Available at: https://digitalcommons.calpoly.edu/theses/1829
Date of Award
MS in Biological Sciences
Throughout the world, birds represent the primary type of wildlife that people experience on a daily basis. However, a growing body of evidence suggests that alterations to the acoustic environment can negatively affect birds as well as humans in a variety of ways, and altered acoustics from noise pollution has the potential to influence human interactions with wild birds. In this thesis, I investigated how anthropogenic noise impacts daily behavior as well as community structure of wild birds. In the first component of this thesis, I assessed the distance at which a bird initiates flight or escape behavior (i.e., flight initiation distance or FID) in varying acoustic conditions. I surveyed 12 songbird species from three foraging guilds, ground foragers, canopy gleaners, and hawking flycatchers, and I predicted FIDs to decrease, remain the same, and increase with noise exposure, respectively. Contrary to expectations, the canopy gleaning and flycatching guilds exhibited mixed responses, with some species exhibiting unchanged FIDs with noise while others exhibited increased FIDs with noise. However, FIDs of all ground foraging species and one canopy gleaner decreased with noise levels. In the second component, I examined the feeding of wild birds, an increasingly popular recreational activity throughout North America that promotes increased sense of wellbeing by connecting people with wildlife and nature. I tested how experimental noise influences abundance, species richness, community structure and foraging behavior of songbirds at maintained bird feeders. By measuring activity levels of all species that utilized the feeders exposed to intervals of quiet and noisy conditions, I found noise to be a significant predictor of community turnover. Specifically, noise exposure resulted in increased feeder activity for two species, and decreased activity for one species. I also confirmed previous research conducted in the laboratory indicating white-crowned sparrows decrease their foraging rate under noise conditions, presumably as a trade off with visual vigilance. Considering the interactions of humans and wild birds, the results from my two thesis components indicate that the acoustic environment can play a role in how species of different foraging guilds respond to birdwatchers and what species visit bird feeders.
Outstanding Thesis 2017-2018