Anthropogenic noise is increasingly widespread as human development continues. Noise can negatively affect humans and wildlife, but the most deleterious effects are incurred by species that rely on vocal communication for mating, territory defence, and other vital functions. Songbirds are particularly susceptible, often experiencing declines in richness and abundance in noise-affected areas. Yet, some species remain abundant in noisy environments. High frequency vocalizations, or the ability to shift to higher frequencies, is one adaptation that may allow birds to communicate above low frequency anthropogenic noise. However, the mechanisms underlying frequency shifting,
and the relationship between vocal frequency and abundance, are still not fully understood. I examined whether black-capped chickadees produce songs at higher frequencies in noisy areas, and whether these differences could be due to altered vegetative structure rather than noise. I also examined whether chickadees could plastically change song frequencies as noise increased. Finally, I surveyed abundance and recorded vocalizations from several songbird species to evaluate whether plasticity in song frequency, or mean song frequency, could predict how abundance and urban prevalence would be affected by anthropogenic noise. I
found that black-capped chickadees shifted to higher song frequencies in noise-affected areas, and that vegetative differences did not account for these changes. Further, chickadees at roadside locations plastically increased their song frequencies as noise levels increased. Vocal plasticity, however, was not related to abundance in my multi-species comparison. Instead, noise-related changes in abundance were predicted by a species minimum song frequency. Nevertheless, minimum song frequency did not necessarily predict whether a species would be widespread in urban areas. In addition to frequency parameters, urban species may avoid overlap with noise through spatial and temporal mechanisms, but those that lack any mechanisms to communicate within anthropogenic noise may experience declines. Thus, reducing anthropogenic noise may increase the quality of urban habitats for birds. / Ecology
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/1578 |
| Date | 11 1900 |
| Creators | Proppe, Darren |
| Contributors | St. Clair, Colleen Cassady (Biological Sciences), Sturdy, Christopher (Psychology), Bayne, Erin (Biological Sciences), Palmer, A. Richard (Biological Sciences), Slabbekoorn, Hans (Biology) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 789010 bytes, application/pdf |
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