. As expected, cardinal song also changed with urbanization, with songs becoming longer, faster and with higher minimum, maximum and peak frequencies (Hz) as urbanization increased. Ambient noise at the territory level explained shifts in minimum frequency, whereas changes in conspecific densities best explained temporal variation in song structure (e.g., length an (open full item for complete abstract)
Committee: Amanda D. Rodewald PhD (Advisor); Douglas A. Nelson PhD (Committee Member); Mazeika S.P. Sullivan PhD (Committee Member)
Subjects: Ecology