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Academic Programs and Concentrations
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Research done in migratory birds over the last few decades has provided strong evidence suggesting that birds use cues from polarized light in the sky to guide orientation and navigation. If birds are able to detect skylight polarization patterns, then they could also be sensitive to polarized light in other non-migratory contexts – a possibility that has received minimal attention in the literature. Aquatic insects are known to depend on polarized light to identify water. While, historically, this has been a reliable cue, the rise and spread of urbanization has resulted in an increase in anthropogenic sources of polarized light – such as black asphalt roads and glass windows. Aquatic insects have been shown to misidentify anthropogenic sources of polarized light as water and exhibit maladaptive behaviors like oviposition at these objects. Although it has not yet been proven, there is some anecdotal evidence suggesting that birds may also use polarized light to identify water. This use of polarized light cues could put birds in danger of misinterpreting anthropogenic polarizers, which could cause them to partake in maladaptive behaviors at anthropogenic sources of polarized light. In this study, I develop two multiple-choice experiments that expose birds to horizontal surfaces that vary in degree of polarization. I show that three songbird species are preferentially attracted to the most polarizing surface. These data strongly suggest that birds are sensitive and attracted to polarized light in a non-migratory context and provide preliminary evidence suggesting that birds may use polarized light to detect water. These results further suggest that, like insects, birds may be in danger of misinterpreting polarized light reflected from anthropogenic sources, meaning that anthropogenic polarizers could be having a larger impact on natural ecosystems than previously thought.
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Easthausen, Imaani J., "Songbirds and Their Sunglasses: A Study Demonstrating Avian Attraction to Highly Polarizing Horizontal Surfaces" (2015). Senior Projects Spring 2015. 138.
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